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We reconstructed surface mass balance (SMB) around Dome Fuji, Antarctica, over the last 5000 years using the data from 15 shallow ice cores and seven snow pits. The depth–age relationships for the ice cores were determined by synchronizing them with a layer-counted ice core from West Antarctica (WAIS Divide ice core) using volcanic signals. The reconstructed SMB records for the last 4000 years show spatial patterns that may be affected by their locations relative to the ice divides around Dome Fuji, proximity to the ocean, and wind direction. The SMB records from the individual ice cores and snow pits were stacked to reconstruct the SMB history in the Dome Fuji area. The stacked record exhibits a long-term decreasing trend at -0.037±0.005 kg m−2 per century over the last 5000 years in the preindustrial period. The decreasing trend may be the result of long-term surface cooling over East Antarctica and the Southern Ocean and sea ice expansion in the water vapor source areas. The multidecadal to centennial variations of the Dome Fuji SMB after detrending the record shows four distinct periods during the last millennium: a mostly negative period before 1300 CE, a slightly positive period from 1300 to 1450 CE, a slightly negative period from 1450 to 1850 CE with a weak maximum around 1600 CE, and a strong increase after 1850 CE. These variations are consistent with those of previously reconstructed SMB records in the East Antarctic plateau. The low accumulation rate periods tend to coincide with the combination of strong volcanic forcings and solar minima for the last 1000 years, but the correspondence is not clear for the older periods, possibly because of the lack of coincidence of volcanic and solar forcings or the deterioration of the SMB record due to a smaller number of stacked cores.

The 13th Symposium on Polar Science/Ordinary sessions [OM] Polar meteorology and glaciology, Wed. 16 Nov.

The 13th Symposium on Polar Science/Ordinary sessions [OM] Polar meteorology and glaciology, Wed. 16 Nov.

The 13th Symposium on Polar Science/Ordinary sessions [OM] Polar meteorology and glaciology, Wed. 16 Nov.

We reconstructed surface mass balance (SMB) around Dome Fuji, Antarctica, over the last 5000 years using the data from 15 shallow ice cores and 7 snow pits. The depth-age relationships for the ice cores were determined by synchronizing them with a layer-counted ice core from West Antarctica (WAIS Divide ice core) using volcanic signals. The reconstructed SMB records for the last 4000 years show spatial patterns that may be affected by their locations relative to the ice divides around Dome Fuji, proximity to the ocean, and wind direction. The SMB records from the individual ice cores and snow pits were stacked to reconstruct the SMB history in the Dome Fuji area. The stacked record exhibits a long-term decreasing trend at −0.037±0.005 kg m-2 per century over the last 5000 years in the preindustrial period. The decreasing trend may be the result of long-term surface cooling over East Antarctica and the Southern Ocean, and sea-ice expansion in the water vapor source areas. The multidecadal to centennial variations of the Dome Fuji SMB after detrending the record shows four distinct periods during the last millennium: mostly negative period before 1300 C.E., slightly positive for 1300–1450 C.E., slightly negative for 1450–1850 C.E. with a weak maximum around 1600 C.E., and strong increase after 1850 C.E. These variations are consistent with those of previously reconstructed SMB records in the East Antarctic plateau. The low accumulation rate periods tend to coincide with the combination of strong volcanic forcings and solar minima for the last 1000 years, but the correspondence is not clear for the older periods, possibly because of the lack of coincidence of volcanic and solar forcings, or the deterioration of the SMB record due to smaller number of stacked cores.

The retrieval of continuous ice core records of more than 1 Myr is an important challenge in palaeo-climatology. For identifying suitable sites for drilling such ice, knowledge of the subglacial topography and englacial layering is crucial. For this purpose, extensive ground-based ice radar surveys were carried out over Dome Fuji in the East Antarctic plateau during the 2017/18 and 2018/19 austral summers by the Japanese Antarctic Research Expedition, on the basis of ground-based radar surveys conducted over the previous ∼ 30 years. High-gain Yagi antennae were used to improve the antenna beam directivity, thereby significantly decreasing hyperbolic features of unfocused along-track diffraction hyperbolae in the echoes from mountainous ice–bedrock interfaces. We combined the new ice thickness data with the previous ground-based data, recorded since the 1980s, to generate an accurate high-spatial-resolution (up to 0.5 km between survey lines) ice thickness map. This map revealed a complex landscape composed of networks of subglacial valleys and highlands. Based on the new map, we examined the roughness of the ice–bed interface, the bed surface slope, the driving stress of ice and the subglacial hydrological condition. These new products and analyses set substantial constraints on identifying possible locations for new drilling. In addition, our map was compared with a few bed maps compiled by earlier independent efforts based on airborne radar data to examine the difference in features between datasets. Our analysis suggests that widely available bed topography products should be validated with in situ observations where possible.

Atmospheric sea-salt and halogen cycles play important roles in atmospheric science and chemistry including cloud processes and oxidation capacity in the Antarctic troposphere. This paper presents a review and summarizes current knowledge related to sea-salt and halogen chemistry in the Antarctic. First, presented are the seasonal variations and size distribution of sea-salt aerosols (SSAs). Second, SSA origins and sea-salt fractionation on sea-ice and ice sheets on the Antarctic continent are presented and discussed. Third, we discuss SSA release from the cryosphere. Fourth, we present SSA dispersion in the Antarctic troposphere and transport into inland areas. Fifth, heterogeneous reactions on SSAs as a source of reactive halogen species and their relationship with atmospheric chemistry are shown and discussed. Finally, we attempt to propose an outlook for obtaining better knowledge related to sea-salt and halogen chemistry and their effects on the Antarctic and the Arctic.

Tiny samples of ancient atmosphere in air bubbles within ice cores contain argon (Ar), which can be used to reconstruct past temperature changes. At a sufficient depth, the air bubbles are compressed by the overburden pressure under low temperature and transform into air-hydrate crystals. While the oxygen (O2) and nitrogen (N2) molecules have indeed been identified in the air-hydrate crystals with Raman spectroscopy, direct observational knowledge of the distribution of Ar at depth within ice sheet and its enclathration has been lacking. In this study, we applied scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to five air-hydrate crystals in the Greenland NEEM ice core, finding them to contain Ar and N. Given that Ar cannot be detected by Raman spectroscopy, the method commonly used for O2 and N2, the SEM-EDS measurement method may become increasingly useful for measuring inert gases in deep ice cores.

The retrieval of continuous ice core records of more than 1 Myr is an important challenge in palaeo-climatology. For identifying suitable sites for drilling such ice, the knowledge of the subglacial topography and englacial layering is crucial. For this purpose, extensive ground-based ice radar surveys were done over Dome Fuji in the East Antarctic plateau during the 2017–2018 and 2018–2019 austral summers by the Japanese Antarctic Research Expedition, on the basis of ground-based radar surveys conducted over the previous ~ 30 years. High-gain Yagi antennae were used to improve the antenna beam directivity and thus attain a significant decrease in hyperbolic features in the echoes from mountainous ice-bedrock interfaces. We combined the new ice thickness data with the previous ground-based data, recorded since the 1980s, to generate an accurate high-spatial-resolution (up to 0.5 km between survey lines) ice thickness map. This map revealed a complex landscape composed of networks of subglacial valleys and highlands, which sets substantial constraints for identifying possible locations for new drilling. In addition, our map was compared with a few bed maps compiled by earlier independent efforts based on airborne radar data to examine the difference in features between sets of the data.

Seasonal changes of meteorological and ground surface conditions can cause seasonal changes of source area of mineral particles supplied to the Greenland ice sheet. Difference in metal composition and size distribution of them reflects their source area difference. To clarify seasonal changes in the source area of mineral particles, we examined the metal composition and size distribution of them in snow pit samples obtained from EGRIP (East Greenland Ice Core Project).In summer 2017, we dug a 2.01 m snow pit at EGRIP camp. Snow samples were collected at 0.03 m intervals. The snow samples were melted, then fractions of them were analyzed for the particle size distribution (0.52-12μm) with a Coulter counter (Beckman Coulter: Multisizer 4). Other fractions of the samples were treated with a microwave acid digestion method to decompose particulates. Total concentrations of Al, Ca and Na in samples were measured by inductively coupled plasma mass spectrometry.Total concentrations of Al (t-Al) and concentrations of non-sea-salt Ca (nssCa) showed peak values in winter to spring layers. In those layers, nssCa/t-Al ratios and volume fractions of fine particles (

The storage of melted snow and/or ice samples from snow pits and ice cores in a refrigerator for long durations may be limited by an increase in particle concentration caused by microbial growth after approximately 1–2 weeks. In this study, we examined an ultraviolet (UV) disinfection method for the storage of melted snow and/or ice samples. Surface snow obtained from Glacier No. 31 in the Suntar-Khayata Range, eastern Siberia, Russia was divided into two portions for UV treatment and untreated controls. Particle concentrations in the samples were measured using a Coulter counter (Multisizer 4e; Beckman Coulter, USA). Whereas the particle concentration in untreated samples increased, no obvious increase was observed over 53 days in the samples subjected to UV treatment. In addition, the original particle concentrations were unaffected by UV treatment. These findings indicate that the antimicrobial effect of UV radiation is effective for long-term sample storage of melted water samples. A detailed analysis of the particle size distribution for untreated samples indicated that particles of 0.7–1.2 µm appeared within the first 7–14 days. Measurements using a viable particle counter (XL-10BT2 and XL-28A1; RION Co. Ltd., Japan) confirmed that these were biological particles, suggesting that microbial growth occurs during this period. Subsequently, the particles shifted to a smaller size and a higher concentration, suggesting that the decomposition of microorganisms occurred in the water samples. Therefore, the size distribution of particles in untreated samples reflected the growth and decomposition of microorganisms over time.

Temporal variability in surface mass balance (SMB) on the Greenland ice sheet is important for understanding the mass balance of the ice sheet. Additionally, knowledge of the spatial variability in SMB at ice core drilling sites helps to interpret the spatial representativeness of SMB data obtained from a single ice core. In this study, to investigate the spatiotemporal variability in recent SMB in the East Greenland Ice Core Project (EGRIP) area in the northeastern Greenland ice sheet, pit observations were made at six sites in the summers of 2016–2018. In all pits, depth profiles of water isotope ratios showed clear seasonal variations. The annual SMB differed from site to site, which is probably due to post-depositional redistribution of snow caused by wind erosion and snowdrift. However, the multiple-site averages of annual SMBs, which ranged from 134 to 157 mm w. e. yr−1 (average 146 mm w. e. yr−1) during 2009–2017, were very similar. This indicates that annual SMBs in the EGRIP area were nearly constant in this period. The seasonal SMBs in the EGRIP area tended to be larger in the summer–winter period than in the winter–summer period.

The 11th Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 3 Dec.

The 11th Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 3 Dec.

The 11th Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 3 Dec.

The 11th Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 3 Dec.

The 11th Symposium on Polar Science/Special session: [S] Accelerating Arctic research: Recent progress and future prospect of Arctic research, Poster presentations, Mon. 16 Nov. - Fri. 18 Dec.

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 5 Dec. / 2F Auditorium , National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 5 Dec. / 2F Auditorium , National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 5 Dec. / 2F Auditorium , National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 5 Dec. / 2F Auditorium , National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / Entrance Hall (1st floor) , National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / Entrance Hall (1st floor) , National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Research

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / Entrance Hall (1st floor) , National Institute of Polar Research

The Ninth Symposium on Polar Science/Ordinary sessions: [OM] Polar meteorology and glaciology, Wed. 5 Dec. / 3F Multipurpose Conference room, National Institute of Polar Research

The Ninth Symposium on Polar Science/Ordinary sessions: [OM] Polar meteorology and glaciology, Wed. 5 Dec. / Entrance Hall (1st floor), National Institute of Polar Research

We collected snow samples from two pits with depths of 4.02 and 3.18 m at the East Greenland Ice Core Project camp (75°37′N, 35°59′W), Greenland in the summer of 2016 to estimate recent annual snow deposition and examine seasonal variation in major ion species, stable isotopes of water and microparticles (dust). Dating based on clear seasonal variation in chemical components indicated that the 4.02- and 3.18-m-deep pits included snow deposition corresponding to ten years from 2006 to 2016 and seven years from 2009 to 2016, respectively. The mean values for annual snow deposition for the 4.02-m-deep pit were 138 and 145 mm yr−1 in water equivalent (mm w.e. Yr−1) in 2006–2016 and 2009–2016, respectively. The average deposition for the 3.18-m-deep pit was 149 mm w.e. Yr−1 between 2009 and 2016. Seasonal variation in concentrations of major ion species and dust were similar to those previously reported for Greenland. The maximum Cl−/Na+ concentration ratios in the summer were much higher than the ratios at other sites in Greenland.

Pollen taxa in sediment samples can be identified based on morphology. However, closely related species do not differ substantially in pollen morphology, and accurate identification is generally limited to genera or families. Because many pollen grains in glaciers contain protoplasm, genetic information obtained from pollen grains should enable the identification of plant taxa at the species level. In the present study, species identification of Pinus pollen grains was attempted using whole-genome amplification (WGA). We used pollen grains extracted from surface snow (depth, 1.8&ndash, 1.9 m) from the Belukha glacier in the summer of 2003. WGA was performed using a single pollen grain. Some regions of the chloroplast genome were amplified by PCR, and the DNA products were sequenced to identify the pollen grain. Pinus includes approximately 111 recognized species in two subgenera, four sections, and 11 subsections. The tree species Pinus sibirica and P. sylvestris are currently found at the periphery of the glacier. We identified the pollen grains from the Belukha glacier to the level of section or subsection to which P. sibirica and P. sylvestris belong. Moreover, we specifically identified two pollen grains as P. sibirica or P. cembra. Fifteen species, including P. sibirica, were candidates for the remaining pollen grain.

The aim of this study was to estimate the age of glacier ice in the No. 31 Glacier in the Suntar-Khayata Range of eastern Siberia by performing dating of insects thought to be long-legged fly species (Dolichopodidae) as well as plants (species unknown) fragments preserved in the ice. Ice samples containing organisms were collected at depths of 0.4–1.1 m at five points from the middle to lowest parts of the glacier in 2013. The age of an insect collected at the lowest point on the glacier was estimated as 2038 ± 32 yr B.P. Insects collected at higher points had a modern or near-modern radiocarbon age. The age of plant fragments collected at the uppermost and middle points was 1531 ± 44 and 1288 ± 26 yr B.P., respectively, and that of a mixture of plant and insect fragments collected at the lowest point was 9772 ± 42 yr B.P. When comparing specimens collected at the same point, the plant fragments were found to be older than the insects. In 2012–2014 observations, some living insects were found on the glacier, and thus the age of the insects appears to correspond to the age of the ice. On the other hand, the plant fragments might have already aged since detachment from the source plants. This study found an approximately 2000-year gap in the age of the ice between the lowest and higher points. Annual mass balance observations from 2012 to 2014 showed that in recent years, the glacier sometimes had no accumulation area. Therefore, the wide gap in the age of ice may be due to a difference in past melting processes between the lowest and higher points on the glacier.

This study analyzed pollen in snow pits dug in late summer (2008–2011) on the upstream side of Potanin Glacier, a summer accumulation-type glacier in the Mongolian Altai, to reconstruct the recent snow depositional environment, particularly melting conditions. Annual snow pit observations were performed at sites 0 and 4 (3752 and 3890 m a.s.l., respectively). Seasonal layers in the pits were identified according to the presence of pollen from three taxa (Betulaceae, Pinus, and Artemisia), which have different pollen seasons typically between May and early September. The pollen-dating method was successful in snow pits where conventional methods such as ice layer dating and use of δ 18O records were unreliable due to significant melting. Depths of pollen concentration peaks for the three taxa differed annually at both sites. In some years, concentration peaks of the three pollen taxa were found at different depths, but in other years, peaks associated with each taxon were found at the same depth. This difference was explained by summer temperature. Snow melting during the relatively warm summers of 2007 and 2008 caused pollen grains to concentrate on the glacier surface, producing peaks at the same depth. In contrast, snow melting during the relatively cool summer of 2009 did not substantially alter pollen grain location, and each peak thus retained its original depth. The median temperatures in 2010 and 2011 corresponded to pollen concentrating on the glacier surface at site 0 but retaining their original position at site 4.

南極地域観測第Ⅶ期5か年計画に基づき，2007/2008 年の南極の夏期シーズンに，国立極地研究所を中心とした研究グループは，スウェーデンの研究者グループと共同で，東南極内陸域のドロンイングモードランド地域の内陸部の氷床環境調査を実施した．本報告は，現地調査前に5年間を費やした研究計画の企画検討の経過や行った事前準備と，現地野外観測を終了した後の6年間に得られた研究成果の概要をまとめるものである．本プロジェクトの調査により，南極内陸高原部の氷床環境の時空間分布について，多くの科学的知見が明らかになった．本報告はその概要を報告する．現地調査の実行の経過は別途の報告に記述する．, 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.

[1] 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.

Measurements of aerosol number concentrations and direct aerosol sampling were conducted on continental Antarctica during the traverse of the Japanese–Swedish joint Antarctic expedition (JASE) from 14 November 2007 until 24 January 2008. Aerosol concentrations in background conditions decreased gradually with latitude in inland regions during the traverse. The lowest aerosol number concentrations were 160 L−1 in Dp > 0.3 μm, and 0.5 L−1 in Dp 2 μm. In contrast, aerosol concentrations reached 3278 L−1 in Dp > 0.3 μm, and 215 L−1 in Dp > 2 μm under strong wind conditions. The estimated aerosol mass concentrations were 0.04–5.7 μg m−3. Single particle analysis of aerosol particles collected during the JASE traverse was conducted using a scanning electron microscope equipped with an energy dispersive x ray spectrometer. Major aerosol constituents were sulfates in fine mode, and sulfate, sea salts, modified sea salts, and fractionated sea salts in coarse mode. K-rich sulfates, Mg-rich sulfate, Ca-rich sulfates, and minerals were identified as minor aerosol constituents. Horizontal features of Cl / Na ratios imply that sea-salt modification (i.e. Cl loss) occurred on the Antarctic continent during the summer. Most sea-salt particles in the continental region near the coast were modified with acidic sulfur species such as H2SO4 and CH3SO3H. By contrast, acidic species other than the acidic sulfur species (likely HNO3) contributed markedly to sea-salt modification in inland areas during the traverse. Mg-rich sea-salt particles and Mg-free sea-salt particles were present in coarse and fine modes from the coast to inland areas. These sea-salt particles might be associated with sea-salt fractionation on the snow surface of continental Antarctica.