Researcher basic information

• 博士（地球環境科学）, 北海道大学

• https://researchmap.jp/5-3?lang=en

• https://orcid.org/0000-0003-4628-1074
• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201801015281292205
• https://uaf-iarc.org/?directory_entry=go-iwahana

• 70431327

• https://orcid.org/0000-0003-4628-1074

• 201801015281292205

• Permafrost
• Geocryology
• Ground ice
• Frozen ground
• Reconstruction of paleo-environment
• Remote sensing
• Forest fire
• Wildfire
• Micrometeorology
• Cold region engineering
• Tundra

• Natural Science, Human geosciences
• Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention), Geotechnical engineering
• Life Science, Forest science
• Humanities & Social Sciences, Geography
• Natural Science, Atmospheric and hydrospheric sciences
• Environmental Science/Agriculture Science, Environmental impact assessment
• Environmental Science/Agriculture Science, Environmental dynamic analysis

Research activity information

• Geochemical Characterization of East Siberian Ice Wedges: Implications for Paleoenvironmental Conditions and Provenance
  Subon Ko; Younghoon Won; Eunji Byun; Sungsik Lee; Wook‐Hyun Nahm; Go Iwahana; Nicolai Fedorov; Jinho Ahn; Alexander Fedorov; Giehyeon Lee
  Permafrost and Periglacial Processes, Apr. 2026
  Scientific journal
• Mechanism of Ice‐Wedge Formation and Mixed Origin of Trapped Greenhouse Gases in Zyryanka Permafrost, Northeastern Siberia
  Nayeon Ko; Hansu Park; JeongEun Kim; Nikolai Fedorov; Go Iwahana; Alexander Fedorov; Hyejung Jung; Jeonghoon Lee; Hotaek Park; Kimpei Ichiyanagi; Eunji Byun; Jinho Ahn
  Permafrost and Periglacial Processes, Jan. 2026, [Peer-reviewed]
  English, Scientific journal
• East Siberian ice wedges recording dust transport variability during the Late Pleistocene
  Soyeon Kim; Hyunwoo Lee; Jeongmin Kim; Yuyoung Lee; Jeong-Heon Choi; Mi Jung Lee; Ui-Jin Kwon; Go Iwahana; Thomas Opel; Hanno Meyer; Sebastian Wetterich; Alexander Fedorov; Jinho Ahn
  Nature Communications, 10 Nov. 2025, [Peer-reviewed]
  Scientific journal
• Integrated analysis of socio-ecological impacts on underground food storage in Beringia
  Kazuyuki Saito; Yu Hirasawa; Michael S Koskey; Yoko Kugo; Theresa John; Go Iwahana; Shirow Tatsuzawa
  Environmental Research: Ecology, 4, 2, 025007, 025007, IOP Publishing, 22 May 2025, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Underground storage utilizing natural cold energy, a long tradition of communities in Beringia closely integrated within their lifeways, is challenged by malfunctions or difficulties in appropriate use, affecting food security and food sovereignty, and community wellbeing. Previous studies tend to center on physical aspects in individual ice cellar cases in permafrost zones. In this study, we investigated impacts of climate and socio-ecological changes on underground food storage through analysis of local community interviews and proactive dialogues between local community experts and scientists to illustrate (1) the roles of cold storage in supporting their sustainable foods and lifestyles, (2) the causes and factors related to the issue of dysfunction of and/or decrease in underground cold storage use and eventual decline in use, and (3) consequent losses and damages these changes brought. Thereby, we enhanced and applied a ‘Food Life History’ framework, a working hypothesis constructed to address human-environment issues in a holistic, multiperspectival, and integrated way. The results show that changes in underground cold storage practices are not caused by a single factor (e.g. climate change or permafrost degradation alone), but through a variety of agents that have influence on different time scales (e.g. colonization, globalization, food changes, technologies for subsistence). Included is a relational diagram depicting the interrelations of relevant factors impacting the role and functionality of underground cold storage practices of a tradition more than a century old. It will serve to provide suggestions for sharing ideas and intuitive understandings of current situations, and a template to address and examine key points and potential policy options for future planning with respect to the resilience and wellbeing of communities, fostering open and transparent discussion., 49772114
• InSAR estimates of excess ground ice concentrations near the permafrost table
  S. Zwieback; G. Iwahana; Q. Chang; F. Meyer
  ISPRS Journal of Photogrammetry and Remote Sensing, 223, 261, 273, Elsevier BV, May 2025, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Spatiotemporally continuous temperature monitoring using optical fibers ( Loop 2 ) for ground surface and subsurface with various vegetations on a flat area with slope surface in the internal Alaska from 2016 to 2019
  Inoue, Tadao; Saito, Kazuyuki; Iwahana, Go; Ikawa, Hiroki; Nagano, Hirohiko
  Polar Data Journal, 9, April, 14, 29, Apr. 2025, [Peer-reviewed]
  English, Scientific journal
• Understanding water flowpaths and origins in an Arctic Alaskan basin: Implications for permafrost hydrology under global warming
  Hyejung Jung; Jinho Ahn; Go Iwahana; Jeonghoon Lee
  Advances in Climate Change Research, 16, 2, 361, 372, Elsevier BV, Apr. 2025, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Permafrost hydrology in an Arctic tundra ecosystem: quantifying water sources using stable water isotopes
  Hyejung Jung; Jinho Ahn; Go Iwahana; Jeonghoon Lee
  Copernicus GmbH, 20 Jan. 2025
  Global warming in the Arctic can lead to the alteration of the hydrological cycle and the thawing of permafrost. In this study, we utilized stable water isotope techniques (δ2H and δ18O) to infer the sources mixing of stream water at two sites (HV and PS) along the Sag River on the North Slope, Alaska (USA) during August 2022. The isotopes of snow and rain samples were plotted above the LMWL and reflected the isotopic characteristics of seasonal precipitation in Alaska. The porewater collected within the active layer showed enriched isotope values than other samples, indicating summer precipitation. Using δ18O and deuterium excess in a Bayesian mixing model, we estimated the contribution rates of summer precipitation, seasonal ice, and ice wedge. The results indicated a substantial contribution from melted seasonal ice (HV: 96.8% and PS: 74.1%), formed by frozen precipitation from the previous year, to surface water in August. Additionally, it was observed that the contribution of ice wedge was relatively greater in the downstream (PS: 21.8%) compared to the upstream (HV: 2.1%). Furthermore, we observed that the isotopic compositions of surface water in the PS site revealed evidence of evaporation, as indicated by a characteristic isotopic fractionation slope. Summer precipitation (HV: 1.1% and PS:4.1%) did not contribute substantially to surface waters. This research provides insight into fundamental processes related to sources and mixing of waters in permafrost hydrology.
• High‐Resolution Morphometric Analysis of Patterned Grounds in the Daisetsu Mountains, Hokkaido, Northern Japan
  Mamoru Ishikawa; Hiro Kamiya; Go Iwahana
  Permafrost and Periglacial Processes, 36, 2, 259, 271, Wiley, 20 Jan. 2025, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, ABSTRACT
  
  We evaluated the morphology, geomorphic settings, and micrometeorological controls of sorted polygons, stripes, lobate patterns, and turf‐banked terraces in two summit areas of Daisetsu Mountain, Japan, using orthophoto images and digital surface models generated from unmanned aerial vehicle observations and structure‐from‐motion techniques and in situ records of air temperature, wind speed/direction and ground temperatures. The sorted polygons on flat terrain are equiform and large (3.5 m in mean length), but on gentle slopes, they are elliptical and small (2.9 m). Sorted stripes and lobate patterns occur on slope steeper than 3.5°–4.5°. The form transition of sorted patterned grounds is considered due to activities of frost heave and thaw settlement, gelifluction, and frost creep, as well as the spatial pattern of soil wetness. In the windward slopes steeper than 3.5°–4.5°, the ground materials move downslope, forming lobate patterns and sorted stripes. On the flat surfaces and leeward slopes, snow accumulation prevents soils from cooling in winter, provides snowmelts to the soils, and thus thickens the seasonal thawing during summer, allowing sorting at greater depths and enlarging the diameters of the frost patterned forms. Snow redistribution and snowmelt infiltration produce locally moist soils, creating favorable environments for plant growth on leeward, that is, eastward sides of microtopography. Soil movements along slopes are dammed on the slope covered with dense vegetation cover where risers of turf‐banked terrace are formed. This is the explanation why the turf‐banked terraces are typically facing slightly eastward from principal slope direction.
• Thawing permafrost is subsiding in the Northern Hemisphere—review and perspectives
  Dmitry A Streletskiy; Alexey Maslakov; Guido Grosse; Nikolay I Shiklomanov; Louise Farquharson; Simon Zwieback; Go Iwahana; Annett Bartsch; Lin Liu; Tazio Strozzi; Hanna Lee; Matvey V Debolskiy
  Environmental Research Letters, 20, 1, 013006, 013006, IOP Publishing, 01 Jan. 2025, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  High-latitude and altitude cold regions are affected by climate warming and permafrost degradation. One of the major concerns associated with degrading permafrost is thaw subsidence (TS) due to melting of excess ground ice and associated thaw consolidation. Field observations, remote sensing, and numerical modeling are used to measure and estimate the extent and rates of TS across broad spatial and temporal scales. Our new data synthesis effort from diverse permafrost regions of North America and Eurasia, confirms widespread TS across the panarctic permafrost domain with rates of up to 2 cm yr⁻¹ in the areas with low ice content and more than 3 cm yr⁻¹ in regions with ice-rich permafrost. Areas with human activities or areas affected by wildfires exhibited higher subsidence rates. Our findings suggest that permafrost landscapes are undergoing geomorphic change that is impacting hydrology, ecosystems, and human infrastructure. The development of a systematic TS monitoring is urgently needed to deliver consistent and continuous exchange of data across different permafrost regions. Integration of coordinated field observations, remote sensing, and modeling of TS across a range of scales would contribute to better understanding of rapidly changing permafrost environments and resulting climate feedbacks.
• Food life history and cold storage in Greater Beringia. Part I: Preliminary interdisciplinary investigation
  Kazuyuki Saito; Yoko Kugo; Michael Koskey; Go Iwahana; Yu Hirasawa; Shirow Tatsuzawa; Yuriy Zhegusov; Yamkhin Jambaljav; Theresa Arevgaq John
  Polar Science, 41, 101092, 101092, Elsevier BV, Sep. 2024, [Peer-reviewed]
  English, Scientific journal
• Spatiotemporally continuous temperature monitoring using optical fibers (Loop1) in the internal forest areas in Alaska for the period from 2017 to 2019
  Saito, Kazuyuki; Iwahana, Go; Ikawa, Hiroki; Nagano, Hirohiko; Busey, Robert C
  Polar Data Journal, 8, 10, 22, Aug. 2024, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Permafrost conditions influence the abundance, distribution, and leaf traits of two closely related dominant shrub species (Rhododendron subsect. Ledum) in interior Alaska
  Gaku Amada; Go Iwahana; Kyotaro Noguchi; Yojiro Matsuura; Yongwon Kim; Bang‐Yong Lee; Hideki Kobayashi
  Polar Biology, 47, 10, 1039, 1054, Springer Science and Business Media LLC, 11 Jul. 2024, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Sulfur Isotope Geochemistry of Ice‐Wedges in Yakutia, East Siberia
  Hyeonjeong Jeong; Jonghan Moon; Go Iwahana; Alexander N. Fedorov; Jinho Ahn; Min Sub Sim
  Permafrost and Periglacial Processes, 35, 3, 340, 356, Wiley, 24 May 2024, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, ABSTRACT
  
  Sulfur, with its highly varying stable isotope ratio and involvement in numerous biogeochemical processes, is one of the most widely used elements as an isotopic paleoenvironmental proxy, yet the sulfur isotope ratios of ice‐wedges and their insoluble fraction remain unexplored. This study first presents the sulfur isotopic compositions of soluble sulfate, particulate organic matter (POM), and lithic particles recovered from East Siberian ice‐wedges. Soluble sulfate, primarily representing atmospheric sulfate deposition, shows comparable sulfur isotope ranges in Zyryanka and Batagay, while in Central Yakutia, ice‐wedge sulfate is more enriched in ³⁴S, consistent with the orogenic and cratonic terranes in East Siberia. Given the wedge growth during the inland winter, it is likely that sulfate aerosols were derived mainly from erosion and weathering of regional basement rocks rather than from sea salt spray or biogenic emissions. Within individual ice‐wedges, however, the sulfur isotopic composition of soluble sulfate varies by as much as 7‰, possibly reflecting changes in the relative contributions of sulfur‐isotopically distinct source regions. Beyond the origin of sulfate, greater sulfur isotope fractionations between POM and sulfate during the last glaciation suggest that sulfate may have been anaerobically reduced to sulfide and vice versa in the adjacent root zone.
• CH4 emissions from runoff water of Alaskan mountain glaciers
  Keiko Konya; Tetsuo Sueyoshi; Go Iwahana; Tomoaki Morishita; Jun Uetake; Masahide Wakita
  Scientific Reports, 14, 1, Springer Science and Business Media LLC, 09 May 2024, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Recent studies have observed high methane concentrations in runoff water and the ambient air at various glacier sites, including the Greenland Ice Sheet, the glacier forefield in Svalbard, and the ice cap in Iceland. This study extends these findings to smaller mountain glaciers in Alaska. Methane and carbon dioxide concentrations in the ambient air near the meltwater outlet, fluxes of these gases at the surface of runoff water and riverbank sediments, and dissolved methane content in the runoff water were measured at four glaciers. Three of the four glaciers showed conspicuous signals of methane emissions from runoff water, with the Castner Glacier terminus exhibiting a methane concentration three times higher than background levels, along with elevated dissolved methane levels in the runoff water. This study marks the detection of significant methane emissions from small mountain glacier runoff, contributing to the understanding that mountain glaciers also release methane into the atmosphere.
• RADIOCARBON AGES OF PLANT REMAINS IN MASSIVE GROUND ICE AND UNDERLYING SEDIMENTS OF THE BARROW PERMAFROST TUNNEL, ALASKA
  Go Iwahana; Masao Uchida; Kazuho Horiuchi; Jody Deming; Hajo Eicken; Hiroshi Ohno; Kanako Mantoku; Toshiyuki Kobayashi; Kazuyuki Saito
  Radiocarbon, 66, 5, 879, 891, Cambridge University Press (CUP), 04 Apr. 2024, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  Scientific journal, ABSTRACT
  
  Massive ground ice found in the Barrow Permafrost Tunnel at 3–7 m depths from the surface has been interpreted as an ice wedge and used to reconstruct early Holocene environmental changes. To better understand the development of this ground ice, we conducted radiocarbon dating for 34 samples of plant remains from the massive ground ice and underlying sediment layer. A significantly large gap in the measured radiocarbon ages (more than 24 ka) between massive ice and the underlying sediment layer throughout the tunnel profile suggested at least two possibilities. One is that the lower and older sediment layer had thrust upwards at the boundary between intruding ice wedge and adjacent sediment, and the growing ice had pushed the sediment sideways. Another is that erosional events had removed surface materials at about 12–36 ka BP (14–41 cal ka BP) before the overlaying sediment layer with massive ground ice developed. The overall distribution of radiocarbon ages from the massive ice supported the ice-wedge hypothesis as a formation mechanism, although our results showed several age inversions and large fluctuations. Dating of densely spaced samples revealed two ground-ice regions with similar ages around 11–11.5 and 10–10.5 ka BP divided by a relatively narrow region of transitional ages along the tunnel long-axis. This distribution may be explained by a possible misalignment between the sampling direction and the ice-wedge growth line or by intermittent ice growth with repeated cracking at more random locations than the classic ice-wedge growth model suggested.
• Excess Ground Ice Profiles in Continuous Permafrost Mapped From InSAR Subsidence
  S. Zwieback; G. Iwahana; S. Sakhalkar; R. Biessel; S. Taylor; F. J. Meyer
  Water Resources Research, 60, 2, American Geophysical Union (AGU), 08 Feb. 2024, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Excess ground ice formation and melt drive surface heave and settlement, and are critical components of the water balance in Arctic soils. Despite the importance of excess ice for the geomorphology, hydrology and biogeochemistry of permafrost landscapes, we lack fine‐scale estimates of excess ice profiles. Here, we introduce a Bayesian inversion method based on remotely sensed subsidence. It retrieves near‐surface excess ice profiles by probing the ice content at increasing depths as the thaw front deepens over summer. Ice profiles estimated from Sentinel‐1 interferometric synthetic aperture radar (InSAR) subsidence observations at 80 m resolution were spatially associated with the surficial geology in two Alaskan regions. In most geological units, the estimated profiles were ice poor in the central and, to a lesser extent, the upper active layer. In a warm summer, units with ice‐rich permafrost had elevated inferred ice contents at the base of the active layer and the (previous years') upper permafrost. The posterior uncertainty and accuracy varied with depth. In simulations, they were best (≲0.1) in the central active layer, deteriorating (≳0.2) toward the surface and permafrost. At two sites in the Brooks Foothills, Alaska, the estimates compared favorably to coring‐derived profiles down to 35 cm, while the increase in excess ice below the long‐term active layer thickness of 40 cm was only reproduced in a warm year. Pan‐Arctic InSAR observations enable novel observational constraints on the susceptibility of permafrost landscapes to terrain instability and on the controls, drivers and consequences of ground ice formation and loss.
• Evaluating the Drought Code for lowland taiga of Interior Alaska using eddy covariance measurements
  Eric A. Miller; Hiroki Iwata; Masahito Ueyama; Yoshinobu Harazono; Hideki Kobayashi; Hiroki Ikawa; Robert Busey; Go Iwahana; Eugénie S. Euskirchen
  International Journal of Wildland Fire, 32, 8, 1226, 1243, CSIRO Publishing, 30 Jun. 2023, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Background The Drought Code (DC) of the Canadian Fire Weather Index System (CFWIS) has been intuitively regarded by fire managers in Alaska, USA, as poorly representing the moisture content in the forest floor in lowland taiga forests on permafrost soils. Aims The aim of this study was to evaluate the DC using its own framework of water balance as cumulative additions of daily precipitation and substractions of actual evaporation. Methods We used eddy covariance measurements (EC) from three flux towers in Interior Alaska as a benchmark of natural evaporation. Key results The DC water balance model overpredicted drought for all 14 site-years that we analysed. Errors in water balance cumulated to 109 mm by the end of the season, which was 54% of the soil water storage capacity of the DC model. Median daily water balance was 6.3 times lower than that measured by EC. Conclusions About half the error in the model was due to correction of precipitation for canopy effects. The other half was due to dependence of the actual evaporation rate on the proportional ‘fullness’ of soil water storage in the DC model. Implications Fire danger situational awareness is improved by ignoring the DC in the CFWIS for boreal forests occurring on permafrost.
• Transient Freeze‐Thaw Deformation Responses to the 2018 and 2019 Fires Near Batagaika Megaslump, Northeast Siberia
  K. Yanagiya; M. Furuya; P. Danilov; G. Iwahana
  Journal of Geophysical Research: Earth Surface, 128, 2, American Geophysical Union (AGU), 12 Feb. 2023, [Peer-reviewed], [Last author], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Wildfires in Arctic regions impact landforms via permafrost degradation and subsequent deformation that can last for many years. However, it remains uncertain on if and how much deformations occur, and what controls their magnitude, particularly during the first couple of years. Here, we examine the transient post‐fire deformation responses near the Batagaika megaslump, which is the world's largest retrogressive thaw slump at Batagay, Sakha Republic. There were wildfires in the summers of 2018 and 2019 on the same slope, which could trigger the formation of another megaslump; many fires occurred nearby in 2019. We use interferometric synthetic aperture radar (InSAR) to measure surface displacements, including both post‐fire and span‐fire images. We also perform onsite measurements of temperature and thaw depth around the two scars near Batagaika megaslump in 2019, 2020, and 2021 and around the 2014 scar in 2019. At the three fire scars formed in 2018 and 2019, we demonstrate year‐to‐year and location‐specific changes in the amplitude of subsidence, heave, and duration. The 2018 scar shows cumulative subsidences of up to 10 cm by March 2021, more clearly than the nearby 2019 scar. On the other hand, another 2019 scar adjacent to the 2014 scar shows up to 13 cm net subsidence during the first span‐fire year, although the subsiding area is limited. These diverse transient post‐fire responses demonstrate that under the yedoma area the spatial heterogeneities of the active layer depth and the timing of fires will control subsequent thermokarst processes.
• Origin of CO₂, CH₄, and N₂O trapped in ice wedges in central Yakutia and their relationship
  Ji‐Woong Yang; Jinho Ahn; Go Iwahana; Nayeon Ko; Ji‐Hoon Kim; Kyungmin Kim; Alexander Fedorov; Sangyoung Han
  Permafrost and Periglacial Processes, 34, 1, 122, 141, Wiley, 13 Nov. 2022, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Permafrost thawing as a result of global warming is expected to foster the biological remineralization of intact organic carbon and nitrogen and release greenhouse gas (GHG) into the atmosphere, which will have positive feedback for future global warming. However, GHG budgets and their controls in permafrost ground ice are not yet fully understood. This study aims to better understand the control mechanisms of GHG in ground ice by using new gas and chemistry data. In this study, we present new data on carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) mixing ratios in three different ice wedges, Churapcha, Syrdakh, and Cyuie, located in central Yakutia, Siberia. The GHG mixing ratios in the studied ice wedges range from 0.0% to 13.8% CO₂, 1.3–91.2 ppm CH₄, and 0% and 0–1414 N₂O. In particular, all three ice wedges demonstrate that ice‐wedge samples enriched in CH₄ were depleted in N₂O mixing ratios and vice versa. N₂–O₂–Ar compositions indicate that the studied ice wedges were most likely formed by dry snow or hoarfrost, not by freezing of snow meltwater, and the O₂‐consuming biological metabolism was active. Most of the observed GHG mixing ratios cannot be explained without microbial metabolism. The inhibitory impact of denitrification products of nitrate (including N₂O) could be an important control of the ice‐wedge CH₄ mixing ratio.
• Ground Surface Displacement After a Forest Fire Near Mayya, Eastern Siberia, Using InSAR: Observation and Implication for Geophysical Modeling
  Takahiro Abe; Go Iwahana; Takeo Tadono; Yoshihiro Iijima
  Earth and Space Science, 9, 11, American Geophysical Union (AGU), 26 Oct. 2022, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Forest fires significantly impact permafrost degradation in the subarctic regions. However, interannual and seasonal variations in surface deformation due to permafrost thawing in burned areas were poorly understood. Measuring the ground surface displacement in fire scars helps us understand the freeze‐thaw dynamics of near‐surface ground and predict the future state, particularly in ice‐rich permafrost regions. This study used the L‐ and C‐band interferometric synthetic aperture radar technique to reveal interannual subsidence and seasonal thaw settlement/frost heave in a fire scar near Mayya, Sakha Republic in Eastern Siberia burned in 2013. We found that the cumulative subsidence was up to 7 cm between 2014 and 2020, most of which had occurred by 2016. The magnitude of seasonal thaw settlement and frost heave varied each year from 2017 to 2020 after the fire, but the interannual change in frost heave corresponded to the temporal variation in precipitation during the thawing season from 2017 to 2020. This suggests that the precipitation amount during the thawing season is related to the magnitude of segregation‐ice formation in the sediments, which determines the frost heave amount. The observed seasonal displacements could not be quantitatively explained by models inferred from the Stefan's equation and volume changes associated with ice‐water phase change. This implies that other models associated with segregated ice (ice lens) formation/thaw are required to explain the observed seasonal displacement.
• Assessing and projecting surface air temperature conditions required to sustain permafrost in Japan
  Tokuta Yokohata; Go Iwahana; Kazuyuki Saito; Noriko N. Ishizaki; Taiga Matsushita; Tetsuo Sueyoshi
  Progress in Earth and Planetary Science, 9, 1, 02 Aug. 2022, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Methane flux around the Gulkana Glacier terminus, Alaska summer 2019
  Konya, K; G. Iwahana; T. Sueyoshi; T. Morishita; T. Abe
  Polar Data Journal, 6, 32, 42, Aug. 2022, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
• Understanding formation of ice wedges and origin of trapped greenhouse gas at Zyryanka, Northeastern Siberia 
  Nayeon Ko; Hansu Park; Hyejung Jung; Go Iwahana; Alexander Fedorov; Jinho Ahn
  Copernicus GmbH, 27 Mar. 2022
  <p>Multiple geochemical analyses may help us better constrain the ice-wedge formation and in-situ greenhouse gas (GHG) production mechanisms. Here we present new results from ice-wedge ice sampled at Zyryanka, Northeastern Siberia (65°93’N, 150°89’E). The plant remains and CO<sub>2</sub> gas were analyzed for <sup>14</sup>C dating, and we obtained from 810 to 1750 years before 1950 CE for the Zyryanka ice wedge. δ(N<sub>2</sub>/Ar) of the ice wedges ranges from -17.51 to -3.53 % with regard to modern air, indicating that the Zyryanka ice wedge was formed by both liquid water and dry snow. On the other hand, the δ(O<sub>2</sub>/Ar) value of the Zyryanka ice wedges ranges from -72.88 to -37.58 % with regard to modern air, implying oxygen gas was consumed considerably by respiration of microorganisms in the ice-wedge ice. We also observed correlations among the three greenhouse gas species and oxygen gas concentrations. N<sub>2</sub>O and CO<sub>2</sub> concentrations show a strong positive correlation (r<em> </em>= 0.94, p=0.01). We also found that the melting fraction (estimated from N<sub>2</sub>/Ar) is positively correlated with CO2 (r=0.81, p=0.01) and CH<sub>4</sub> (r=0.87, p<0.05). Furthermore, O<sub>2</sub> concentration is negatively correlated with the CH<sub>4</sub> concentrations (r = -0.41, p<0.05) which may imply that CH<sub>4</sub> production is associated with biological oxygen consumption. The δ<sup>18</sup>O of ice melt ranges from -28.6 to -19.1 ‰ for the ice wedge and adjacent soil samples, showing a symmetric structure with low δ<sup>18</sup>O values in the ice wedge parts and high in the adjacent soils. Comparing with the δ<sup>18</sup>O value of modern precipitation in the Zyryanka region, it can be inferred that the ice wedge was mainly formed by filling with cold seasonal precipitation. Our study shows that the gas mixing ratios in ice wedges and water stable isotope analysis may help better understanding the biogeochemical environments during and after the formation of ice wedges.</p>
• Climatic assessment of circum-Arctic permafrost zonation over the last 122 kyr
  Kazuyuki Saito; Jun'ichi Okuno; Hirokazu Machiya; Go Iwahana; Hiroshi Ohno; Tokuta Yokohata
  Polar Science, 31, 100765, 100765, Mar. 2022, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Surface displacement induced by seasonal ground thaw, measured by synthetic aperture radar in the Daisetsu Mountains, Japan
  Takahiro ABE; Go IWAHANA; Toshio SONE; Masao UCHIDA
  Journal of the Japanese Society of Snow and Ice, 84, 1, 13, 27, Japanese Society of Snow and Ice, 15 Jan. 2022, [Peer-reviewed], ［Internationally co-authored］, [Domestic magazines]
  Japanese, Scientific journal
• Quantitative Separation of Precipitation and Permafrost Waters Used for Evapotranspiration in a Boreal Forest: A Numerical Study Using Tracer Model
  Hotaek Park; Masahiro Tanoue; Atsuko Sugimoto; Kimpei Ichiyanagi; Go Iwahana; Tetsuya Hiyama
  Journal of Geophysical Research: Biogeosciences, 126, 12, American Geophysical Union (AGU), 10 Dec. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Projections of surface air temperature required to sustain permafrost and importance of adaptation to climate change in the Daisetsu Mountains, Japan
  Tokuta Yokohata; Go Iwahana; Toshio Sone; Kazuyuki Saito; Noriko N. Ishizaki; Takahiro Kubo; Hiroyuki Oguma; Masao Uchida
  Scientific Reports, 11, 1, Springer Science and Business Media LLC, 30 Jul. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Permafrost is known to occur in high mountainous areas such as the Daisetsu Mountains in Japan, which are located at the southernmost limit of the permafrost distribution in the world. In this study, areas with climatic conditions suitable for sustaining permafrost in the Daisetsu Mountains are projected using bias-corrected and downscaled climate model outputs and statistical relationships between surface air temperatures and permafrost areas. Using freezing and thawing indices, the size of the area in the Daisetsu Mountains where climatic conditions were suitable for permafrost were estimated to be approximately 150 km² in 2010. Under the RCP8.5 scenario, this area is projected to decrease to about 30 km² by 2050 and it is projected to disappear by around 2070. Under the RCP2.6 scenario, the area is projected to decrease to approximately 20 km² by 2100. The degradation of mountain permafrost could potentially affect the stability of trekking trails due to slope displacement, and it may also have deleterious effects on current alpine ecosystems. It is therefore important to accurately monitor changes in the mountain ecosystem environment and to implement measures to adapt to an environment that is projected to change significantly in the future.
• Applications of UAVs in Cold Region Ecological and Environmental Studies
  Shuhua Yi; Go Iwahana; Yu Qin; Yi Sun
  Remote Sensing, 13, 13, 2472, 2472, MDPI AG, 24 Jun. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Lightweight unmanned aerial vehicles (UAVs) have been developed rapidly due to the miniaturization of aircraft components and the low cost of various sensors, as well as embedded computers, and have become a commonly used platform for ecological and environmental studies [...]
• Mapping the Main Characteristics of Permafrost on the Basis of a Permafrost-Landscape Map of Yakutia Using GIS
  Alyona A. Shestakova; Alexander N. Fedorov; Yaroslav I. Torgovkin; Pavel Y. Konstantinov; Nikolay F. Vasyliev; Svetlana V. Kalinicheva; Vera V. Samsonova; Tetsuya Hiyama; Yoshihiro Iijima; Hotaek Park; Go Iwahana; Alexey N. Gorokhov
  Land, 10, 5, 462, 462, MDPI AG, 27 Apr. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, The purpose of this article was to compile four separate digital thematic maps of temperature and ice content of permafrost, the active layer thickness, and cryogenic processes in Yakutia as a basis for assessing changes to modern climate changes and anthropogenic disturbances. In this work, materials on permafrost were used, serving as the basis for compiling a permafrost landscape map of the Republic of Sakha (Yakutia). The maps were compiled using ArcGIS software, which supports attribute table mapping. The ground temperature and active layer thickness maps reflected landscape zonality and regional differences. Peculiarities of genetic types of Quaternary deposits and climatic conditions reflected the ice content of surface sediments and cryogenic process distribution maps. One of the most common is ground temperatures from −2.1 to −4.0 °C, which were found to occupy about 37.4% of the territory of Yakutia. More than half of the region was found to be occupied by permafrost landscapes with a limited thickness of the active layer up to 1.1 m. Ice-rich permafrost (more than 0.4 in ice content) was found to be typical for about 40% of the territory. Thermokarst is the most hazardous process that occurs in half of Yakutia.
• Arctic tundra shrubification: a review of mechanisms and impacts on ecosystem carbon balance
  Zelalem A Mekonnen; William J Riley; Logan T Berner; Nicholas J Bouskill; Margaret S Torn; Go Iwahana; Amy L Breen; Isla H Myers-Smith; Mariana García Criado; Yanlan Liu; Eugénie S Euskirchen; Scott J Goetz; Michelle C Mack; Robert F Grant
  Environmental Research Letters, 16, 5, 053001, 053001, IOP Publishing, 23 Apr. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Vegetation composition shifts, and in particular, shrub expansion across the Arctic tundra are some of the most important and widely observed responses of high-latitude ecosystems to rapid climate warming. These changes in vegetation potentially alter ecosystem carbon balances by affecting a complex set of soil–plant–atmosphere interactions. In this review, we synthesize the literature on (a) observed shrub expansion, (b) key climatic and environmental controls and mechanisms that affect shrub expansion, (c) impacts of shrub expansion on ecosystem carbon balance, and (d) research gaps and future directions to improve process representations in land models. A broad range of evidence, includingin-situobservations, warming experiments, and remotely sensed vegetation indices have shown increases in growth and abundance of woody plants, particularly tall deciduous shrubs, and advancing shrublines across the circumpolar Arctic. This recent shrub expansion is affected by several interacting factors including climate warming, accelerated nutrient cycling, changing disturbance regimes, and local variation in topography and hydrology. Under warmer conditions, tall deciduous shrubs can be more competitive than other plant functional types in tundra ecosystems because of their taller maximum canopy heights and often dense canopy structure. Competitive abilities of tall deciduous shrubs vs herbaceous plants are also controlled by variation in traits that affect carbon and nutrient investments and retention strategies in leaves, stems, and roots. Overall, shrub expansion may affect tundra carbon balances by enhancing ecosystem carbon uptake and altering ecosystem respiration, and through complex feedback mechanisms that affect snowpack dynamics, permafrost degradation, surface energy balance, and litter inputs. Observed and projected tall deciduous shrub expansion and the subsequent effects on surface energy and carbon balances may alter feedbacks to the climate system. Land models, including those integrated in Earth System Models, need to account for differences in plant traits that control competitive interactions to accurately predict decadal- to centennial-scale tundra vegetation and carbon dynamics.
• Intra‐ice and intra‐sediment cryopeg brine occurrence in permafrost near Utqiaġvik (Barrow)
  Go Iwahana; Zachary S. Cooper; Shelly D. Carpenter; Jody W. Deming; Hajo Eicken
  Permafrost and Periglacial Processes, 32, 3, 427, 446, Wiley, 11 Mar. 2021, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  Cryopeg is a layer within permafrost containing a significant amount of cryotic unfrozen water due to dissolved salts. To explore the origin and development of cryopeg and associated brines found near Utqiaġvik, we sampled extensively within the Barrow Permafrost Tunnel. We found two types of cryopeg brines based on their distinctive locations: (a) intra‐ice brine (IiB), entirely bounded by massive ground ice, and not previously observed in the Northern Hemisphere; and (b) intra‐sediment brine (IsB), found as expected in unfrozen sediments within permafrost. The encountered IiBs were situated in small ellipsoidal or more complex shaped pockets within the massive ice at roughly atmospheric pressure. Radiocarbon dating suggests that the IiB segregated from IsB‐bearing cryopeg beneath the massive ice at about 11 ka BP, at the earliest. From geochemical analyses, IsB lenses were interpreted as having developed through repeated evaporation and cryoconcentration of seawater in a lagoonal environment, then isolated when the surrounding sediment froze and became covered by an upper sediment unit around 40 ka BP or earlier. The discovery of IiB and development of origin scenarios for both brine types validate the importance of high‐resolution sampling as enabled by the unique facility of a permafrost tunnel.
• Impacts of climate-induced permafrost degradation on vegetation: A review
  Xiao-Ying Jin; Hui-Jun Jin; Go Iwahana; Sergey S. Marchenko; Dong-Liang Luo; Xiao-Ying Li; Si-Hai Liang
  Advances in Climate Change Research, 12, 1, 29, 47, Elsevier BV, Feb. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Numerical model to simulate long-term soil organic carbon and ground ice budget with permafrost and ice sheets (SOC-ICE-v1.0)
  Kazuyuki Saito; Hirokazu Machiya; Go Iwahana; Tokuta Yokohata; Hiroshi Ohno
  Geoscientific Model Development, 14, 1, 521, 542, 27 Jan. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska
  Emily M. Bristol; Craig T. Connolly; Thomas D. Lorenson; Bruce M. Richmond; Anastasia G. Ilgen; R. Charles Choens; Diana L. Bull; Mikhail Kanevskiy; Go Iwahana; Benjamin M. Jones; James W. McClelland
  Frontiers in Earth Science, 8, Frontiers Media SA, 08 Jan. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three permafrost cores (4.5–7.5 m long) along a geomorphic gradient near Drew Point, Alaska, where recent erosion rates average 17.2 m year⁻¹. Down-core patterns indicate that organic-rich soils and lacustrine sediments (12–45% total organic carbon; TOC) in the active layer and upper permafrost accumulated during the Holocene. Deeper permafrost (below 3 m elevation) mainly consists of Late Pleistocene marine sediments with lower organic matter content (∼1% TOC), lower C:N ratios, and higher δ¹³C values. Radiocarbon-based estimates of organic carbon accumulation rates were 11.3 ± 3.6 g TOC m⁻² year⁻¹during the Holocene and 0.5 ± 0.1 g TOC m⁻² year⁻¹during the Late Pleistocene (12–38 kyr BP). Within relict marine sediments, porewater salinities increased with depth. Elevated salinity near sea level (∼20–37 in thawed samples) inhibited freezing despite year-round temperatures below 0°C. We used organic matter stock estimates from the cores in combination with remote sensing time-series data to estimate carbon fluxes for a 9 km stretch of coastline near Drew Point. Erosional fluxes of TOC averaged 1,369 kg C m⁻¹ year⁻¹during the 21st century (2002–2018), nearly doubling the average flux of the previous half-century (1955–2002). Our estimate of the 21st century erosional TOC flux year⁻¹from this 9 km coastline (12,318 metric tons C year⁻¹) is similar to the annual TOC flux from the Kuparuk River, which drains a 8,107 km²area east of Drew Point and ranks as the third largest river on the North Slope of Alaska. Total nitrogen fluxes via coastal erosion at Drew Point were also quantified, and were similar to those from the Kuparuk River. This study emphasizes that coastal erosion represents a significant pathway for carbon and nitrogen trapped in permafrost to enter modern biogeochemical cycles, where it may fuel food webs and greenhouse gas emissions in the marine environment.
• Seasonal and Interannual Ground-Surface Displacement in Intact and Disturbed Tundra along the Dalton Highway on the North Slope, Alaska
  Go Iwahana; Robert Busey; Kazuyuki Saito
  Land, 10, 1, 22, 22, MDPI AG, 29 Dec. 2020, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Model improvement and future projection of permafrost processes in a global land surface model
  Tokuta Yokohata; Kazuyuki Saito; Kumiko Takata; Tomoko Nitta; Yusuke Satoh; Tomohiro Hajima; Tetsuo Sueyoshi; Go Iwahana
  Progress in Earth and Planetary Science, 7, 1, Springer Science and Business Media LLC, 13 Nov. 2020, [Peer-reviewed], [Last author], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract
  
  To date, the treatment of permafrost in global climate models has been simplified due to the prevailing uncertainties in the processes involving frozen ground. In this study, we improved the modeling of permafrost processes in a state-of-the-art climate model by taking into account some of the relevant physical properties of soil such as changes in the thermophysical properties due to soil freezing. As a result, the improved version of the global land surface model was able to reproduce a more realistic permafrost distribution at the southern limit of the permafrost area by increasing the freezing of soil moisture in winter. The improved modeling of permafrost processes also had a significant effect on future projections. Using the conventional formulation, the predicted cumulative reduction of the permafrost area by year 2100 was approximately 60% (40–80% range of uncertainty from a multi-model ensemble) in the RCP8.5 scenario, while with the improved formulation, the reduction was approximately 35% (20–50%). Our results indicate that the improved treatment of permafrost processes in global climate models is important to ensuring more reliable future projections.
• Future projection of greenhouse gas emissions due to permafrost degradation using a simple numerical scheme with a global land surface model
  Tokuta Yokohata; Kazuyuki Saito; Akihiko Ito; Hiroshi Ohno; Katsumasa Tanaka; Tomohiro Hajima; Go Iwahana
  Progress in Earth and Planetary Science, 7, 1, Springer Science and Business Media LLC, 02 Oct. 2020, [Peer-reviewed], [Last author], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Surface displacement revealed by L-band InSAR analysis in the Mayya area, Central Yakutia, underlain by continuous permafrost
  Abe, Takahiro; Iwahana, Go; Efremov; Petr V.; Desyatkin; Alexey R.; Kawamura, Takumi; Fedorov, Alexander; Zhegusov, Yuri; Yanagiya, Kazuki; Tadono, Takeo
  Earth, Planets and Space, 72, 1, 138, 138, Sep. 2020, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Mapping simulated circum-Arctic organic carbon, ground ice, and vulnerability of ice-rich permafrost to degradation
  Kazuyuki Saito; Hirokazu Machiya; Go Iwahana; Hiroshi Ohno; Tokuta Yokohata
  Progress in Earth and Planetary Science, 7, 1, 22 Jul. 2020, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Brief Communication: The reliability of gas extraction techniques for analysing CH₄ and N₂O compositions in gas trapped in permafrost ice wedges
  Ji-Woong Yang; Jinho Ahn; Go Iwahana; Sangyoung Han; Kyungmin Kim; Alexander Fedorov
  The Cryosphere, 14, 4, 1311, 1324, Copernicus GmbH, 23 Apr. 2020, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal, Abstract. Methane (CH4) and nitrous oxide (N2O) compositions in ground ice may provide information on their production mechanisms inpermafrost. However, existing gas extraction methods have not been well tested. We tested conventional wet and dry gas extraction methods using icewedges from Alaska and Siberia, finding that both methods can extract gas from the easily extractable parts of the ice (e.g. gas bubbles) and yieldsimilar results for CH4 and N2O mixing ratios. We also found insignificant effects of microbial activity during wetextraction. However, both techniques were unable to fully extract gas from the ground ice, presumably because gas molecules adsorbed onto or enclosedin soil aggregates are not easily extractable. Estimation of gas production in a subfreezing environment of permafrost should consider such incompletegas extraction.
• Measurements of beryllium isotopes in ice wedges in Alaska
  Kazuho Horiuchi; Hiroshi Ohno; Go Iwahana; Yoshinori Iizuka; Hiroyuki Matsuzaki
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 459, 64, 70, Elsevier BV, Nov. 2019, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Distinctive microbial communities in subzero hypersaline brines from Arctic coastal sea ice and rarely sampled cryopegs
  Zachary S Cooper; Josephine Z Rapp; Shelly D Carpenter; Go Iwahana; Hajo Eicken; Jody W Deming
  FEMS Microbiology Ecology, 95, 12, Oxford University Press (OUP), 18 Oct. 2019, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Ion concentrations in ice wedges: An innovative approach to reconstruct past climate variability
  Yoshinori Iizuka; Chihiro Miyamoto; Sumito Matoba; Go Iwahana; Kazuho Horiuchi; Yoshio Takahashi; Naoya Kanna; Koji Suzuki; Hiroshi Ohno
  Earth and Planetary Science Letters, 515, 58, 66, Elsevier BV, Jun. 2019, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Technical advances in measuring greenhouse gas emissions from thawing permafrost soils in the laboratory
  Seiichiro Yonemura; Masao Uchida; Go Iwahana; Yongwon Kim; Kenji Yoshikawa
  Polar Science, 19, 137, 145, Mar. 2019, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Multi-year effect of wetting on CH 4 flux at taiga-Tundra boundary in northeastern Siberia deduced from stable isotope ratios of CH 4
  Ryo Shingubara; Atsuko Sugimoto; Jun Murase; Go Iwahana; Shunsuke Tei; Maochang Liang; Shinya Takano; Tomoki Morozumi; Trofim C. Maximov
  Biogeosciences, 16, 3, 755, 768, Copernicus GmbH, 11 Feb. 2019, [Peer-reviewed]
  Scientific journal
• A decade of remotely sensed observations highlight complex processes linked to coastal permafrost bluff erosion in the Arctic
  Benjamin M Jones; Louise M Farquharson; Carson A Baughman; Richard M Buzard; Christopher D Arp; Guido Grosse; Diana L Bull; Frank Günther; Ingmar Nitze; Frank Urban; Jeremy L Kasper; Jennifer M Frederick; Matthew Thomas; Craig Jones; Alejandro Mota; Scott Dallimore; Craig Tweedie; Christopher Maio; Daniel H Mann; Bruce Richmond; Ann Gibbs; Ming Xiao; Torsten Sachs; Go Iwahana; Mikhail Kanevskiy; Vladimir E Romanovsky
  Environmental Research Letters, 13, 11, 115001, 115001, IOP Publishing, 25 Oct. 2018, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Links between annual surface temperature variation and land cover heterogeneity for a boreal forest as characterized by continuous, fibre-optic DTS monitoring
  Kazuyuki Saito; Go Iwahana; Hiroki Ikawa; Hirohiko Nagano; Robert C. Busey
  Geoscientific Instrumentation, Methods and Data Systems, 7, 3, 223, 234, Copernicus GmbH, 31 Jul. 2018, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Tundra fire alters vegetation patterns more than the resultant thermokarst
  Shiro Tsuyuzaki; Go Iwahana; Kazuyuki Saito
  Polar Biology, 41, 4, 753, 761, Springer Science and Business Media LLC, 28 Dec. 2017, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• 北海道における冬期土壌凍結深の測定を通したアウトリーチ活動
  原田鉱一郎; 吉川謙二; 岩花剛; J.Stanilovskaya; 澤田結基; 曽根敏雄
  北海道の雪氷, 36, 7, 8, Sep. 2017, [Peer-reviewed], ［Internationally co-authored］, [Domestic magazines]
  Japanese, Scientific journal
• Outreach program by measurements of frost depth (6)
  Harada Koichiro; Yoshikawa Kenji; Iwahana Go; Stanilovskaya Julia; Yuki Sawada; Sone Toshio
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2017, 183, 183, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, 2017
  Japanese
• Geomorphological and geochemistry changes in permafrost after the 2002 tundra wildfire in Kougarok, Seward Peninsula, Alaska
  Go Iwahana; Koichiro Harada; Masao Uchida; Shiro Tsuyuzaki; Kazuyuki Saito; Kenji Narita; Keiji Kushida; Larry D. Hinzman
  JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE, 121, 9, 1697, 1715, Sep. 2016, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Endurance of larch forest ecosystems in eastern Siberia under warming trends
  Hisashi Sato; Hideki Kobayashi; Go Iwahana; Takeshi Ohta
  ECOLOGY AND EVOLUTION, 6, 16, 5690, 5704, Aug. 2016, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Variability of Permafrost and Landscape Conditions Following Clear Cutting of Larch Forest in Central Yakutia
  Alexander N. Fedorov; Go Iwahana; Pavel Y. Konstantinov; Takashi Machimura; Radomir N. Argunov; Peter V. Efremov; Larry M.C. Lopez; Fumiaki Takakai
  Permafrost and Periglacial Processes, 28, 1, 331, 338, 02 Jun. 2016, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• InSAR Detection and Field Evidence for Thermokarst after a Tundra Wildfire, Using ALOS-PALSAR
  Go Iwahana; Masao Uchida; Lin Liu; Wenyu Gong; Franz Meyer; Richard Guritz; Tsutomu Yamanokuchi; Larry Hinzman
  Remote Sensing, 8, 3, 218, 218, 08 Mar. 2016, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Snowmelt and the hydrological interaction of forest-grassland ecosystems in Central Yakutia, eastern Siberia
  M. L. Lopez Caceres; F. Takakai; G. Iwahana; A. N. Fedorov; Y. Iijima; R. Hatano; M. Fukuda
  HYDROLOGICAL PROCESSES, 29, 14, 3074, 3083, Jul. 2015, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Outreach program by measurements of frost depth (4)
  HARADA Koichiro; YOSHIKAWA Kenji; IWAHANA Go; STANILOVSKAYA Julia; SAWADA Yuki
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2015, 84, 84, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, 2015
  Japanese
• Geocryological characteristics of the upper permafrost in a tundra-forest transition of the Indigirka River Valley, Russia
  Go Iwahana; Shinya Takano; Roman E. Petrov; Shunsuke Tei; Ryo Shingubara; Trofini C. Maximov; Alexander N. Fedorov; Alexey R. Desyatkin; Anatoly N. Nikolaev; Roman V. Desyatkin; Atsuko Sugimoto
  POLAR SCIENCE, 8, 2, 96, 113, Jun. 2014, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Estimating the water balance of a thermokarst lake in the middle of the Lena River basin, eastern Siberia
  A. N. Fedorov; P. P. Gavriliev; P. Y. Konstantinov; T. Hiyama; Y. Iijima; G. Iwahana
  ECOHYDROLOGY, 7, 2, 188, 196, Apr. 2014, [Peer-reviewed], [Last author], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• A Review of Studies on Yedoma Suite (Part 2) : Paleoenvironmental information from the Yedoma deposits
  IWAHANA Go
  雪氷 : 日本雪氷協會雜誌, 75, 5, 353, 364, 日本雪氷学会, 15 Sep. 2013, [Peer-reviewed], [Lead author], [Domestic magazines]
  Japanese, Scientific journal
• A Review of Studies on Yedoma Suite (Part 1) : Overview of the research history and connection to climate change
  IWAHANA GO
  雪氷 : 日本雪氷協會雜誌, 75, 5, 343, 352, 日本雪氷学会, 15 Sep. 2013, [Peer-reviewed], [Lead author], [Domestic magazines]
  Japanese, Scientific journal
• Development and Internal Structure of a Palsa along the Denali Highway, Alaska
  Iwahana Go; Uchida Masao; Kondo Miyuki; Yoshikawa Kenji; Hinzman Larry
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2013, 31, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, 2013
  Japanese
• Environmental consciousness of local people of yakutia under global climate change
  Yury I. Zhegusov; Stanislav M. Ksenofontov; Trofim Ch. Maximov; Atsuko Sugimoto; Go Iwahana
  Causes, Impacts and Solutions to Global Warming, 251, 260, Springer New York, 01 Jan. 2013, [Peer-reviewed], [Last author], ［Internationally co-authored］, [International Magazine]
  English, In book
• Internal Structure of a Lithalsa in the Akkol Valley, Russian Altai Mountains
  Go Iwahana; Kotaro Fukui; Nikolai Mikhailov; Oleg Ostanin; Yoshiyuki Fujii
  PERMAFROST AND PERIGLACIAL PROCESSES, 23, 2, 107, 118, Apr. 2012, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Year-round Monitoring of Shallow Ground Temperatures at High Altitudes of Mt. Fuji with a Critical Discussion on the Popular Belief of Rapid Permafrost Degradation
  Atsuhi Ikeda; Go Iwahana; Tetsuo Sueyoshi
  Journal of Geography (Chigaku Zasshi), 121, 2, 306, 331, Tokyo Geographical Society, Feb. 2012, [Peer-reviewed], [Domestic magazines]
  Japanese, Scientific journal, On September 2010, the Japanese mass media reported that permafrost had disappeared throughout the altitudes of 3300–3600 m asl. on the south-facing slope of Mt. Fuji (3776 m asl.) within 12 years because of climatic warming. However, no evidence (data and analyses) has been published in scientific journals. In this paper, we show ground freeze-thaw patterns above the tree line of Mt. Fuji based on recent year-round records of temperatures at shallow depths at 22 sites. The shallow ground temperatures became significantly warmer from the 2008–2009 period to the 2009–2010 period because the latter period had irregular snow accumulation at several sites and extremely sunny hot summer. The snow cover on Mt. Fuji generally prevented the ground from cooling rather than from warming. In addition, records for some locations show rapid ground warming in late summer, which accompanied heavy rainfall events. The mean annual temperatures at the ground surface on the south-facing slope were 1.5 to 3°C higher than those on the north-facing slope at the same altitude. Considering these characteristics, we interpret that the presence of permafrost is probable only at 5 sites on north- to west-facing windy locations above 3500 m asl., although studies in the 1970s suggest that the lower boundary lay at around 3000 m asl. on both north- and south-facing slopes. However, it is clear that, in the 1970s, the estimation of permafrost distribution on Mt. Fuji was based not on thaw depths at the end of thawing period (late September to mid October), but on those in the middle of thawing period (late July to August). The resulting overestimation of the permafrost distribution may have led to tales of extremely rapid permafrost degradation. Permafrost research on Mt. Fuji is still at its initial stage and long-term monitoring of ground temperatures is required to evaluate the impacts of changes of climate and volcanic activity on the surrounding environment.
• Monitoring of 3m-profiles of ground temperature on the summit area of Mt. Fuji (2008-2010) : Toward elucidation of permafrost occurrence and its long-term change
  IWAHANA Go; IKEDA Atsushi; FUKUI Kotaro; SAITO Kazuyuki; SUEYOSHI Tetsuo; HARADA Koichiro; SAWADA Yuki
  雪氷 : 日本雪氷協會雜誌, 73, 2, 119, 131, 日本雪氷学会, Mar. 2011, [Peer-reviewed], [Lead author], [Domestic magazines]
  Japanese
• Use of automated recorders (data loggers) in permafrost temperature monitoring
  Konstantinov, P.Y.; Fedorov, A.N.; Machimura, T.; Iwahana, G.; Yabuki, H.; Iijima, Y.; Costard, F.
  Earth's Cryosphere, 15, 1, 23, 32, 01 Jan. 2011, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  Russian, Scientific journal
• Effect of increased rainfall on water dynamics of larch (Larix cajanderi) forest in permafrost regions, Russia: an irrigation experiment
  M. L. Lopez C; T. Shirota; G. Iwahana; T. Koide; T. C. Maximov; M. Fukuda; H. Saito
  JOURNAL OF FOREST RESEARCH, 15, 6, 365, 373, Dec. 2010, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Effects of changes in the soil environment associated with heavy precipitation on soil greenhouse gas fluxes in a Siberian larch forest near Yakutsk
  Takahiro Koide; Hideyuki Saito; Tetsuoh Shirota; Go Iwahana; M. Larry Lopez C; Trofim C. Maximov; Shuichi Hasegawa; Ryusuke Hatano
  SOIL SCIENCE AND PLANT NUTRITION, 56, 4, 645, 662, Aug. 2010, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Comparison of carbon and water vapor exchange of forest and grassland in permafrost regions, Central Yakutia, Russia
  M. L. Lopez C; E. Gerasimov; T. Machimura; F. Takakai; G. Iwahana; A. N. Fedorov; M. Fukuda
  AGRICULTURAL AND FOREST METEOROLOGY, 148, 12, 1968, 1977, Dec. 2008, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Slab avalanches occurred at Mt. Kamihorokamettoku, Tokachi Mountain Range, in Hokkaido in November 2007
  Ozeki, T; A. Hachikubo; G. Iwahana; K. Nakamura; K. Higuchi; H. Onishi; D. Sasaki; E. Akitaya
  Seppyo, 70, 6, 571, 580, 日本雪氷学会, Nov. 2008, [Peer-reviewed], [Domestic magazines]
  Japanese, Scientific journal
• Micrometeorological measurements on mountain permafrost in Daisetsu Mountains, Hokkaido, Japan.
  Iwahana, G; Sawada, Y; Ishikawa, M; Katamura, F; Sone, T; Sueyoshi, T; Harada, K
  Ninth International Conference on Permafrost, 1, 6, 809, 814, 2008, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  English, International conference proceedings
• Interannual environmental-soil thawing rate variation and its control on transpiration from Larix cajanderi, Central Yakutia, Eastern Siberia
  M. L. C. Lopez; H. Saito; Y. Kobayashi; T. Shirota; G. Iwahana; T. C. Maximov; M. Fukuda
  JOURNAL OF HYDROLOGY, 338, 3-4, 251, 260, May 2007, [Peer-reviewed]
  English, Scientific journal
• The lower limit of mountain permafrost in the Russian Altai Mountains
  Kotaro Fukui; Yoshiyuki Fujii; Nikolai Mikhailov; Oleg Ostanin; Go Iwahana
  PERMAFROST AND PERIGLACIAL PROCESSES, 18, 2, 129, 136, Apr. 2007, [Peer-reviewed], [Last author], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• 永久凍土と活動層のリモートセンシング (衛星観測特集)
  串田圭司; 原田鉱一郎; 森淳子; 岩花剛; 澤田結基; 片村文崇; 福田正己
  雪氷（日本雪氷学会誌）, 69, 2, 221-228, 228, The Japanese Society of Snow and Ice, Mar. 2007, [Peer-reviewed], [Domestic magazines]
  Japanese, Scientific journal, 凍土に関わるリモートセンシングの研究をレビューした.凍土は生態系と密接な関係がある.凍土一生態系システムは大気との熱・水収支および温室効果ガス収支に関わっている.永久凍土地帯で予想されている温暖化とそのフィードバックを考えると,凍土の変化の広域把握はますます重要性を増す.凍土はたいていの場合,上空から直接見ることはできない.マイクロ波のPバンド(周波数320MHz,波長0.9m)を用いてもせいぜい土中1mの深さまでの情報しか得ることができない.こうした意味で,凍土のリモートセンシングは限られたものであるという見方もあろう.しかし別の見方をすれば,それは,凍土と密接な関係のある1)凍土上の生態系のリモートセンシング,2)地表面の凍結融解のリモートセンシング,3)凍土上部もしくは活動層のリモートセンシング,4)融解湖のリモートセンシング,5)マイクロ波リモートセンシングと地中レーダの統合,6)リモートセンシングを基礎にした地理情報システムによる総合的な解析,から成る広範で学際的な研究分野であると言える.
• Micrometeorological Measurements in the Daisetsu Mountains
  IWAHANA Go
  Geographical Studies, 2006, 81, 51, 54, The Hokkaido Geographical Society, 2006, [Peer-reviewed], [Lead author], [Domestic magazines]
  Japanese
• Influence of forest clear‐cutting on the thermal and hydrological regime of the active layer near Yakutsk, eastern Siberia
  Go Iwahana; Takashi Machimura; Yoshikazu Kobayashi; Alexander N. Fedorov; Pavel Y. Konstantinov; Masami Fukuda
  Journal of Geophysical Research: Biogeosciences, 110, G2, 26 Oct. 2005, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  Scientific journal
• Thermal conductivity of soils in the active layer of Eastern Siberia
  A Brouchkov; M Fukuda; G Iwahana; Y Kobayashi; P Konstantinov
  PERMAFROST AND PERIGLACIAL PROCESSES, 16, 2, 217, 222, Apr. 2005, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Change of carbon dioxide budget during three years after deforestation in eastern Siberia larch forest.
  Machimura T; Kobayashi Y; Iwahana G; Hirano T; Lopez L; Fukuda M; Fedorov A
  Journal of Agricultural Meteorology, 60, 5, 653, 656, 日本農業気象学会, 2005, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
  English, Scientific journal
• Energy and water budgets of the active layer in a larch forest and disturbed forest sites, near Yakutsk, Eastern Siberia
  IWAHANA Go; MACHIMURA Takashi; KOBAYASHI Yoshikazu; FUKUDA Masami
  Journal of the Japanese Association of Snow and Ice, 66, 2, 163, 175, The Japanese Society of Snow and Ice, 15 Mar. 2004, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [Domestic magazines]
  Japanese, Scientific journal, Thermal and hydrological dynamics of the active layer were monitored during the thawing period from May to September 2000, near Yakutsk, Eastern Siberia. This region is characterized by continuous permafrost and boreal forest (Taiga). The aims were to clarify the characteristics of the heat and water budgets in the active layer, and to assess the influence of forest disturbance on permafrost, based on field observations in disturbed and undisturbed forests. Heat and water budgets of the active layer were analyzed and compared at a mature larch forest site and a disturbed site, which experienced wildfire and clear-cutting 11 years before these observations. Results of the heat budget analysis indicated that the storage of latent heat was the largest component of the heat budget in the active layer. Despite larger ground heat flux observed at the disturbed site, the difference between thaw depth at the disturbed and forest sites was small. This result was attributed to the higher initial ground ice content at the disturbed site where more latent energy of fusion is required to deepen the thawing layer. Water budget analysis showed that total evapotranspiration at the disturbed site was 75% of that at the undisturbed forest site for the period June-September 2000; thus, more soil water tends to be stored at the disturbed site than at the undisturbed forest site. Finally, the conclusion of this study is that soil water content in the active layer is the determinant factor of maximum thaw depth in this region.
• Thermokarst as a short-term permafrost disturbance, Central Yakutia
  A Brouchkov; M Fukuda; A Fedorov; P Konstantinov; G Iwahana
  PERMAFROST AND PERIGLACIAL PROCESSES, 15, 1, 81, 87, Jan. 2004, [Peer-reviewed], [Last author]
  English, Scientific journal
• Surface Pollen Data from Different Vegetation Types in Northeastern Russia: The Basis for Reconstruction of Vegetation
  五十嵐八枝子; 岩花剛; 仙頭宣幸; 露崎史朗; 佐藤利幸
  第四紀研究, 42, 6, 2003, [Peer-reviewed], [Domestic magazines]
• A comparative study of the surface and active layer conditions at disturbed forest sites near Yakutsk
  G Iwahana; M Fukuda; Y Kobayashi; T Machimura; AN Fedorov
  PERMAFROST, VOLS 1 AND 2, 483, 488, 2003, [Peer-reviewed], [Lead author], ［Internationally co-authored］, [International Magazine]
  English, International conference proceedings
• Characteristics of Nitrogen cycling in permafrost regional ecosystems in Yakutsk, Russia
  Hatano R; Sawamoto T; Shibuya M; Saito H; Tuno Y; Takahashi K; Kobayashi Y; Iwahana G; Desyatkin RV; Isaev AP
  Proceedings of the ninthe symposium on the joint Siberian permafrost studies between Japan and Russia in 2000, 99, 103, 2001, ［Internationally co-authored］, [International Magazine]
  English, Symposium
• Fire effects on surface fluxes and active layer dynamics in Taiga forest over east Siberian permafrost region. 2. Thermal characteristic changes of active layers induced by forest fire
  IWAHANA G.
  Proc. Ninth Symposium on the Joint Siberian Permafrost Studies between Japan and Russia in 2000, Sapporo, 162, 169, 2001, [Lead author], ［Internationally co-authored］, [International Magazine]
  International conference proceedings

• Weak Layers of Slab Avalanches Occurred in Hokkaido in the Decade from 2007 to 2017 - The investigations of Snow Damage Research Team in Hokkaido Branch of JSSI -
  Ozeki Toshihiro; Sawagaki Takanobu; Shimoyama Kou; Sugiyama Shin; Yamanoi Katsumi; Yamaguchi Satoru; Akitaya Eizi; Arakawa Hayato; Hachikubo Akihiro; Harada Yusuke; Iwahana Go; Kodama Yuji; Nakamura Kazuki; Sakakibara Daiki; Sakakibara Ken-ichi, Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2017, 0, 214, 214, 2017
  The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
• Fabric and Crystallinity of Massive Ground Ice in Permafrost
  Ohno Hiroshi; Iwahana Go; Hori Akira; Miyamoto Atsushi; Iizuka Yoshinori; Hachikubo Akihiro; Minami Hirotsugu; Uchida Masao; Hinzman Larry; Sone Toshio, Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2015, 157, 157, 2015
  The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
• 凍土学の本場リポート : モスクワ大学地質学部地球雪氷学科における在外研究
  岩花 剛, 雪氷, 68, 1, 47, 50, 15 Jan. 2006
  日本雪氷学会, Japanese
• Comparison of the surface balance conditions in different stages after forest disturbance in yakutsk region, Eastern Siberia.
  Proceedings of the tenth symposium on the Joint Siberian Permafrost Studies between Japan and Russia in 2001, 29, 34, 2003

• 北極読本 : 歴史から自然科学、国際関係まで
  南極OB会
  成山堂書店, Nov. 2015, 9784425948413, vi, 176, 14p, 図版 [16] p, Japanese, [Contributor]

• Permafrost hydrology in an Arctic tundra ecosystem: quantifying water sources using stable water isotopes
  Hyejung Jung; Jinho Ahn; Go Iwahana; Jeonghoon Lee
  20 Jan. 2025, Copernicus GmbH
  20 Jan. 2025 - 20 Jan. 2025, Global warming in the Arctic can lead to the alteration of the hydrological cycle and the thawing of permafrost. In this study, we utilized stable water isotope techniques (δ2H and δ18O) to infer the sources mixing of stream water at two sites (HV and PS) along the Sag River on the North Slope, Alaska (USA) during August 2022. The isotopes of snow and rain samples were plotted above the LMWL and reflected the isotopic characteristics of seasonal precipitation in Alaska. The porewater collected within the active layer showed enriched isotope values than other samples, indicating summer precipitation. Using δ18O and deuterium excess in a Bayesian mixing model, we estimated the contribution rates of summer precipitation, seasonal ice, and ice wedge. The results indicated a substantial contribution from melted seasonal ice (HV: 96.8% and PS: 74.1%), formed by frozen precipitation from the previous year, to surface water in August. Additionally, it was observed that the contribution of ice wedge was relatively greater in the downstream (PS: 21.8%) compared to the upstream (HV: 2.1%). Furthermore, we observed that the isotopic compositions of surface water in the PS site revealed evidence of evaporation, as indicated by a characteristic isotopic fractionation slope. Summer precipitation (HV: 1.1% and PS:4.1%) did not contribute substantially to surface waters. This research provides insight into fundamental processes related to sources and mixing of waters in permafrost hydrology.
• Understanding formation of ice wedges and origin of trapped greenhouse gas at Zyryanka, Northeastern Siberia 
  Nayeon Ko; Hansu Park; Hyejung Jung; Go Iwahana; Alexander Fedorov; Jinho Ahn
  27 Mar. 2022, Copernicus {GmbH}
  27 Mar. 2022 - 27 Mar. 2022
• Special profiles of ground temperature above permafrost on the summit of Mt. Fuji
  池田敦; 岩花剛; 福井幸太郎
  雪氷研究大会講演要旨集(Web), 2018
  2018 - 2018
• Outreach program by measurements of frost depth (6)
  Harada Koichiro; Yoshikawa Kenji; Iwahana Go; Stanilovskaya Julia; Yuki Sawada; Sone Toshio
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2017, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
  2017 - 2017
• Assessing and Projecting Greenhouse Gas Release from Dynamic Permafrost Degradation - Integration of in-situ and satellite observations, laboratory analysis, and numerical modeling -
  Saito Kazuyuki; Machiya Hirokazu; Ohno Hiroshi; Yokohata Tokuta; Iwahana Go
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2017, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
  2017 - 2017
• Weak Layers of Slab Avalanches Occurred in Hokkaido in the Decade from 2007 to 2017 - The investigations of Snow Damage Research Team in Hokkaido Branch of JSSI -
  Ozeki Toshihiro; Sawagaki Takanobu; Shimoyama Kou; Sugiyama Shin; Yamanoi Katsumi; Yamaguchi Satoru; Akitaya Eizi; Arakawa Hayato; Hachikubo Akihiro; Harada Yusuke; Iwahana Go; Kodama Yuji; Nakamura Kazuki; Sakakibara Daiki; Sakakibara Ken-ichi
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2017, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
  2017 - 2017
• Fabric and Crystallinity of Massive Ground Ice in Permafrost
  Ohno Hiroshi; Iwahana Go; Hori Akira; Miyamoto Atsushi; Iizuka Yoshinori; Hachikubo Akihiro; Minami Hirotsugu; Uchida Masao; Hinzman Larry; Sone Toshio
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2015, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
  2015 - 2015
• Outreach program by measurements of frost depth (4)
  HARADA Koichiro; YOSHIKAWA Kenji; IWAHANA Go; STANILOVSKAYA Julia; SAWADA Yuki
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2015, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
  2015 - 2015
• セワード半島(アラスカ)における火災後の地下氷融解によるポリゴン状沈下に伴う植生変化
  露崎史朗; 岩花剛
  日本生態学会大会講演要旨(Web), 2014
  2014 - 2014
• Development and Internal Structure of a Palsa along the Denali Highway, Alaska
  Iwahana Go; Uchida Masao; Kondo Miyuki; Yoshikawa Kenji; Hinzman Larry
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2013, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering, Japanese
  2013 - 2013
• 衛星データを用いた永久凍土地帯での火災後の融解深の検出の試み
  原田鉱一郎; 成田憲二; 斉藤和之; 岩花剛; 澤田結基; 福田正己
  雪氷研究大会講演要旨集, 2013
  2013 - 2013
• Changes in the alpine vegetation of Mt. Koizumidake,Taisetsu Mountains,Hokkaido,Japan,detected by the monitoring in permanent plots
  SUKENO Mikio; IWAHANA Go
  Proceedings of the General Meeting of the Association of Japanese Geographers, 2012, The Association of Japanese Geographers
  2012 - 2012, Alpine vegetation is predicted to be particularrly vulnerable to climatic change or global warming. We detected the changes in the alpine vegetation of Mt. Koizumidake, Taisetsu Mountains, Hokkaido, Japan, by the monitoring in permanent plots and the meteorological measurements including a monitoring of thermal and hydrological condition in the ground. The results of monitoring in alpine fellfield suggested that many alpine plants grow thickly in correspondence with the anomalous increase of air temperature and summer precipitation in 2010-2011. Wetland species may expand at the spring in the alpine fellfield, by a becoming wetter condition (ex. Scirpus maximowiczii C.B.Clarke)
• 富士山頂の凍土観測(2010~2012年)
  池田敦; 岩花剛; 福井幸太郎; 末吉哲雄; 斉藤和之; 原田鉱一郎; 澤田結基
  雪氷研究大会講演要旨集, 2012
  2012 - 2012
• Methane flux observed at Taiga-tundra boundary in Eastern Siberia
  Shingubara Ryo; Takano Shinya; Iwahana Go; Trofim Maximov; Sugimoto Atsuko
  Abstracts of Annual Meeting of the Geochemical Society of Japan, 2011, GEOCHEMICAL SOCIETY OF JAPAN
  2011 - 2011, タイガ－ツンドラ境界域に位置する北極圏東シベリアチョクルダ周辺でメタンフラックスを観測した。メタンフラックスは土壌水分、植生に関連して変動し、湿地の窪地で大きな放出が観測された。
• Distribution and characteristics of dissolved organic matter in Indigirka River in Eastern Siberia
  Yamashita Youhei; Takano Shinya; Sugimoto Atsuko; Iwahana Go; Trofim Maximov
  Abstracts of Annual Meeting of the Geochemical Society of Japan, 2011, GEOCHEMICAL SOCIETY OF JAPAN
  2011 - 2011, 北極圏における土壌から河川への溶存有機物流出メカニズムの現状およびその変動に関する知見は極めて限られている。本研究では東シベリアに位置し、比較的流域面積の小さなインディギルカ川における溶存有機物動態の現状の把握およびその将来の変動予測を行う事を目的に、まず始めに、インディギルカ川下流域の溶存有機物濃度・組成の分布パターンを評価した。試料採取は2010年7月にインディギルカ川下流域にて行い、溶存有機炭素（DOC）濃度、紫外可視吸収スペクトルおよび3次元励起蛍光スペクトルの測定を行った。その結果、湿地起源の溶存有機物は他起源のものに比べ、腐植様物質の組成は大きく変わらないものの、タンパク質様蛍光物質の存在割合が大きい事が示唆された。
• Study on stable isotopes of water in permafrost area of Eastern Siberia
  Takano Shinya; Iwahana Go; Sugimoto Atsuko
  Abstracts of Annual Meeting of the Geochemical Society of Japan, 2011, GEOCHEMICAL SOCIETY OF JAPAN
  2011 - 2011, 本研究で対象とした東シベリアはユーラシア大陸北東部に位置する世界最大の永久凍土帯であり、永久凍土は東シベリアの水循環システムの中で重要な役割を担っている。地球温暖化により永久凍土のシステムの撹乱が懸念されているが、それにより水循環や物質循環、植生の変化にまで影響が及ぶ可能性がある。この東シベリアの水循環システムを解明するにあたり、水の安定同位体比は非常に有効なツールである。永久凍土帯での水循環システムや水の安定同位体比を用いた研究は報告されるようになってきたが、東シベリアでの河川水や地下水、永久凍土の安定同位体比の変動を考察した研究例はまだない。そこで本研究では、永久凍土帯から流出する水を通しての水循環の解明を目的とし、河川水や地下水の他に、土壌水や凍土の水(氷)を採取し、その水素・酸素同位体比を測定した。
• Geocryological characteristics of upper permafrost layer in a zone of forest-tundra, near Chokurdakh, Russia
  Iwahana Go; Takano Shinya; Sugimoto Atsuko
  Proceeding of Annual Conference, 2011, THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Japanese
  2011 - 2011, Global climate warming can lead to increase in the active layer thickness in permafrost regions. There is limited information about cryology including geochemical characteristics in the upper permafrost layers which is expected to thaw in case of the climate warming. We studied cryostratigraphy and water stable isotope profiles of the active layers and the upper permafrost layers at five sites near Chokurdakh city, Russia. We found that there are high volumetric ice contents with ice lenses down to around 3m depth. The values of water stable isotopes decreased with depth. And changes of the isotopic values associated with volumetric ice contents were found.
• Monitoring of Permafrost in the Daisetsu Mountains
  Iwahana Go; Ishikawa Mamoru; Sone Toshio; Sawada Yuki; Katamura Fumitaka; Sueyoshi Tetsuo; Harada Koichiroi
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2011, English
  2011 - 2011
• On detection of mountain permafrost boundary using ground-temperature lapse rate
  Tetsuo Sueyoshi; Atsushi Ikeda; G. Iwahana
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2011, English
  2011 - 2011
• 東シベリアカラマツ林土壌における夏期温室効果ガスフラックスの年次変動
  小出隆広; 斎藤秀之; 城田徹央; 岩花剛; MAXIMOV Trofim; 長谷川周一; 波多野隆介
  日本土壌肥料学会講演要旨集, 15 Sep. 2009, Japanese
  15 Sep. 2009 - 15 Sep. 2009
• 富士山の永久凍土観測開始
  池田敦; 岩花剛; 田村亨; 福井幸太郎; 渡邊達也; 北村裕規; 西井稜子
  日本地理学会発表要旨集, 2009
  2009 - 2009
• Evaluation of Temporal-Spatial Heat Distribution at a Permafrost Area of Daisetsu Mountains, Hokkaido
  Takehiro Maeda; Hidenori Arai; Go Iwahana; Mamoru Ishikawa
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2009, English
  2009 - 2009
• Quantifying the water cycle components at a permafrost area of Daisetsu Mountains, Hokkaido
  Hidenori Arai; Takehiro Maeda; Mamoru Ishikawa; Go Iwahana; Atsuko Sugimoto
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2009, English
  2009 - 2009
• A study on unfrozen water content in porous media using the Differential Scanning Calorimetry
  Naoyuki Gocho; Go Iwahana
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2009, English
  2009 - 2009
• Characteristic of icicle formation in the railway tunnels in Hokkaido
  G. Iwahana; Hiroki Suzuki; Naohito Ogawa; Satoshi Akagawa
  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research, 2008, English
  2008 - 2008
• Influence of irrigation on the thermo-hydrological dynamics of sandy active layer in a larch forest near Yakutsk, eastern Siberia
  Iwahana Go; Saito Hideyuki; Shirota Tetsuou; Lopez Larry; Fukuda Masami
  Proceeding of Annual Conference, 2007, THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES, Japanese
  2007 - 2007, 永久凍土帯における森林生態系の土壌水分変化に対する応答特性を把握するために，東シベリア・ヤクーツク近郊に位置する観測サイト（スパスカヤパッド）のカラマツ林において潅水実験を実施している．各10m四方の潅水区（Iサイト）及び対照区（Cサイト）を設定し，2003年の融解期に予備調査を行った後，2004，2005，2006年の融解期にIサイトにおいてそれぞれ合計120，130，100mmの潅水を7月・8月の間に6から13回に分けて行った．本発表では，2003年6月から2006年9月にかけて実施したこの比較実験中の地温及び土壌水分量，地中熱流量の観測結果を述べる．
• 東シベリアカラマツ成熟林における土壌水分が林冠部の光合成能力と葉面積指数に与える影響
  斎藤秀之; 城田徹央; 岩花剛; LOPEZ Larry; マキシモフ TC; 高橋邦秀
  日本森林学会大会学術講演集(CD−ROM), 03 Apr. 2006, Japanese
  03 Apr. 2006 - 03 Apr. 2006
• 東シベリアのカラマツ林における夏季の蒸発散特性
  小林 義和; 町村 尚; 岩花 剛; 福田 正巳; Fedorov A.N.
  水文・水資源学会研究発表会要旨集, 2002, 水文・水資源学会, Japanese
  2002 - 2002

• AMERICAN GEOPHYSICAL UNION
• JAPAN GEOSCIENCE UNION
• THE JAPANESE SOCIETY OF SNOW AND ICE

• 完新世北極温暖期：海陸における気候連鎖とティッピングポイントの検証
  科学研究費助成事業
  Apr. 2025 - Mar. 2029
  内田 昌男; 梶田 展人; 松中 哲也; 岩花 剛; 山田 桂:久保田 好美
  日本学術振興会, 基盤研究(A), 国立研究開発法人国立環境研究所, 25H01187
• Mapping permafrost thawing at fire-scars and onsite observations of their environmental changes
  Grants-in-Aid for Scientific Research
  01 Apr. 2023 - 31 Mar. 2028
  古屋 正人; 石川 守; 岩花 剛; 柳谷 一輝
  永久凍土の融解により凍土中に封じ込められていた炭素(C)が再放出することによって、さらなる温暖化を生み出す可能性がPermafrost Carbon Feedbackとして懸念されているが、その実態は不明な点が多い。地上気温が徐々に上昇することに伴う凍土融解(Gradual thaw)と山火事等による地表擾乱に伴う急で突発的な凍土融解(Abrupt thaw)がありうる中で、前者はモデル予測がしやすいのに対し、後者は文字通りどこで起きるかもわからない。本研究では人工衛星搭載の合成開口レーダー(Synthetic Aperture Radar:SAR)の観測を通じて後者の定量化を目指している。対象領域として、ロシアのサハ共和国バタガイ、米国カナダ国境にあるユーコン準州ビーバークリーク、カナダのノースウェストテリトリでの森林火災跡地での融解沈下をSAR画像を用いた干渉法(Interferometric SAR:InSAR)で検出して、時空間変動を調べた。
  バタガイとビーバークリークにおいては、ALOS-2の高分解能画像(約3m)で調べることによって、現地調査との対応も詳細に調べている。Yanagiya et al (2023)で報告したバタガイの2018年火災跡では、2020年以降の3年間で最大20cmの沈降を検出した。時系列解析の結果によると、晩夏にステップ状に沈降を起こしていることが分かる。ただし、火災後内部での沈降分布は不均一が高い。
  2023年8月にも前年に引き続き、ビーバークリークの2019年火災跡地で現地調査を実施した。620メートルの観測線を設定し、30メートルおきに融解深をメタルプローブで測定した。観測線の南端で気温計、地温計を設置するとともに、隣接する非火災跡地のコントロールサイトでも同様の測定を実施した。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 23K25947
• Mapping permafrost thawing at fire-scars and onsite observations of their environmental changes
  Kakenhi Kiban (B)
  Apr. 2023 - Mar. 2028
  Masato Furuya; Mamoru Ishikawa; Go Iwahana; Kazuki Yanagiya
  JSPS, 基盤研究(B), Hokkaido University, 23H01251
• 氷室・風穴（自然冷熱エネルギー）の機能を地域環境保全へ還元する再エネ利用研究
  科学研究費助成事業
  01 Apr. 2024 - 31 Mar. 2027
  斉藤 和之; 立澤 史郎; 平澤 悠; 澤田 結基; 木村 賢人; 岩花 剛
  日本学術振興会, 基盤研究(B), 国立研究開発法人海洋研究開発機構, 24K03143
• 温暖化による永久凍土中水銀の放出と環境に与える影響
  科学研究費助成事業
  01 Apr. 2023 - 31 Mar. 2026
  永淵 修; 中澤 暦; 篠塚 賢一; 岩花 剛; 末吉 哲雄
  日本学術振興会, 基盤研究(C), 福岡工業大学, 23K04096
• Assessment of influence of water and biogeochemical fluxes on Arctic amplification
  Grants-in-Aid for Scientific Research
  05 Apr. 2021 - 31 Mar. 2025
  朴 昊澤; 田上 雅浩; 檜山 哲哉; 一柳 錦平; 渡邉 英嗣; 岩花 剛; 鈴木 和良
  起源追跡の利点を持つ同位体比の変化に基づいて水循環の変化を評価するために、フェアバンクスとカナダのケンブリッジベイのサイトで土壌水、積雪水、及び河川水の採水を継続した。そこで取得した降水の安定同位体分析を進め，それに加えて地球規模での降水の同位体比の観測網（GNIP）などのデータ，そして同位体再解析データを使って，高緯度域の水蒸気輸送について北大西洋振動（NAO）の影響を評価した。
  降水・地下水の安定同位体比とトリチウム濃度を用い、端成分混合解析によってレナ川の河川水に対する融雪水・暖候期降雨・地下水（または凍土起源水）の寄与を成分分離し、同位体トレーサープロセスを取り込んだ陸域生態系モデルCHANGEの検証に用いた。
  陸域生態系モデルCHANGEが起源分離した河川流出量を海氷海洋結合モデルCOCOの境界条件として与え、北極海における起源水の分布や北極海からの蒸発に対するその寄与を評価した。特にスピンアップ期間の長さなどに対する起源水存在比の不確定性も評価した。また海氷融解水の時空間変動についてもサブ海域ごとに解析した。
  陸域生態系モデルと海氷海洋結合モデルから出力された北極域における蒸発散量や蒸発散に占める起源水の割合を、水同位体大気大循環モデルの境界条件として与えたモデル実験の準備を行った。具体的には、複数の起源水を取り扱えるようにモデルのスキームを高度化し、異なるグリッド格子系を採用しているモデル同士のデータ変換を行った。スキームの高度化において、モデルにいくつかのバグが見つかり、その問題を修正し、北極域の降水変動に対する陸域起源水の影響を定量化した。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Japan Agency for Marine-Earth Science and Technology, 21H04934
• Co-production on permafrost degradation impact assessment for sustainable relationship
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
  01 Apr. 2019 - 31 Mar. 2023
  飯島 慈裕; 高倉 浩樹; 齋藤 仁; 檜山 哲哉; 岩花 剛; 桐村 喬
  2019年度は、当初計画に従い、自然環境調査と人文社会調査で下記の課題を開始した。また、これまで先行的に実施していた本研究に関連する研究活動と構想について国内外での成果発表や意見交換を積極的に行った。年度末に、新型コロナウィルスの影響で海外研究者との打合せや巡検が中止になった影響はあったものの、研究立上げとして初年度は順調に進捗した。
  1. 自然環境調査として、2019年9-10月にかけて、ロシア・サハ共和国のレナ川中流域とバタガイにて、永久凍土荒廃状況の調査を実施した。永久凍土荒廃現象の広域解析に使用するALOS2-PALSAR2のデータの収集・整備を進め、モンゴルでは、永久凍土融解地域の水源枯渇に関連した水サンプルの取得や成分分析に関して現地研究機関の協力で現地調査と解析を実施した。UAVを新規に導入し、近接リモートセンシングによる永久凍土荒廃地形の検出に向けた3次元地形モデルの作成方法に関する検討を開始した。
  2. 人文社会調査として、ロシア、モンゴルの現地研究協力機関と、地理情報データの整備状況に関する打合せと、解析方法に関する検討を開始した。永久凍土の融解が地域社会に及ぼす影響についての既往研究成果をまとめた、超学際的な環境教育教材冊子「永久凍土と文化」を執筆・出版し、11月にロシア・サハ共和国のヤクーツク市とチャラプチャ郡で、研究者向けおよび調査村落での発表会を行った。
  3. 先行して実施していた関連研究成果の公表と普及について、国内外で活動を展開した。JpGU（5月日本）、AGU（12月アメリカ）において、本研究に関連する発表を行ったほか、先述の環境教育教材の出版と11月には現地での普及活動に関するワークショップを開催し、現地研究者やステークホルダーからその重要性に関して認知が進んだ。また、永久凍土地域の気候変動の影響と今後必要な研究課題に関する総説が掲載された。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Mie University, 19H00556
• リモートセンシングと現地観測による永久凍土融解過程と速度の定量化
  科学研究費助成事業 基盤研究(B)
  01 Apr. 2018 - 31 Mar. 2023
  岩花 剛; 内田 昌男; 阿部 隆博
  2019年度は、対象とした永久凍土エリアのうち、東シベリア・マイヤ地区、アラスカ・ノーススロープ、フェアバンクス近郊、大雪山系におけるInSAR解析および現地調査を実施した。
  東シベリアではこれまでの調査地マイヤに加え、新たにバタガイ調査地を追加した。マイヤは居住地全体が高含氷率永久凍土上に存立し、サーモカルストの影響を受ける地域である。バタガイ近郊では、森林火災が最近10年間に頻発し、森林生態系へサーモカルストの影響が危惧される地域である。これらの対象地では地表面変位の時空間的変化をマイクロ波リモートセンシング（InSAR解析）とフィールド測量によって測定し、サーモカルスト沈下と季節的地表面変位の空間分布率の把握を試みた。InSAR解析の結果を検証するために、約35測量点を含む30 x 30mの5つのプロットにおいて2018－2019年の9月下旬から10月初旬に比高測量を実施した。サーモカルスト沈下の進行は、対象地全体の平均値としてInSARでも整合的な結果が得られたが、より詳細な検証には観測の継続と観測点の追加が必要であることが示唆された。これらの研究結果は科学雑誌に投稿し、査読中である（Abe et al., 2020）。2019年9月下旬、バタガイにおいて2014年の火災跡地でフィールド調査(相対高さ、土壌水分、解凍深さ、土壌サンプリング)を実施した。また、2018年、および2019年8月の火災跡地を訪問し、2014年の火災区と同じ調査を行い、今後の変化をモニタリングする予備調査を実施した。これまでのInSAR解析結果は共同研究者A. N. Fedorov氏を通じて地域コミュニティーに提示された。
  この他、アラスカのノーススロープ、フェアバンクス、大雪山系におけるInSAR解析および現地調査も同時に進行中である。
  日本学術振興会, 基盤研究(B), 北海道大学, 18H03353
• Analysis of ecosystem function of taiga in eastern Siberia
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
  2009 - 2012
  SUGIMOTO Atsuko; IRINO Tomohisa; OHOTE Nobuhito; TOKUCHI Naoko; IWAHANA Go; KODAMA Yuuji; YAMASHITA Yohei; ISHII Yoshiyuki; OHOTA Takeshi; UZUKI Rikie; YONENOBU Hitoshi
  Field observations were carried out on water, carbon, and nitrogen cycles in taiga and taiga-tundra boundary in eastern Siberia. Soil moisture water equivalent at taiga forest study site was reconstructed for pas 100 years from tree-ring 13C of larch. Our observational results showed that the wet condition in 2006-2007 was extreme event, and runoff from the region to Lena river was generated for a whole year during this period. N dynamics was also observed in larch forest. Soil inorganic N pool size showed large seasonality depending on the soil temperature.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 21403011
• The actual states of permafrost degradation
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
  2009 - 2011
  ISHIKAWA Mamoru; SAITO Kazuyuki; IWAHANA Go; MATSUOKA Norikazu; SUGIMOTO Atsuko
  This study aims to clarify thermal state of permafrost especially on Mongolia, Svalbard and Japanese high mountains under the umbrella of global permafrost network. In Mongolia we found occurrences of the colder permafrost on the northerner territories and large spatial differences in temperatures even within small areas. We deduced that permafrost warming is strongly controlled by the rate of unfrozen water contents. Recently the international permafrost association has paid special attention of Mongolian permafrost observatories, since number of research borehole has been significantly increased by our study. The deepest, 10m-permafrost-research-borehole among Japan has been installed on the permafrost, Daisetsu Mountains, Hokkaido. The low ground temperature, -2℃ at 10m, indicate the presence of thermally stable permafrost. The modeling schemes were improved especially for soil freezing and thawing processes in the GCM, and have been applied to reconstruct paleo-permafrost distribution. For verification we referred the distribution of fossil periglacial phenomena. The realistic verification needs for deeper understanding of concurrent relation between climate and periglacial processes. In this context we studied concurrent climatic situations for the frost wedge and frost creep, and paleo-permafrost development of pingo.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 21310001
• Changes of palsas and climate in the Daisetsu Mountains, Hokkaido
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
  2009 - 2011
  SONE Toshio; HARADA Koichro; IWAHANA Go; MORI Junko
  Palsas are permafrost mounds which indicate the presence of permafrost geomorphologically. In Japan, they are distributed only in the Daisetsu Mountains. Meteorological, ground temperature and electric resistivity measurements and survey of the distribution of palsas were conducted. The rapid degradation of them was detected in 2010. Permafrost temperatures of palsas were indicated to be near 0℃. Most of them do not seem to be active.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21500993
• Isoscape monitoring of effect of global warming and land use change on water and material cycling-Hokkaido Isotope Map
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
  2009 - 2011
  SUKIMOTO Atsuko; ISHIKAWA Mamoru; IWAHANA Go; MIKAMI Hidetoshi
  Isoscape monitoring network was established, and Hokkaido Isotope map on water and nitrogen was made on river, ground water, and lake water. Precipitation was also observed at monitoring stations. Water isotope map showed spatial distribution of d-excess differs between summer and winter reflection the moisture source of winter precipitation generally in Hokkaido. However, constant and also high d values were observed in rivers south of Shikotsu lake, indicating a large ground water system probably connecting to Shikotsu lake. Nitrate concentration was high in the rivers in farmland. Nitrate d^<15>N showed also wide range but mostly 0 to 8‰. Variation may depend on the difference in source of N.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21510001
• 温暖化と火山活動監視に向けた富士山頂の永久凍土モニタリング
  科学研究費助成事業 挑戦的萌芽研究
  2009 - 2010
  池田 敦; 岩花 剛
  富士山山頂部はその標高ゆえに日本では特異な寒冷環境にあり,現在でも永久凍土(通年0℃以下にある地盤)がまとまって存在できる本州で唯一の場所であると考えられる.しかし,富士山の永久凍土分布は,これまで地表面付近の地温から非常に粗く見積もられていたに過ぎず,その実態はほとんど不明であった.しかし平成20年度に開始した我々の集中的な調査により平成21年度までに,山頂火口周辺の緩斜面において,積雪が吹き払われる地点(風衝地)では夏季の降雨浸透が,積雪が吹きだまる地点(風背地)では積雪による冬季の寒気遮断がそれぞれ地温を高く保っており,永久凍土の発達を阻害していることが明らかにできた.その結果を受けて,山頂部において永久凍土が発達しうるのは,風衝地でなおかっ透水性の悪い(降雨が浸透しにくい)溶結凝灰岩層であると考え,平成22年度にはそのような場所に本研究計画の目標・目的であった深さ約10mの地温観測孔を設置することに成功した.それにより富士山では初となる永久凍土本体の地温モニタリングを開始することができたと見込んでいる.実際に地温より永久凍土が直接観測できたと確定されるのは,2年間以上0℃以下であった記録が取れた時点であるが,掘削時の地温が深部で-3℃前後とかなり低温だったことを考えると,永久凍土の存在はほぼ確実視できる.今後,観測を継続することによって気象要素の変動に対する永久凍土の応答についての正確な情報が得られ,温暖化によって富士山の永久凍土分布が短期間に急激に縮小したという最近マスメディアを賑わせた見解の是非も検証されるであろう.また各要素間の関係を定量化し,より現実的な永久凍土分布を見積もるなど研究を発展させる予定である.
  日本学術振興会, 挑戦的萌芽研究, 信州大学, 21650236
• Study on Influence of Climate Change on Mountain-Top Ground Environment
  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
  2009 - 2010
  IWAHANA Go
  The occurrence of permafrost was confirmed at four observed points in the summit area of Mt. Daisetsu. The extrapolation of the lower part of the ground temperature profile from 10m bore-hole, which installed during this study, indicates the depth of the permafrost base to be 30-40m. I monitored two ground temperature profiles down to 3m on the summit of Mt. Fuji, but I have not confirmed the occurrence of permafrost. Analysis of boring cores from Siberia and Japanese mountain permafrost showed similar characteristics of cryostratigraphy.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 21710028
• Development of Chilled Gas Pipeline Complying with Environmental Change, Innovation due to Composite Materials
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
  2008 - 2010
  KANIE Shunji; AKAGAWA Satoshi; MIKAMI Takashi; IWAHANA Go; SATO Motohiro
  A pipe-in-pipe filled with sand was developed as an innovative structure for chilled gas pipeline in northern cold regions where a plenty of natural gas is reserved. As a result of the study, it is confirmed that the pipe-in-pipe can comply with environmental change due to increased ductility by sand because it allows large deformation. In addition, self recovery in flexural rigidity and anti-leaking becomes possible by artificial freezing and thawing of surrounding soil.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 20360196
• Establishment of the system for the risk evaluation of geohazards at volcanic soil slope in cold regions
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
  2007 - 2009
  MIURA Seiichi; AKAGAWA Satoshi; ISHIKAWA Tatsuya; YOKOHAMA Shoji; KAWAMURA Shima; IWAHANA Go; ITOU Yoshihiko; NISHIMOTO Satoshi
  We elucidated the interaction between various factors which caused subsurface failure of volcanic soil ground subjected to freeze-thaw action in cold regions in terms of soil mechanics, and we proposed a new simple prediction method for the rain-induced slope failure in snow-melting seasons in consideration of the degradation of deformation-strength characteristics of geomaterials due to freeze-thawing. We also developed a geo-information database which integrated the various different kinds of information such as weather reports, geotechnical information, and records for past geohazards. Based on these achievements, finally, we developed the system which could evaluate a risk of rain-induced slope failure at subsurface layers suffered from freeze-thaw by using both above-mentioned prediction method and geo-information database.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 19201035
• 森林破壊が永久凍土の熱的安定性に及ぼす影響に関する研究
  科学研究費助成事業 特別研究員奨励費
  2003 - 2005
  岩花 剛
  最終年度の本年は,これまで蓄えられた観測データを基にした研究成果のまとめを主とした.一方,多くの共同研究者が関わるプロジェクト研究として,今後も観測研究が継続される事となったため,同時進行でこれまでの観測の継続も行った.得られた知見を包括的に統合し,さらに発展させるため今年度の大半はロシア・モスクワ大学の凍土学研究部門に在籍し,研究を進めた.計画2)の森林サイト,伐採地,火災跡地においてのフラックス測定および活動層の観測は,本年度に至り,伐採実験地で森林伐採後5年目,火災跡地では火災後4年目の観測に対応する.
  表面攪乱を受けた実験地では,昨年度に続き表面植生の回復が継続した.このため,地表面における熱・水輸送の特徴も昨年と同様であった.実験伐採地では,昨年度に引き続き地表面が冠水し,その面積も増加した.真夏から終期にかけて非常に大きな降水量が観測されたことが主な原因となり,対象地域全体の凍土融解深が増加したことは,今年度新たに得られた知見である.この年変動による降水量の変化が土壌水分量の変化,ひいては凍土融解深に及ぼす影響を地表面状態の攪乱による影響から分離して評価するための解析的計算を実施中である.
  モスクワ大学地質学部地球雪氷学科での在外研究中には,当初の研究目的を達成するために必要な情報の収集と,すでに得られている観測データを基に研究成果をまとめる議論を,ロシア側の多くの研究者の協力を得て,約1年間行った.観測データの解析結果の発表は,まず,昨年度投稿中であった伐採実験後2年目の対照区と伐採地における活動層エネルギー収支解析および水収支解析の結果を比較したものを公表した.これに続き,地表面のエネルギーバランス観測の解析結果についての論文を準備中である.ロシアでの凍土学の蓄積が予想以上に多く,本研究の目的をより高いレベルで実現するためにはさらに時間を要することは否めない.
  日本学術振興会, 特別研究員奨励費, 北海道大学, 03J09598

• Lecturer for the summer school of the Fukuyama City University
  09 Jul. 2025 - 09 Jul. 2025
  Lecturer
  Fukuyama City University
  the summer school of the Fukuyama City University