Researcher Database

Yoshinori Iizuka
Institute of Low Temperature Science Frontier Ice and Snow Science
Associate Professor

Researcher Profile and Settings

Affiliation

  • Institute of Low Temperature Science Frontier Ice and Snow Science

Job Title

    Associate Professor

URL

Research Areas

  • Environmental science / Environmental dynamic analysis
  • Earth and planetary science / Meteorology/Physical oceanography/Hydrology

Research Activities

Published Papers

MISC

  • Yoshinori Iizuka, Atsushi Miyamoto, Akira Hori, Sumito Matoba, Ryoto Furukawa, Takeshi Saito, Shuji Fujita, Motohiro Hirabayashi, Satoru Yamaguchi, Koji Fujita, Nozomu Takeuchi  Arctic, Antarctic, and Alpine Research  49-  13  -27  2017/02   [Not refereed] [Not invited]  
    © 2017 Regents of the University of Colorado. We examine a firn core from a dome in southeast Greenland that exhibits distinct firn densification. The ice was-20.9 °C at 20 m depth, and the core gives an average accumulation rate of 1.0 m w.e. yr -1 in water equivalent. However, the close-off density of 830 kg m -3 occurs at 83.4-86.8 m depth, which is about 20-m shallower than that obtained from two empirical models. Where the density ρ > 750 kg m -3 , the densification appears faster than that from the empirical models. As a result, compared to the empirical coefficient, the actual compactive viscosity coefficient is nonlinear and decreases at ρ > 750 kg m -3 , indicating that the firn with a higher density is softer than that from the empirical result. We argue here that the high accumulation rate creates a high overburden pressure in a short time. Thus, the relative softness of the firn may arise from (1) there being not enough time to form bonds between grains as strong as those in a lower accumulation-rate area, and similarly, (2) the dislocation density in the firn being relatively high.
  • S. Schüpbach, H. Fischer, M. Bigler, T. Erhardt, G. Gfeller, D. Leuenberger, O. Mini, R. Mulvaney, N. J. Abram, N. J. Abram, L. Fleet, M. M. Frey, E. Thomas, A. Svensson, D. Dahl-Jensen, E. Kettner, H. Kjaer, I. Seierstad, J. P. Steffensen, S. O. Rasmussen, P. Vallelonga, M. Winstrup, A. Wegner, B. Twarloh, K. Wolff, K. Schmidt, K. Goto-Azuma, T. Kuramoto, T. Kuramoto, M. Hirabayashi, J. Uetake, J. Uetake, J. Zheng, J. Bourgeois, D. Fisher, D. Zhiheng, C. Xiao, M. Legrand, A. Spolaor, J. Gabrieli, C. Barbante, J. H. Kang, S. D. Hur, S. B. Hong, H. J. Hwang, S. Hong, M. Hansson, Y. Iizuka, I. Oyabu, R. Muscheler, F. Adolphi, F. Adolphi, O. Maselli, J. McConnell, E. W. Wolff  Nature Communications  9-  2018/12   [Not refereed] [Not invited]  
    © 2018 The Author(s). The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
  • Yuko Motizuki, Hideaki Motoyama, Yoichi Nakai, Keisuke Suzuki, Yoshinori Iizuka, Kazuya Takahashi  Geochemical Journal  51-  293  -298  2017/01   [Not refereed] [Not invited]  
    © Copyright 2017 by The Geochemical Society of Japan. Ice core samples record information about the geological history of the Earth, including past climate changes. Dome Fuji, situated at the highest point of Queen Maud Land, is considered one of the best drilling locations for procuring samples to reconstruct past climates and environments. We present here fundamental data on the concentrations of dissolved ions in shallow samples, between 7.7 m and 65.0 m depth, from the Dome Fuji ice core drilled in 2001. The measured anions were HCOO-, CH3COO-, CH3SO3 -, F-, Cl - , NO2-, NO3-, SO42-, C2O42-, and PO43-, and the cations were Na + , K+, Mg2+, Ca2+, and NH4+. The temporal resolution of the depth profiles of the ion concentrations was less than one year. No significant correlations were observed among the ions except between Na + and Cl - . The ion balance in the core, based on the averaged ion concentrations of the samples, was different to that of sea salt, a result consistent with the findings of previous studies. In several samples, however, synchronous concentration peaks of Na + and Cl - were identified, and the Cl - /Na + ratios of the corresponding samples were close to the sea salt ratio. This observation indicates the possibility that climate conditions were such that precipitation containing sea salt occurred in the Dome Fuji area. The Cl - /Na + ratio of samples that did not exhibit Na + and Cl - peaks in the depth profile differed from that previously reported for the covering snow. This result implies that Cl - , but not Na + , was redistributed after deposition. High concentrations of SO42- in some samples may account for this alteration of Cl - /Na + ratios. To interpret these observations and elucidate the climatic conditions, further studies, such as isotopic analyses of d18O and dD, are required.
  • Sumito Matoba, Masashi Niwano, Tomonori Tanikawa, Yoshinori Iizuka, Tetsuhide Yamasaki, Tetsuhide Yamasaki, Yutaka Kurosaki, Yutaka Kurosaki, Teruo Aoki, Akihiro Hashimoto, Masahiro Hosaka, Shin Sugiyama  Bulletin of Glaciological Research  36-  15  -22  2018/01   [Not refereed] [Not invited]  
    © 2018 Japanese Society of Snow and Ice. During spring 2017, we conducted research expeditions to the SIGMA-A site, which is located on the northwestern Greenland Ice Sheet. We maintained an automated weather station (AWS) to enable continuous meteorological observations. We extended 1.5-m long poles of the AWS and replaced two aerovane sensors, two thermo-hydrometers and an ultrasonic snow gauge. We also drilled an ice core and recovered a core with a total length of 60.06m, conducted stratigraphic observations, and measured the density of the ice core. In addition, we conducted snow-pit observations and snow sampling, measured the specific surface area of snow using near-infrared reflectance, performed sunphotometry observations, and measured the spectral albedo. To schedule research activities in the field camp and helicopter pick-up flights, we received weather forecasts from the Meteorological Research Institute of Japan through the Internet using a satellite phone every day. We took a male dog to the field camp to alert us to approaching animals.
  • Hiroshi Ohno, Hiroshi Ohno, Yoshinori Iizuka, Akira Hori, Atsushi Miyamoto, Motohiro Hirabayashi, Takayuki Miyake, Takayuki Kuramoto, Shuji Fujita, Shuji Fujita, Takahiro Segawa, Takahiro Segawa, Takahiro Segawa, Ryu Uemura, Toshimitsu Sakurai, Toshitaka Suzuki, Hideaki Motoyama, Hideaki Motoyama  Journal of Geophysical Research: Earth Surface  121-  (7)  1230  -1250  2016/07   [Not refereed] [Not invited]  
    ©2016. American Geophysical Union. All Rights Reserved. The deepest ice in inland Antarctica is expected to preserve the oldest ice records and to potentially contain microorganisms. However, little is known about the physicochemical conditions in the deepest part of ice sheets. This study investigates the physicochemical properties of the bottom section (3000–3035 m) of the Dome Fuji inland ice core, which is located immediately above unfrozen bedrock. The ubiquitous presence of air hydrates and the water isotope composition of ice comparable to the upper main ice core show that the bottom ice is meteoric. However, ion concentrations exhibit abnormal drops at the greatest depths (approximately below 3033 m). In the same depth range, microscopic investigations reveal that considerable relocatio n of air hydrates and microinclusions (water-soluble impurities) occurs, suggesting that the observed reduction in ion concentration results from the segregation of inclusions to ice grain boundaries and the subsequent discharge of chemicals through liquid-water veins. Principal component analysis of ion data supports the meteoric-ice hypothesis, suggesting that the bottom ice had similar original chemistry through all depths. Statistical analyses of chemical data suggest that the water-soluble impurities attached to hydrates or dust (water-insoluble), the ice-soluble chemical species (such as chlorine), and solid particles are less affected by this chemical displacement phenomenon. It is also noteworthy that in the bottom ice, impurity chemicals, which are limiting nutrients for ice-dwelling microorganisms, are concentrated largely to ice-hydrate interfaces, where oxygen, another vital matter for aerobic microorganisms, is also enriched.
  • Ryu Uemura, Kosuke Masaka, Kotaro Fukui, Yoshinori Iizuka, Motohiro Hirabayashi, Hideaki Motoyama  Geophysical Research Letters  43-  (11)  5878  -5885  2016/06   [Not refereed] [Not invited]  
    ©2016. The Authors. The sulfur stable isotopic values (δ 34 S) of sulfate aerosols can be used to assess oxidation pathways and contributions from various sources, such as marine biogenic sulfur, volcanoes, and sea salt. However, because of a lack of observations, the spatial distribution of δ 34 S values in Antarctic sulfate aerosols remains unclear. Here we present the first sulfur isotopic values from surface snow samples along a latitudinal transect in eastern Dronning Maud Land, East Antarctica. The δ 34 S values of sulfate showed remarkably uniform values, in the range of 14.8–16.9‰, and no significant decrease toward the inland part of the transect was noted. These results suggest that net isotopic fractionation during long-range transport is insignificant. Thus, the δ 34 S values can be used to infer source contributions. The δ 34 S values suggest that marine biogenic sulfur is the dominant source of sulfate aerosols, with a fractional contribution of 84 ± 16%.
  • Yu Hoshina, Yu Hoshina, Koji Fujita, Yoshinori Iizuka, Hideaki Motoyama, Hideaki Motoyama  Polar Science  10-  (1)  10  -10  2016/03   [Not refereed] [Not invited]  
    © 2015 Elsevier B.V. and NIPR. Major ions, stable oxygen isotopes (δ 18 O), and accumulation rates are analyzed using high temporal resolution data from shallow ice cores and snow pits from East and West Antarctica. Seasonal cycles of major ions and δ 18 O are well preserved at sites with an accumulation rate threshold of > 100 kg m -2 a -1 and calm wind conditions. The seasonal cycle is unclear at sites with high wind speeds, even if the accumulation rate is greater than the threshold. To eliminate the influences of different source regions on major ion and δ 18 O signals in ice cores, we calculate correlation coefficients between annually averaged major ion concentrations and δ 18 O, and then compare these with accumulation rates and other geographical variables such as latitude, elevation, and distance from the coast. We find that accumulation rates are highly correlated with elevation and the 10-m snow temperature, and that major ions and δ 18 O are negatively correlated at low accumulation sites in inland Antarctica. Negative correlations could reflect inconsistent accumulation due to a large inter-annual variability in the accumulation rate. The results show that the relationships between major ions and δ 18 O may not reflect climatic signatures, and could be a result of the unique characteristics of this arid environment.
  • Shuji Fujita, Shuji Fujita, Kumiko Goto-Azuma, Kumiko Goto-Azuma, Motohiro Hirabayashi, Akira Hori, Yoshinori Iizuka, Yuko Motizuki, Hideaki Motoyama, Hideaki Motoyama, Kazuya Takahashi  Journal of Glaciology  62-  (231)  103  -123  2016/02   [Not refereed] [Not invited]  
    © The Author(s) 2016. In order to better understand the densification of polar firn, firn cores from the three sites within ∼10 km of Dome Fuji, Antarctica, were investigated using surrogates of density: dielectric permittivities ε v and ε h at microwave frequencies with electrical fields in the vertical and horizontal planes respectively. Dielectric anisotropy Δε (=ε v - ε h ) was then examined as a surrogate of the anisotropic geometry of firn. We find that layered densification is explained as a result of complex effects of two phenomena that commonly occur at the three sites. Basically, layers with initially smaller density and smaller geometrical anisotropy deform preferentially throughout the densification process due to textural effects. Second, layers having a higher concentration of Cl - ions deform preferentially during a limited period from the near surface depths until smoothing out of layered Cl - ions by diffusion. We hypothesize that Cl - ions dissociated from sea salts soften firn due to modulation of dislocation movement. Moreover, firn differs markedly across the three sites in terms of strength of geometrical anisotropy, mean rate of densification and density fluctuation. We hypothesize that these differences are caused by textural effects resulting from differences in depositional conditions within various spatial scales.
  • Yoshinori Iizuka, Hiroshi Ohno, Ryu Uemura, Toshitaka Suzuki, Ikumi Oyabu, Yu Hoshina, Kotaro Fukui, Motohiro Hirabayashi, Hideaki Motoyama, Hideaki Motoyama  Tellus, Series B: Chemical and Physical Meteorology  68-  2016/01   [Not refereed] [Not invited]  
    © 2016 Y. Iizuka et al. To better understand how sea salt reacts in surface snow of Antarctica, we collected and identified non-volatile particles in surface snow along a traverse in East Antarctica. Samples were obtained during summer 2012/2013 from coastal to inland regions within 69°S to 80°S and 39°E to 45°E, a total distance exceeding 800 km. The spatial resolution of samples is about one sample per latitude between 1500 and 3800m altitude. Here, we obtain the atomic ratios of Na, S and Cl, and calculate the masses of sodium sulphate and sodium chloride. The results show that, even in the coast snow sample (698S), sea salt is highly modified by acid (HNO 3 or H 2 SO 4 ). The fraction of sea salt that reacts with acid increases in the region from 70°S to 74°S below 3000m a.s.l., where some NaCl remains. At the higher altitudes (above 3300m a.s.l.) in the inland region (74°S to 80°S), the reaction uses almost all of the available NaCl.
  • Yoshinori Iizuka, Sumito Matoba, Tetsuhide Yamasaki, Ikumi Oyabu, Moe Kadota, Moe Kadota, Teruo Aoki  Bulletin of Glaciological Research  34-  10  -10  2016/01   [Not refereed] [Not invited]  
    © Japanese Society of Snow and Ice. In order to understand 1) temporal variations of anthropogenic aerosols from European regions under the Icelandic low with high time resolution, and 2) the snow densification mechanism at the high accumulation dome in Greenland, we drilled a 90.45m ice core in a high accumulation area of the southeastern Greenland Ice Sheet. The drilling site (SE-Dome; 67.18°N, 36.37°W, 3170m a.s.l.) is located 185km north of the town of Tasiilaq in southeastern Greenland. We also conducted borehole temperature measurements. The temperature in the borehole was -20.9°C at a depth of 20m. In addition, we did snow-pit observations, aerosol sampling, snow sampling for chemical and physical analyses and meteorological observation. Air temperature and air pressure were on average -16.8°C and 667hPa during our stay. The aerosol concentration in the top surface 0.1m snow at SE-Dome in the spring of 2015 was lower than those of the other regions in Greenland, likely due to a highland dome of the ice sheet and/or dilution of mass flux by high snow accumulation.
  • Ikumi Oyabu, Ikumi Oyabu, Ikumi Oyabu, Yoshinori Iizuka, Hubertus Fischer, Simon Schüpbach, Gideon Gfeller, Anders Svensson, Manabu Fukui, Jørgen Peder Steffensen, Margareta Hansson  Journal of Geophysical Research  120-  (18)  9789  -9813  2015/01   [Not refereed] [Not invited]  
    © 2015. American Geophysical Union. All Rights Reserved. This study reports the chemical composition of particles present along Greenland’s North Greenland Eemian Ice Drilling (NEEM) ice core, back to 110,000 years before present. Insoluble and soluble particles larger than 0.45 µm were extracted from the ice core by ice sublimation, and their chemical composition was analyzed using scanning electron microscope and energy dispersive X-ray spectroscopy and micro-Raman spectroscopy. We show that the dominant insoluble components are silicates, whereas NaCl, Na 2 SO 4 , CaSO 4 , and CaCO 3 represent major soluble salts. For the first time, particles of CaMg(CO 3 ) 2 and Ca(NO 3 ) 2 •4H 2 O are identified in a Greenland ice core. The chemical speciation of salts varies with past climatic conditions. Whereas the fraction of Na salts (NaCl + Na 2 SO 4 ) exceeds that of Ca salts (CaSO 4 + CaCO 3 ) during the Holocene (0.6-11.7 kyr B.P.), the two fractions are similar during the Bølling-Allerød period (12.9-14.6 kyr B.P.). During cold climate such as over the Younger Dryas (12.0-12.6 kyr B.P.) and the Last Glacial Maximum (15.0-26.9 kyr B.P.), the fraction of Ca salts exceeds that of Na salts, showing that the most abundant ion generally controls the salt budget in each period. High-resolution analyses reveal changing particle compositions: those in Holocene ice show seasonal changes, and those in LGM ice show a difference between cloudy bands and clear layers, which again can be largely explained by the availability of ionic components in the atmospheric aerosol body of air masses reaching Greenland.
  • Ikumi Oyabu, Ikumi Oyabu, Yoshinori Iizuka, Ryu Uemura, Takayuki Miyake, Motohiro Hirabayashi, Hideaki Motoyama, Toshimitsu Sakurai, Toshimitsu Sakurai, Toshimitsu Sakurai, Toshitaka Suzuki, Takeo Hondoh  Journal of Geophysical Research  119-  (24)  45  -14  2014/12   [Not refereed] [Not invited]  
    © 2014. American Geophysical Union. All Rights Reserved. The flux and chemical composition of aerosols impact the climate. Antarctic ice cores preserve the record of past atmospheric aerosols, providing useful information about past atmospheric environments. However, few studies have directly measured the chemical composition of aerosol particles preserved in ice cores. Here we present the chemical compositions of sulfate and chloride salts from aerosol particles in the Dome Fuji ice core. The analysis method involves ice sublimation, and the period covers the last termination, 25.0–11.0 thousand years before present (kyr B.P.), with a 350 year resolution. The major components of the soluble particles are CaSO 4 , Na 2 SO 4 , and NaCl. The dominant sulfate salt changes at 16.8 kyr B.P. from CaSO 4 , a glacial type, to Na 2 SO 4 , an interglacial type. The sulfate salt flux (CaSO 4 plus Na 2 SO 4 ) inversely correlates with δ 18 O in Dome Fuji over millennial timescales. This correlation is consistent with the idea that sulfate salt aerosols contributed to the last deglacial warming of inland Antarctica by reducing the aerosol indirect effect. Between 16.3 and 11.0 kyr B.P., the presence of NaCl suggests that winter atmospheric aerosols are preserved. A high NaCl/Na 2 SO 4 fraction between 12.3 and 11.0 kyr B.P. indicates that the contribution from the transport of winter atmospheric aerosols increased during this period.
  • Ikumi Oyabu, Ikumi Oyabu, Yoshinori Iizuka, Ryu Uemura, Takayuki Miyake, Motohiro Hirabayashi, Hideaki Motoyama, Toshimitsu Sakurai, Toshimitsu Sakurai, Toshimitsu Sakurai, Toshitaka Suzuki, Takeo Hondoh  Journal of Geophysical Research  119-  (24)  45  -14  2014/11   [Not refereed] [Not invited]  
    © 2014. American Geophysical Union. All Rights Reserved. The flux and chemical composition of aerosols impact the climate. Antarctic ice cores preserve the record of past atmospheric aerosols, providing useful information about past atmospheric environments. However, few studies have directly measured the chemical composition of aerosol particles preserved in ice cores. Here we present the chemical compositions of sulfate and chloride salts from aerosol particles in the Dome Fuji ice core. The analysis method involves ice sublimation, and the period covers the last termination, 25.0–11.0 thousand years before present (kyr B.P.), with a 350 year resolution. The major components of the soluble particles are CaSO 4 , Na 2 SO 4 , and NaCl. The dominant sulfate salt changes at 16.8 kyr B.P. from CaSO 4 , a glacial type, to Na 2 SO 4 , an interglacial type. The sulfate salt flux (CaSO 4 plus Na 2 SO 4 ) inversely correlates with δ 18 O in Dome Fuji over millennial timescales. This correlation is consistent with the idea that sulfate salt aerosols contributed to the last deglacial warming of inland Antarctica by reducing the aerosol indirect effect. Between 16.3 and 11.0 kyr B.P., the presence of NaCl suggests that winter atmospheric aerosols are preserved. A high NaCl/Na 2 SO 4 fraction between 12.3 and 11.0 kyr B.P. indicates that the contribution from the transport of winter atmospheric aerosols increased during this period.
  • Shuji Fujita, Shuji Fujita, Kotaro Fukui, Fumio Nakazawa, Hiroyuki Enomoto, Hiroyuki Enomoto, Hiroyuki Enomoto, Shin Sugiyama, Yoshiyuki Fujii, Koji Fujita, Teruo Furukawa, Teruo Furukawa, Keiichiro Hara, Yu Hoshina, Makoto Igarashi, Yoshinori Iizuka, Satoshi Imura, Satoshi Imura, Hideaki Motoyama, Hideaki Motoyama, Sylviane Surdyk, Ryu Uemura  Antarctic Record  58-  352  -392  2014/11   [Not refereed] [Not invited]  
    © 2014 National Institute of Polar Research. In the seventh five-year plan of the Japanese Antarctic Research Expedition, a group of Japanese scientists (led by the National Institute of Polar Research) together with a group of Swedish scientists, conducted field surveys to better understand the glaciology of the ice sheet in Dronning Maud Land, East Antarctica, during the 2007/2008 austral summer season. This paper reports on the planning and field preparations, and outlines the scientific achievements of the field expedition. We have gained numerous new scientific insights on the spatio-temporal distribution of the ice sheet environment in the inland plateau. Here, we provide an overview of the new knowledge gained.
  • Hiroshi Ohno, Hiroshi Ohno, Yoshinori Iizuka, Shinichiro Horikawa, Shinichiro Horikawa, Toshimitsu Sakurai, Toshimitsu Sakurai, Takeo Hondoh, Hideaki Motoyama  Polar Science  8-  (1)  1  -9  2014/03   [Not refereed] [Not invited]  
    Water-soluble trace constituents affect the physicochemical properties of polar ice. Their structural distribution provides important insights into the formation history of ice and inclusions. We report the first finding of KAl(SO 4 ) 2 ·12H 2 O (potassium alum) and Al 2 (SO 4 ) 3 ·nH 2 O (aluminum sulfate) micro-inclusions in the Dome Fuji ice core, East Antartica, using a micro-Raman technique. Eutectic temperatures of these water-soluble species determined using thermal analysis were -0.4°C for potassium alum and -8.0°C for aluminum sulfate. Although the formation process of the aluminum-bearing sulfates remains unclear, the occurrence of these salts largely depends on ice depth. © 2013 Elsevier B.V. and NIPR.
  • Yu Hoshina, Koji Fujita, Fumio Nakazawa, Yoshinori Iizuka, Takayuki Miyake, Motohiro Hirabayashi, Takayuki Kuramoto, Takayuki Kuramoto, Shuji Fujita, Hideaki Motoyama  Journal of Geophysical Research  119-  (1)  274  -283  2014/01   [Not refereed] [Not invited]  
    © 2013. The Authors. Postdepositional changes in water stable isotopes in polar firn were investigated at three sites characterized by different accumulation rates along the East Antarctic ice divide near Dome Fuji. Water stable isotopes, major ion concentrations, and tritium contents of three 2–4 m deep pits were measured at high resolution (2 cm). Temporally, the snow pits cover the past 50 years with snow accumulation rates in the range of 29–41 kg m 2 a 1 around Dome Fuji. Oxygen isotopic profiles in the three pits do not show annual fluctuations, but instead exhibit multiyear cycles. These multiyear cycles are lower in frequency at Dome Fuji as compared with the other two sites. Peaks of water stable isotopes in the multiyear cycles correspond to some ion concentration minima in the pits, although such relationships are not observed in coastal regions. We propose that the extremely low accumulation environment keeps the snow layer at the near surface, which result in postdepositional modifications of isotopic signals by processes such as ventilation and vapor condensation-sublimation. We estimate that oxygen isotopic ratios could be modified by > 10‰ and that the original seasonal cycle could be completely overprinted under the accumulation conditions at Dome Fuji. Moreover, stake measurements at Dome Fuji suggest that the large variability in snow accumulation rate is the cause of the multiyear cycles.
  • Yoshinori Iizuka, Barbara Delmonte, Ikumi Oyabu, Torbjörn Karlin, Valter Maggi, Samuel Albani, Manabu Fukui, Takeo Hondoh, Margareta Hansson  Tellus, Series B: Chemical and Physical Meteorology  65-  (1)  1  -9  2013/08   [Not refereed] [Not invited]  
    Antarctic ice cores preserve the record of past aerosols, an important proxy of past atmospheric chemistry. Here we present the aerosol compositions of sulphate and chloride particles in the Talos Dome (TD) ice core from the Holocene and Last Glacial Period. We find that the main salt types of both periods are NaCl,Na 2 SO 4 and CaSO 4 , indicating that TD ice contains relatively abundant sea salt (NaCl) from marine primary particles. By evaluating the molar ratio of NaCl toNa 2 SO 4 , we show that about half of the sea salt does not undergo sulphatisation during late Holocene. Compared to in inland Antarctica, the lower sulphatisation rate at TD is probably due to relatively little contact between sea salt and sulphuric acid. This low contact rate can be related to a reduced time of reaction for marine-sourced aerosol before reaching TD and/or to a reduced post-depositional effect from the higher accumulation rate at TD. Many sulphate and chloride salts are adhered to silicate minerals. The ratio of sulphate-adhered mineral to particle mass and the corresponding ratio of chloride-adhered mineral both increase with increasing dust concentration. Also, the TD ice appears to contain Ca(NO 3 ) 2 or CaCO 3 particles, thus differing from aerosol compositions in inland Antarctica, and indicating the proximity of peripheral regions to marine aerosols. © 2013 Y. Iizuka et al.
  • Yoshinori Iizuka, Ryu Uemura, Hideaki Motoyama, Toshitaka Suzuki, Takayuki Miyake, Takayuki Miyake, Motohiro Hirabayashi, Takeo Hondoh  Nature  490-  (7418)  81  -84  2012/10   [Not refereed] [Not invited]  
    Sulphate aerosols, particularly micrometre-sized particles of sulphate salt and sulphate-adhered dust, can act as cloud condensation nuclei, leading to increased solar scattering that cools Earth's climate. Evidence for such a coupling may lie in the sulphate record from polar ice cores, but previous analyses of melted ice-core samples have provided only sulphate ion concentrations, which may be due to sulphuric acid. Here we present profiles of sulphate salt and sulphate-adhered dust fluxes over the past 300,000 years from the Dome Fuji ice core in inland Antarctica. Our results show a nearly constant flux of sulphate-adhered dust through glacial and interglacial periods despite the large increases in total dust flux during glacial maxima. The sulphate salt flux, however, correlates inversely with temperature, suggesting a climatic coupling between particulate sulphur and temperature. For example, the total sulphate salt flux during the Last Glacial Maximum averages 5.78â €‰mgâ €‰m -2 â €‰yr -1, which is almost twice the Holocene value. Although it is based on a modern analogue with considerable uncertainties when applied to the ice-core record, this analysis indicates that the glacial-to-interglacial decrease in sulphate would lessen the aerosol indirect effects on cloud lifetime and albedo, leading to an Antarctic warming of 0.1 to 5â €‰kelvin. © 2012 Macmillan Publishers Limited. All rights reserved.
  • D. Dahl-Jensen, M. R. Albert, A. Aldahan, N. Azuma, D. Balslev-Clausen, M. Baumgartner, A. M. Berggren, M. Bigler, T. Binder, T. Blunier, J. C. Bourgeois, E. J. Brook, S. L. Buchardt, C. Buizert, E. Capron, J. Chappellaz, J. Chung, H. B. Clausen, I. Cvijanovic, S. M. Davies, P. Ditlevsen, O. Eicher, H. Fischer, D. A. Fisher, L. G. Fleet, G. Gfeller, V. Gkinis, S. Gogineni, K. Goto-Azuma, A. Grinsted, H. Gudlaugsdottir, M. Guillevic, S. B. Hansen, M. Hansson, M. Hirabayashi, S. Hong, S. D. Hur, P. Huybrechts, C. S. Hvidberg, Y. Iizuka, T. Jenk, S. J. Johnsen, T. R. Jones, J. Jouzel, N. B. Karlsson, K. Kawamura, K. Keegan, E. Kettner, S. Kipfstuhl, H. A. Kjær, M. Koutnik, T. Kuramoto, P. Köhler, T. Laepple, A. Landais, P. L. Langen, L. B. Larsen, D. Leuenberger, M. Leuenberger, C. Leuschen, J. Li, V. Lipenkov, P. Martinerie, O. J. Maselli, V. Masson-Delmotte, J. R. McConnell, H. Miller, O. Mini, A. Miyamoto, M. Montagnat-Rentier, R. Mulvaney, R. Muscheler, A. J. Orsi, J. Paden, C. Panton, F. Pattyn, J. R. Petit, K. Pol, T. Popp, G. Possnert, F. Prié, M. Prokopiou, A. Quiquet, S. O. Rasmussen, D. Raynaud, J. Ren, C. Reutenauer, C. Ritz, T. Röckmann, J. L. Rosen, M. Rubino, O. Rybak, D. Samyn, C. J. Sapart, A. Schilt, A. M.Z. Schmidt, J. Schwander, S. Schüpbach, I. Seierstad, J. P. Severinghaus  Nature  493-  489  -494  2013/01   [Not refereed] [Not invited]  
    Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 ± 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future. © 2013 Macmillan Publishers Limited. All rights reserved.
  • Hideaki Motoyama, Kunio Shinbori, Yoshinori Iizuka, Sumito Matoba, Takayuki Kuramoto, Motohiro Hirabayashi, Takayuki Miyake  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2011-  22  2011/01   [Not refereed] [Not invited]
  • Shuji Fujita, P. Holmlund, I. Andersson, I. Brown, H. I. Enomoto, Y. Fujii, K. Fujita, K. Fukui, T. Furukawa, M. Hansson, K. Hara, Y. Hoshina, M. Igarashi, Y. Iizuka, S. Imura, S. Ingvander, T. Kameda, T. Karlin, H. Motoyama, F. Nakazawa, H. Oerter, L. Sjöberg, S. Sugiyama, S. Surdyk, J. Ström, R. Uemura, F. Wilhelms  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2011-  162  2011/01   [Not refereed] [Not invited]  
    To form a clearer understanding of the spatio-temporal variability of the glaciological environment in Dronning Maud Land (DML), East Antarctica, glaciological investigations were carried out along the 2800-km-long Japanese-Swedish IPY 2007/2008 traverse. The traverse route covers ice sheet ridges and two deep ice coring sites at Dome Fuji and EPICA DML. The surface mass balance (SMB) distribution was derived based on analysis of isochrones within snow pit samples, fim core samples and subsurface radar signals. The SMB averaged over various time scales in the Holocene was determined. This was then compared with various data such as surface elevation, surface slope, prevailing windfield, ice thickness, polarization ratio of satellite-based microwave emissivity and normal backscattered strength of VHF radio waves from within the ice. We find that the large-scale distribution of the SMB depends on the surface elevation, continentality and interactions between ice sheet ridges and the prevailing counterclockwise windfield in DML. A different SMB is found for the windward and leeward sides of the ridges. Local-scale variability in the SMB is essentially governed by bedrock topography which determines the local surface topography and the probability of snow deposition. In the eastern part of DML, the accumulation rate in the second half of the 20 th century is found to be higher by ~15% compared to averages over longer periods of 722 a or 7.9 ka before AD 2008. A similar trend has been reported for many inland plateau sites in East Antarctica. © 2011, The Japanese Society of Snow and Ice / Japan Society for Snow Engineering. All rights reserved.
  • Yoshinori Iizuka, Akira Tsuchimoto, Yu Hoshina, Toshimitsu Sakurai, Margareta Hansson, Torbjörn Karlin, Koji Fujita, Fumio Nakazawa, Hideaki Motoyama, Shuji Fujita  Journal of Geophysical Research Atmospheres  117-  2012/01   [Not refereed] [Not invited]  
    Most of the aerosol particles present in the surface snow and ice of inland Antarctica come from primary sea salt (sodium chloride) and marine biological activity (methansulfonic and sulfuric acids). Melted water from surface snow, firn, and Holocene ice contains mainly sodium, chloride, and sulfate ions. Although it is well known that sea salt aerosols react rapidly with sulfuric acid, a process known as sulfatization, it is not known when this process takes place. In this research we undertake to measure the proportion of sea salt aerosols that undergo sulfatization in the atmosphere and surface snow, as opposed to deeper ice, in order to understand the suitability of sea salt aerosols as a proxy for past climates in deep ice cores. We directly measure the sulfatization rates in recently fallen snow (0-4 m in depth) collected at the Dome Fuji station, using X-ray dispersion spectroscopy to determine the constituent elements of soluble particles and computing the molar ratios of sodium chloride and sodium sulfate. We estimate that about 90% of the initial sea salt aerosols sulfatize as they are taken up by precipitation over Dome Fuji or in the snowpack within one year after being deposited on the ice sheet. Copyright © 2012 by the American Geophysical Union.
  • Y. Hoshina, Koji Fujita, Fumio Nakazawa, Motohiro Hirabayashi, Takayuki Kuramoto, Hideaki Motoyama, Shuji Fujita, Yoshinori Iizuka, Takayuki Miyake  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2011-  161  2011/01   [Not refereed] [Not invited]
  • S. Fujita, P. Holmlund, I. Andersson, I. Brown, H. Enomoto, H. Enomoto, Y. Fujii, K. Fujita, K. Fukui, K. Fukui, T. Furukawa, M. Hansson, K. Hara, Y. Hoshina, M. Igarashi, Y. Iizuka, S. Imura, S. Ingvander, T. Karlin, H. Motoyama, F. Nakazawa, H. Oerter, L. E. Sjöberg, S. Sugiyama, S. Surdyk, J. Ström, R. Uemura, F. Wilhelms  Cryosphere  5-  1057  -1081  2011/12   [Not refereed] [Not invited]  
    To better understand the spatio-temporal variability of the glaciological environment in Dronning Maud Land (DML), East Antarctica, a 2800-km-long Japanese-Swedish traverse was carried out. The route includes ice divides between two ice-coring sites at Dome Fuji and EPICA DML. We determined the surface mass balance (SMB) averaged over various time scales in the late Holocene based on studies of snow pits and firn cores, in addition to radar data. We find that the large-scale distribution of the SMB depends on the surface elevation and continentality, and that the SMB differs between the windward and leeward sides of ice divides for strong-wind events. We suggest that the SMB is highly influenced by interactions between the large-scale surface topography of ice divides and the wind field of strong-wind events that are often associated with high-precipitation events. Local variations in the SMB are governed by the local surface topography, which is influenced by the bedrock topography. In the eastern part of DML, the accumulation rate in the second half of the 20th century is found to be higher by ∼15 % than averages over longer periods of 722 a or 7.9 ka before AD 2008. A similar increasing trend has been reported for many inland plateau sites in Antarctica with the exception of several sites on the leeward side of the ice divides. © Author(s) 2011.
  • Hirokazu Imai, Toshitaka Suzuki, Yoshinori Iizuka, Hideaki Motoyama, Yoshiyuki Fujii  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2011-  208  2011/01   [Not refereed] [Not invited]
  • T. Sakurai, A. Miyamoto, Y. Iizuka, T. Hondoh, T. Uchida, S. Fujita  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2010-  109  2010/01   [Not refereed] [Not invited]
  • Katsunari Matsushima, Toshitaka Suzuki, Hironori Sato, Yoshinori Iizuka, Motohiro Hirabayashi, Hideaki Motoyama, Yoshiyuki Fujii  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2010-  98  2010/01   [Not refereed] [Not invited]
  • Hirokazu Imai, Saeko Yui, Toshitaka Suzuki, Yoshinori Iizuka, Hideaki Motoyama, Yoshiyuki Fujii  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2010-  97  2010/01   [Not refereed] [Not invited]
  • Kumiko Goto-Azuma, Jun Uetake, Kenji Kawamura, Hiroshi Kanda, Takayuki Kuramoto, Takuro Kobashi, Takahiro Segawa, Chiikako Takamura, Motohiro Hirabayashi, Yoshiyuki Fujii, Shuji Fujita, Takayuki Miyake, Hideaki Motoyama, Shuji Aoki, Takakiyo Nakazawa, Nobuhiko Azuma, Motoyuki Sato, Yoshinori Iizuka, Atsushi Miyamoto, Kimikazu Sasa, Akira Hori, Kazuho Horiuchi  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2010-  4  2010/01   [Not refereed] [Not invited]
  • Yu Hoshina, Koji Fujita, Fumio Nakazawa, Takayuki Miyake, Motohiro Hirabayashi, Takayuki Kuramoto, Hideaki Motoyama, Yoshinori Iizuka  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2010-  146  2010/01   [Not refereed] [Not invited]
  • Takayuki Miyake, Yoshiyuki Fujii, Motohiro Hirabayashi, Ryu Uemura, Takayuki Kuramoto, Kumiko Goto-Azuma, Hideaki Motoyama, Makoto Igarashi, Mika Kohno, Ryu Uemura, Koji Fujita, Shinichiro Horikawa, Yoshinori Iizuka, Mika Kohno, Keisuke Suzuki, Toshitaka Suzuki  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2010-  144  2010/01   [Not refereed] [Not invited]
  • Hideaki Motoyama, Takayuki Miyake, Motohiro Hirabayashi, Takayuki Kuramoto, Kumiko Goto-Azuma, Shuji Fujita, Ryu Uemura, Hideaki Motoyama, Kumiko Goto-Azuma, Takayuki Kuramoto, Ryu Uemura, Yoshinori Iizuka, Keisuke Suzuki  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2009-  24  2009/01   [Not refereed] [Not invited]
  • T. Sakurai, Y. Iizuka, S. Horikawa, T. Hondoh, T. Uchida  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2008-  79  2008/01   [Not refereed] [Not invited]
  • Takayuki Miyake, Ryu Uemura, Ryu Uemura, Yoshiyuki Fujii, Yoshinori Iizuka, Takeo Hondoh, Kiyofumi Sano, Takuya Tatenuma  Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research  2008-  77  2008/01   [Not refereed] [Not invited]
  • Yoshinori Iizuka, Morimasa Takata, Takeo Hondoh, Yoshiyuki Fujii  Annals of Glaciology  39-  452  -456  2004/12   [Not refereed] [Not invited]  
    We measured the depth profiles of soluble ions in the Dome Fuji (Antarctica) ice core to search for possible paleoclimate indications of seasonal climate variations in the last glacial period. A 523 mm long core section between 587.65 and 588.18 m depth was selected for this pilot study, and the high-resolution chemical analysis was done on 2 mm thick samples. Our results indicate that anion-cation trapping in ice affects the profiles of the soluble ions and [Na + ] in the core may preserve its seasonal signal. Correlation coefficients and the equivalent balances of the soluble ions suggest the following selective coexistences: (1) [Cl - ] = [Na + ], (2) [NO 3 - ] = 1/2[Ca 2+ ] + [K + ], and (3) [SO 4 2- ] = 1/2[Ca 2+ ] + [H + ] + [Mg 2+ ]. These coexistences are probably due to (1) a sea-salt source of Na + and Cl - , (2) reaction of NO 3 - with dust for Ca 2+ and NO 3 - , and (3) anion-cation trapping in ice for SO 4 2- and Ca 2+ (Mg 2+ ), respectively.
  • Yoshinori Iizuka, Yoshiyuki Fujii, Naohiko Hirasawa, Toshitaka Suzuki, Hideaki Motoyama, Teruo Furukawa, Takeo Hondoh  Journal of Geophysical Research D: Atmospheres  109-  2004/02   [Not refereed] [Not invited]  
    By chemically analyzing snow samples at Dome Fuji, Antarctica, we found that the snowdrift deposited just after snowfall and the snow layer down to 3.4 m have summer minima in the non-sea-salt (nss -SO 2- 4 and Na + concentrations and summer maxima of Cl - /Na + . Such a summer nss-SO 2- 4 minimum in either snowdrift or the snow layer has not been reported at any other site in Antarctica and arises in spite of the known maximum in the nss-SO 2- 4 concentration in aerosol at Dome Fuji in summer. We then did laboratory experiments to better understand the phenomenon. The results supported the following mechanism for the summer nss-SO 2- 4 minimum in the snowdrift and snow layer. In summer, water vapor sublimates from within the snow in the daytime and condenses on the surface as frost in the nighttime, resulting in a dilution of the nss-SO 2- 4 concentration. This sublimation-condensation process likely occurs at other cold inland regions. In addition, the results might be useful for obtaining a high-resolution dating method for Dome Fuji deep ice cores by counting the number of layers with low nss-SO 2- 4 concentration. Copyright 2004 by the American Geophysical Union.
  • Morimasa Takata, Yoshinori Iizuka, Hitoshi Shoji, Atsushi Miyamoto, Sepp Kipfstuhl, Takeo Hondoh, Shuji Fujita, Yoshiyuki Fujii  Antarctic Record  47-  328  -337  2003/11   [Not refereed] [Not invited]  
    An optical scanner for stratigraphical study was developed for the Dome Fuji ice core project II. The optical scanner measures two-dimensional light scattering intensities and records optical structures of ice cores. We developed the scanner hardware and control software. The line scanner is controlled by a personal computer and is constructed for automatic measurement. The sliding speed of the scanner is about 5 mm per second and, therefore, one ice core sample with a standard length for our sample processes (1.5 m long) can be measured within about six minutes. The line scanner was transported to Dome Fuji Station, Antarctica, by the wintering party of the 44th Japanese Antarctic Research Expedition (JARE-44), and will be used for Dome Fuji II ice core measurement by the JARE-45 summer party and successive parties. © 2003 National Institute of Polar Research.
  • Y. Iizuka, H. Satake, T. Shiraiwa, R. Naruse  Journal of Glaciology  47-  223  -231  2001/12   [Not refereed] [Not invited]  
    Debris-laden basal ice is exposed along an ice cliff near Hamna Glacier, Sôya Coast, East Antarctica. The basal ice is about 6.8 m thick and shows conspicuous stratigraphic features. The upper 5.5 m consists of alternating layers of bubble-free and bubbly ice. δ values of the bubble-free ice layers are enriched by 2.4 ± 1.0‰ (standard deviation) for δ 18 O compared to values of neighboring bubbly ice layers above, and slopes of δ 18 O vs δD are close to 8. Such layers are suggested to have been formed by refreezing of meltwater in an open system. In contrast, part of the bubbly ice layers shows neutral profiles for stable isotopes, suggesting that these ice masses are undisturbed ice-sheet ice which was not affected by melting and freezing. The massive alternating layers are thus considered to have been formed by folding of refrozen and non-melted layers. The lower 1.3 m consists predominantly of bubble-free massive ice. The profile of co-isotopic values shows a change of about 3.0‰ for δ 18 O at the interface between bubble-free and bubbly ice. Since the isotopic change occurred over a wider thickness than the upper 5.5 m, the basal ice is suggested to have been formed by refreezing of meltwater on a larger scale than the upper 5.5 m.
  • Yoshinori Iizuka, Makoto Igarashi, Kokichi Kamiyama, Hideaki Motoyama, Okitsugu Watanabe  Journal of Glaciology  48-  452  -460  2002/12   [Not refereed] [Not invited]  
    Snowpack and ice-core samples were collected from the dome of Austfonna ice cap, Svalbard, in the spring of both 1998 and 1999. The samples were analyzed for anions, cations, pH, liquid electrical conductivity and oxygen isotopes. Concentrations of chemical components in snowpack with a history of melting were much lower than those in unmelted snowpack. There was a clear difference between Mg2+/Na+ratios previously in melted snowpack (0.03 ± 0.02) and in unmelted snowpack (0.11 ± 0.02). We propose that the Mg2+/Na+ratio can be used as an indicator of whether or not firn or bubbly ice in the Austfonna ice core has experienced melt percolation. The Mg2+/Na+ratio indicates that firn or bubbly ice prior to AD 1920 was much less affected by melt percolation than firn or bubbly ice formed after 1920.

Research Grants & Projects

  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(若手研究(B))
    Date (from‐to) : 2009 -2010 
    Author : Yoshinori IIZUKA
     
    北海道大学we reconstructed past aerosol components recent 720kyrBP by using Dome Fuji ice core. As a result, primary components in soluble aerosols were calcium sulfate and sodium chloride during glacial maximums ; on the other hand, primary components were sodium sulfate during interglacials.
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(若手研究(B))
    Date (from‐to) : 2007 -2008 
    Author : Yoshinori IIZUKA
     
    北海道大学
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(S))
    Date (from‐to) : 2003 -2007 
    Author : Yoshiyuki FUJII
     
    国立極地研究所(Objects) The two deep ice cores from Dome Fuji, Antarctica showed the occurrences of a number of abrupt climate and environment changes during the glacial cycles. Objectives of the research project are 1. to establish high time resolution analysis of the deep ice core from Dome Fuji, 2. to reconstruct detailed climatic and environment changes with yearly time scale, and 3. to study scenarios caused the abrupt changes in climate and environment(Results) The high time resolution analyses of ice core in various climate stages (Holocene, LGM, interstadial and glacial stages) were done and the ...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(学術創成研究費)
    Date (from‐to) : 2002 -2006 
    Author : Takeo HONDOH
     
    北海道大学The aim of the present study is to develop a new research field, Nanoglaciology, for better understanding the ice sheet processes on a macroscopic scale on the basis of various microphysical mechanisms involved in the processes, and to clarify the meaning of paleoclimate-and paleoenvironment-signals and their reliabilities. The main results obtained are summarized as ;1. A mass transfer in the firn and the formation process of layer structures : We revealed structural changes of the layering formed at the surface with depth by the use of various experimental methods. Using SEM-EDS and micro...

Educational Activities

Teaching Experience

  • Inter-Graduate School Classes(Educational Program):Antarctic Science
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 極域、南極、北極、海氷、氷床、大気、海洋、気候システム、生態系、南極観測、南極条約
  • Advanced Course in Glacier/Ice Sheet Science
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 氷河、氷床、地球環境、雪、氷、永久凍土、古環境 glacier, ice sheet, earth environment, snow, ice, permafrost, paleoenvironment
  • Inter-Graduate School Classes(Educational Program):Antarctic Science
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 野外観測、降雪、積雪、気象、水文
  • Fundamental Lecture in Paleoclimatology and Paleoceanography
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 古環境,古気候,古海洋,地球温暖化 Paleoenvironment, Paleoclimatology, Paleoceanography, Global warming
  • Fundamental Lecture in Cold Region Sciences
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 雪、氷、極地 snow, ice, polar regions
  • Arts and Science Courses in English 2
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 国際本部
    キーワード : Polar regions, the Antarctic, the Arctic, sea ice, ice sheet, atmosphere, ocean, climate system, ecosystem, Antarctic expeditions, Antarctic treaty
  • Freshman Seminar
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 南極、雪氷学、地球環境学、氷床、アイスコア、気象、海洋、海氷


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