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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.

After the 1980s, atmospheric sulfate reduction is slower than the dramatic reductions in sulfur dioxide (SO2) emissions. However, a lack of observational evidence has hindered the identification of causal feedback mechanisms. Here, we report an increase in the oxygen isotopic composition of sulfate ([Formula: see text]) in a Greenland ice core, implying an enhanced role of acidity-dependent in-cloud oxidation by ozone (up to 17 to 27%) in sulfate production since the 1960s. A global chemical transport model reproduces the magnitude of the increase in observed [Formula: see text] with a 10 to 15% enhancement in the conversion efficiency from SO2 to sulfate in Eastern North America and Western Europe. With an expected continued decrease in atmospheric acidity, this feedback will continue in the future and partially hinder air quality improvements.

For atmospheric gases and aerosols, snow and ice provide a useful archive of paleoenvironmental history. In the northern hemisphere, this archive has been largely limited to Greenland ice, but promising pioneering work has been done recently using chronology of an ice wedge in Barrow, northern Alaska. Here, we investigate past aerosols at the same ice-wedge sampling site, reconstructing the sea-ice fluctuations in the adjacent Beaufort Sea during the Bolling/Allerod (BA) and Younger Dryas (YD) periods. We confirm the integrity of methanesulfonate ion (MS−) concentrations in the BIWS as marine proxies, and then find that the ice wedge has a high MS− concentration through the beginning (coldest) YD periods. The high MS− concentration indicates that even during the coldest YD periods (12,900–12,700 yrBP), the near-shore region in the Alaskan Beaufort Sea near Barrow may not have been completely filled by permanent sea ice.

We provide continuous records of biomass burning molecular tracers (levoglucosan and dehydroabietic acid) in a Greenland ice core collected from the Southeastern Dome (the SE-Dome ice core) over the past several decades to assess the paleoclimatic utility of these tracers in Greenland ice cores. An air mass backward-trajectory analysis indicates that eastern Canada is likely the primary source region of the biomass burning tracers. Comparisons of levoglucosan and dehydroabietic acid data in the SE-Dome ice core and area burned (vegetation fire) events in Canada suggests that the biomass burning tracers in the ice core document most of the pronounced biomass burning events in eastern Canada over the past several decades, confirming that analyses of biomass burning molecular tracers in Greenland ice cores are useful to reconstruct the frequency of significant biomass burning events in a local region. However, our study also highlights that the wind pattern when the biomass burning occurs is decisive for the registration of a biomass burning event in an ice core even though long-term changes in the wind regime associated with decadal-scale climate oscillations do not significantly influence the transport and deposition of biomass burning tracers on the Greenland ice sheet.

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.

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 60.06 m, 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.

The Southeastern Greenland Dome (SE-Dome) has both a high elevation and a high accumulation rate (1.01 m w.e. yr-1), which are suitable properties for reconstructing past environmental changes with a high time resolution. For this study, we measured the major ion fluxes in a 90-m ice core drilled from the SE-Dome region in 2015, and present the records of annual ion fluxes from 1957 to 2014. From 1970 to 2010, the trend of non-sea-salt (nss) SO42- flux decreases, whereas that for NH4+ increases, tracking well with the anthropogenic SOx and NH3 emissions mainly from North America. The result suggests that these fluxes reflect histories of the anthropogenic SOx and NH3 emissions. In contrast, the decadal trend of NO3- flux differs from the decreasing trend of anthropogenic NOx emissions. Although the cause of this discrepancy remains unclear, it may be related to changes in particle formation processes and chemical scavenging rates caused by an increase in sea-salt and dust and/or a decrease in nssSO42-. We also find a high average NO3- flux (1.13 mmol m-2 yr-1) in the ice core, which suggests a negligible effect from post-depositional NO3- loss. Thus, the SE-Dome region is an excellent location for reconstructing nitrate fluxes. Over a decadal timescale, our NO3- flux record is similar to those from other ice cores in Greenland high-elevation sites, suggesting that NO3- concentrations records from these ice cores are reliable.

We estimate the response of snowpack to global warming along with the uncertainty of the snowpack change by using a combination of multiple general-circulation models (GCMs), a single regional atmospheric model, and a one-dimensional multi-layered snowpack model. The target site is Mt. Annupuri in Kutchan, Hokkaido, Japan. The forcing of the snowpack model is taken from dynamically downscaled data from GCMs for the present climate and GCMs in a decade when the global-mean temperature has increased by 2 K from present conditions. The results show that global warming would decrease the monthly-mean snow depth throughout the winter season. Other salient features are the decrease of snow depth by 60 cm with maximum uncertainty of 20 cm at the beginning of the snow ablation period, the occurrence of the snow-depth peak a month earlier, and the dominance of melt forms in an earlier season. The ratio of melt forms for all snowpack layers increases with little uncertainty before the snow ablation period. The ratio of hoar does not change much, even though the air temperature increases. The uncertainty in snowpack evaluation is also discussed. (C) 2017 Elsevier B.V. All rights reserved.

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 dislo...

Monitoring particulate matter is essential to alert the public about health risks. The Terra/MODIS true color image clearly captured a yellow band over Hokkaido prefecture in Japan on 7 March 2016. We investigated whether this event was an Asian dust (Kosa) transport or not with the ground-based observations in Sapporo and Takikawa in Hokkaido and NASA's MERRA-2 re-analysis data. The timing of increased particle number concentrations (PNCs; greater than 0.5 mu m) was clearly measured by a low-cost aerosol sensor at Sapporo and Takikawa in the early afternoon. For this particle size range, the PNC by this aerosol sensor had greater agreement with another commercial instrument for the 1-hourly mean data. The lidar data at Takikawa and NASA's AERONET at Sapporo also implied the increased dust particles (i.e., dominance of non-spherical and coarse particles, respectively), which supported that the PNC increase was due to the dust transport. The hourly PM2.5 data in Sapporo significantly increased in the evening rather than around the noon to early afternoon. We concluded that this event was judged as an Asian dust (Kosa) event in Hokkaido starting from the early afternoon, which was, however, not reported by Japan Meteorological Agency (JMA) based on their visible observations.

To quantify the atmospheric iron deposition on the northern North Pacific region, we measured concentrations of iron in ice cores drilled at Mount Wrangell, Alaska, in 2003 and 2004. The iron concentration profile from 1981 to 2003 showed seasonal peaks each spring. This variation was similar to the seasonal variation in the concentration of mineral dust in the atmosphere in the North Pacific region. The annual iron fluxes calculated from the ice core records ranged from 3.2 to 27.0 mg m(-2) yr(-1), and the temporal variation in the iron lux was significantly correlated with the frequency of severe dust storms occurrence on the East Asian continent (r = 0.65, p < 0.05) and the total number of Kosa days observed in Japan (r = 0.64-0.66, p < 0.05), but not with the precipitation amount in Alaska. We concluded that the amount of iron deposition onto the northern North Pacific is controlled mainly by the emission of dust from the east Asian continent and not by scavenging processes in Alaska.

Previous studies reconstructing summer temperature from an ice core relied on statistical relationship between melt feature and instrumental temperature observed at a nearby station. This study demonstrates a novel method to reconstruct summer temperature from ice layer thickness in an ice core using an energy balance model, in which heat conduction and refreezing of meltwater in firn are taken into account. Using seasonal patterns of the ERA-Interim reanalysis dataset for an ice core site, we calculated amounts of refreezing water within firn under various settings of summer mean temperature (SMT) and annual precipitation, and prepared lookup tables containing these three variables. We then estimated SMT from the refreezing amount and annual accumulation, both available in an ice core. We applied this method to four ice cores drilled in the sites of different climates; two sites on the Greenland Ice Sheet, one in Alaska, and one in Russian Altai Mountains. Reconstructed SMTs show comparable variations to the temperatures observed at nearby stations. Relationships between SMT and ice layer thickness differ site by site, indicating that a single approximation cannot be applicable to estimate SMT. Sensitivity analyses suggest that annual temperature range, amount of annual precipitation and firn albedo setting significantly affect the relationship between SMT and ice layer thickness. This new method provides alternative and independent estimation of SMT from ice cores affected by melting.

To improve surface mass balance (SMB) estimates for the Greenland Ice Sheet (GrIS), we developed a 5 km resolution regional climate model combining the Japan Meteorological Agency Non-Hydrostatic atmospheric Model and the Snow Metamorphism and Albedo Process model (NHM–SMAP) with an output interval of 1 h, forced by the Japanese 55-year reanalysis (JRA-55). We used in situ data to evaluate NHM–SMAP in the GrIS during the 2011–2014 mass balance years. We investigated two options for the lower boundary conditions of the atmosphere: an offline configuration using snow, firn, and ice albedo, surface temperature data from JRA-55, and an online configuration using values from SMAP. The online configuration improved model performance in simulating 2 m air temperature, suggesting that the surface analysis provided by JRA-55 is inadequate for the GrIS and that SMAP results can better simulate physical conditions of snow/firn/ice. It also reproduced the measured features of the GrIS climate, diurnal variations, and even a strong mesoscale wind event. In particular, it successfully reproduced the temporal evolution of the GrIS surface melt area extent as well as the record melt event around 12 July 2012, at which time the simulated melt area extent reached 92.4 %. Sensitivity tests showed that the choice of calculation schemes for vertical water movement in snow and firn has an effect as great as 200 Gt year−1 in the GrIS-wide accumulated SMB estimates; a scheme based on the Richards equation provided the best performance.

Environments along the coast of Greenland are rapidly changing under the influence of a warming climate in the Arctic. To better understand the changes in the coastal environments, we performed researches in the Qaanaaq region in northwestern Greenland as a part of the ArCS (Arctic Challenge for Sustainability) Project. Mass loss of ice caps and marine-terminating outlet glaciers were quantified by field and satellite observations. Measurements and sampling in fjords revealed the important role of glacial meltwater discharge in marine ecosystems. Flooding of a glacial stream in Qaanaaq and landslides in a nearby settlement were investigated to identify the drivers of the incidents. Our study observed rapid changes in the coastal environments, and their critical impact on the society in Qaanaaq. We organized workshops with the residents to absorb local and indigenous knowledge, as well as to share the results and data obtained in the project. Continuous effort towards obtaining long-term observations requiring involvement of local communities is crucial to contribute to a sustainable future in Greenland.

Mineral dust plays a key role in both local and global climates. At high latitudes, atmospheric dust can affect ice-nuclei formation, and surface dust can reduce the albedo as well as increase subsequent ice melting. As a proxy for past climate, mineral dust is preserved in ice cores, but few studies have examined deposited dust in ice cores during the Anthropocene, especially after 2000. We measured dust concentrations in an ice core at the southeastern dome in Greenland (SE-Dome), and reconstructed the annual and seasonal dust fluxes during 1960–2014. We find the annual average flux during 1960–2014 to be 34.8 ± 13.5 mg m−2 yr−1, a value about twice that of ice cores further inland. The more recent part of that period, 2000–2014, has the higher annual flux of 46.6 ± 16.2 mg m−2 yr−1. The annual and autumn dust fluxes highly correlate with air temperature in Tasiilaq (r = 0.61 and 0.50, respectively), a coastal location in southeastern Greenland. Our results suggest that the local dust emissions at the coastal region are increasing due to a decreasing seasonal snow-cover area arising from coastal Greenland warming after 2000.

We analyze snow-pit samples collected in May 2015 at the South East Dome (SE Dome) on the Greenland ice sheet. The analysis includes high-resolution records of δD and δ18O, as well as the major ions, CH3SO3−, Cl−, NO3−, SO42−, Na+, NH4+, K+, Ma2+, and Ca2+. We find that the 3.55-m snow pit recorded temperature and aerosol proxies back to summer or autumn of 2014. This indicates a higher accumulation rate than those at other major drilling sites in Greenland. Due to this high accumulation rate, ion concentrations except Na+ are lower than those typical of the central Greenland ice sheet. Concerning seasonal variability, the Na+, Cl−, Ca2+, Mg2+, and NO3− vary similarly to other sites in Greenland, with the Na+ and Cl− peaking in winter to early spring, Ca2+ peaking in spring, Mg2+ peaking in winter to spring, and NO3− towards a peak in summer while showing smaller peaks in winter to spring. The NH4+ increased in spring, and SO42− increased in autumn to winter at SE Dome. On the other hand, the seasonal trend in the Cl−/Na+ ratio differs from those in the inland region. As we did not fully recover one seasonal cycle, some seasonal peaks may have been missed.

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.

To better understand the reported paleoclimate features and underlying mechanisms in the lowest-latitude region (~28°N to 29°30′N), where 12 major river gorges cross the Himalayas, of the southern Tibetan Plateau, we aim to elucidate the major sources and behavior of modern monsoon air masses in the region based on spatial variations in the δ18O and δ2H of stream water and precipitation, and vegetation during the summer monsoon season. Our main findings were following: The river gorges, high mountain ranges bearing extensive dense vegetation, and stronger solar insolation characteristic of the lowest-latitude region may have functioned for an extended period as the essential geological settings for strongly drawing significant amounts of moisture from the Indian Ocean toward the region without passing through the Yarlung Zangbo basin. The combination of such geological settings specific to this region may have caused its earlier response to the climate amelioration after a cold/dry event, such as the Younger Dryas and Heinrich-1, compared to other regions on the Plateau. Furthermore, gorge-derived monsoon air masses that blew through the lowest-latitude region are highly likely to have more significantly influenced the onset of the climate amelioration after a cold/dry event even in the southwestern, south-central, and southeastern regions, rather than the Yarlung Zangbo-derived monsoon air masses. Therefore, this caused the subsequent expansion of the Indian summer monsoon (ISM) over the Plateau. Thus, with its unique geological setting, the lowest-latitude region has presumably played a critical role as the key region, i.e. the initiator, for the early evolution of the ISM on the Tibetan Plateau by responding to climate amelioration after cold/dry events more rapidly than any other region and drawing gorge-derived monsoon air masses strongly toward the region.

To study the glaciological processes controlling the mass budget of Greenland’s peripheral glaciers and ice caps, field measurements were carried out on Qaanaaq ice cap, a 20 km long ice cap in northwestern Greenland. In the summer of 2012, we measured surface melt rate, ice flow velocity and ice thickness along a survey route spanning the ice margin (200m a.s.l.) to the ice-cap summit (1110m a.s.l.). Melt rates in the ablation area were clearly influenced by dark materials covering the ice surface, where degree-day factors varied from 5.44 mm w.e. K–1 d–1 on a clean surface to 8.26 mm w.e. K–1 d–1 in the dark regions. Ice velocity showed diurnal variations, indicating the presence of surface-meltwater induced basal sliding. Mean ice thickness along the survey route was 120 m, with a maximum thickness of 165 m. Ice velocity and temperature fields were computed using a thermomechanically coupled numerical glacier model. Modelled ice temperature, obtained by imposing estimated annual mean air temperature as the surface boundary condition, was substantially lower than implied by the observed ice velocity. This result suggests that the ice dynamics and thermodynamics of the ice cap are significantly influenced by heat transfer from meltwater and changing ice geometry.

The Institute of Low Temperature Science at Hokkaido University conducted ice-core drilling in alpine glaciers in the northern North Pacific region to reconstruct climate change in this region for the past few hundred years. We drilled two ice cores in the Kamchatka Peninsula, Russia. An ice core with a length of 211 m was drilled on a glacier at the summit caldera of Ushkovsky mountain in 1998. A second core, with a length of 115m (until bedrock was reached), was drilled on a glacier at the summit caldera of Ichinsky mountain in 2006. We drilled three further ice cores in Alaska, USA. Two ice cores with lengths of 50 and 212m were drilled on a glacier at the summit caldera of Mount Wrangell in 2003 and 2004. The third ice core was drilled on the ice divide among three glaciers, Black Rapids, Trident and Susitna glaciers, which represent a flat saddle north of Aurora Peak in the Alaska Range. This paper details the field operations and characteristics of the different ice-drilling systems used and the problems encountered.

Sea salts and halogens in aerosols, frost flowers, and brine play an important role in atmospheric chemistry in polar regions. Simultaneous sampling and observations of frost flowers, brine, and aerosol particles were conducted around Siorapaluk in northwestern Greenland during December 2013 to March 2014. Results show that water-soluble frost flower and brine components are sea-salt components (e.g., Na+, Cl−, Mg2+, K+, Ca2+, Br−, and iodine). Concentration factors of sea-salt components of frost flowers and brine relative to seawater were 1.14–3.67. Sea-salt enrichment of Mg2+, K+, Ca2+, and halogens (Cl−, Br−, and iodine) in frost flowers is associated with sea-salt fractionation by precipitation of mirabilite and hydrohalite. High aerosol number concentrations correspond to the occurrence of higher abundance of sea-salt particles in both coarse and fine modes, and blowing snow and strong winds. Aerosol number concentrations, particularly in coarse mode, are increased considerably by release from the sea-ice surface under strong wind conditions. Sulfate depletion by sea-salt fractionation was found to be limited in sea-salt aerosols because of the presence of non-sea-salt (NSS) SO42−. However, coarse and fine sea-salt particles were found to be rich in Mg. Strong Mg enrichment might be more likely to proceed in fine sea-salt particles. Magnesium-rich sea-salt particles might be released from the surface of snow and slush layer (brine) on sea ice and frost flowers. Mirabilite-like and ikaite-like particles were identified only in aerosol samples collected near new sea-ice areas. From the field evidence and results from earlier studies, we propose and describe sea-salt cycles in seasonal sea-ice areas.

A precise age scale based on annual layer counting is essential for investigating past environmental changes from ice core records. However, sub-annual scale dating is hampered by the irregular intra-annual variabilities of oxygen isotope (δ18O) records. Here, we propose a dating method based on matching the δ18O variations between ice-core records and records simulated by isotope-enabled climate models. We applied this method to a new δ18O record from an ice core obtained from a dome site in southeast Greenland. The close similarity between the δ18O records from the ice core and models enables correlation and the production of a precise age scale, with an accuracy of a few months. A missing δ18O minimum in the 1995/1996 winter is an example of an indistinct δ18O seasonal cycle. Our analysis suggests that the missing δ18O minimum is likely caused by a combination of warm air temperature, weak moisture transport, and cool ocean temperature. Based on the age scale, the average accumulation rate from 1960 to 2014 is reconstructed as 1.02 m yr-1 in water equivalent. The annual accumulation rate shows an increasing trend with a slope of 3.6 mm year-1, which is mainly caused by the increase in the autumn accumulation rate of 2.6 mm year-1. This increase is likely linked to the enhanced hydrological cycle caused by the decrease in Arctic sea ice area. Unlike the strong seasonality of precipitation amount in the ERA re-analysis data in the southeast dome region, our reconstructed accumulation rate suggests a weak seasonality.

AbstarctThe Sea of Okhotsk is the southernmost area in the Northern Hemisphere where seasonal sea ice is produced every year. The formation of sea ice drives thermohaline circulation in the Sea of Okhotsk, and this circulation supports the high productivity in the region. However, recent reports have indicated that sea-ice production in the Sea of Okhotsk is decreasing, raising concern that the decreased sea ice will affect not only circulation but also biological productivity in the sea. To reconstruct climatic changes in the Sea of Okhotsk region, we analyzed an ice core obtained from Ichinskaya Sopka (Mount Ichinsky), Kamchatka. We assumed that the remarkable negative peaks of δD in the ice core were caused by expansion of sea ice in the Sea of Okhotsk. Melt feature percentage (MFP), which indicates summer snowmelt, showed high values in the 1950–60s and the mid-1990s–2000s. The high MFP in the 1950–60s was assumed to be caused by an increase in cyclone activity reaching Kamchatka during a negative period of the Pacific Decadal Oscillation index, and that in the 1990–2000s may reflect the increase in solar irradiation during a positive period of the summer Arctic Oscillation index.

AbstarctAs part of a deep ice-core drilling project, GPS and ice-radar measurements were made in the vicinity of Aurora Peak, Alaska, USA. Surface and bed elevation maps were obtained over an area of 400 m×700 m, which includes the drilling site. Surface flow velocity was measured at 18 locations in the same area. The results showed that the drilling site was situated on a gentle north–south ridge with saddle-shaped surface geometry. The horizontal ice-flow velocity at the drilling site was –1 and the ice generally flowed eastward and westward along the surface slope. The glacier bed slopes to the east and has more complex topography than the ice surface. The drilling site was situated above a bedrock dip, with an ice thickness of 252±10 m. These data constitute important information for estimating the effect of ice flow to the ice core retrieved from the depth of up to 180.17 m.

Samples of first-year sea ice, snow and under-ice water were collected in the southern Sea of Okhotsk in mid-February 2007 and 2008 to elucidate the processes controlling nutrient concentrations in sea ice. Temperature, salinity, oxygen isotopic ratio (δ18O) and inorganic nutrient concentrations (NO3, NH4, NO2, PO4 and SiO2) were measured. Sea ice was categorized into four types; snow–ice, frazil ice, columnar ice and a mixture of granular and columnar ice, based on δ18O composition and ice texture. Frazil ice dominated the total ice thickness (52.8%), and columnar ice was sandwiched between frazil ice layers, indicating dynamic ice-growth processes such as rafting and ridging. Furthermore, the ice was banded by layers of particulate materials (sediment layers), which were frequently encountered during cruises. High NO3 and NH4 concentrations were found in snow and snow–ice implying that these were supplied from the atmosphere with snowfall and incorporated into the sea ice through snow–ice formation. In the sediment-laden layers, which were categorized as frazil ice, NO2, PO4 and SiO2 concentrations were highest of all the ice types and considerably enriched compared to parent seawater, suggesting the remineralization of the particulate organic matter. On the other hand, NO3 concentrations in sediment layers were low (depleted), leading to extremely low N (NO3 + NH4 + NO2): P ratios in sediment layers, from 0.2 to 0.8, with respect to that of under-ice water or Redfield ratio. These results suggest that in part of sediment-laden layers fixed-nitrogen was removed partially as molecular nitrogen (N2) from the sea ice environment by anaerobic nitrate reduction processes (denitrification) by denitrifying bacteria while adding phosphate from associated remineralization of organic phosphorus. The effect of melting of snow and sea ice is dilution for salinity, NO3 and SiO2, no change in NO2 and PO4, and a minor enrichment for NH4 in the mixed layer in spring and early summer. This suggests that snow/ice meltwater with different nutrient ratios than in under-ice water/Redfield ratio is supplied to under-ice water during melt season in April/May in southern Sea of Okhotsk. However, the impact of sediment-laden sea ice cannot be assessed at this point.

We recorded the burial times of temperature sensors mounted on a specially constructed tower to determine snow accumulation during individual storms in the summit caldera of Mount Wrangell, Alaska, USA, (62° N, 144° W; 4100 m a.s.l.) during the accumulation year June 2005 to June 2006. The experiment showed most of the accumulation occurred in episodic large storms, and half of the total accumulation was delivered in late summer. The timing of individual events correlated well with storms recorded upwind, at Cordova, the closest Pacific coastal weather station (200 km south-southeast), although the magnitude of events showed only poor correlation. Hence, snow accumulation at Mount Wrangell appears to be a reflection of synoptic-scale regional weather systems. The accumulation at Mount Wrangell’s summit (>2.5 m w.e.) exceeded the precipitation at Cordova. Although the direct relationship between accumulation of individual storms at the summit of Mount Wrangell and precipitation events at Cordova may be unique in the region, it is useful for interpreting ice cores obtained on Mount Wrangell. This is especially the case here because the high rate of accumulation allows high time resolution within the core.

The first analyses of biological components in glaciers of the Chilean lake district are presented based on microalgae biovolume, pollen and other microorganisms detected in shallow (∼10 m) firn/ice cores. Three cores were retrieved, two at Volcán Mocho-Choshuenco (39°55′ S, 72°02′ W; summit at 2422 m a.s.l; east glacier at 2000 m a.s.l.), and one at the summit of Volcán Osorno (41°06′ S, 72°30′ W; 2652 m a.s.l.). Microalgae, protozoa and pollen quantified in the samples obtained from the two summit cores show clear fluctuations interpreted as seasonal signs. In contrast, δD and many chemical species from the summit cores show strong dampening at depth, probably due to water percolation. The limited information provided by isotopic and chemical analyses is used to support the seasonal interpretation of biological parameters from the summit cores, with microorganism maxima inferred to occur in summer and pollen maxima in spring. A good comparison is found between mass-balance estimations from the Volcán Mocho-Choshuenco summit core and values obtained near that site by means of the stake method. It is concluded that biological analyses of firn/ice cores provide reliable estimations of annual and seasonal markers from these temperate glaciers.

Laboratory experiments were done to better understand the electrical conduction mechanisms of impure, polycrystalline ice as represented by the 2503 m Dome Fuji (Antarctica) ice core. Also, two electrical measurement techniques for ice cores were compared and their usefulness for determining the acidity of ice cores was studied. We measured the electrical conductivity and complex permittivity of 167 slab-ice samples at frequencies from 20 Hz to 1 MHz. Measurements were performed at –21˚C for all samples, and at –110˚ to –20˚C for several samples, to examine the effects of temperature. We found linear relations between the AC loss factor and the molarity of sulfuric acid, and between the high-frequency-limit conductivity and the AC loss factor. Thus, the acidity levels can be determined from the AC loss factor. In contrast, the electrical conductivity measurement (ECM) current correlated weakly with the other parameters; furthermore, the correlation worsens at larger signal. In several samples containing high acidity, the dielectric properties had distinct changes near –81˚C. We argue that these changes were caused by a change from a liquid-vein-mediated conduction mechanism above the eutectic point of the solute/water/ ice system to a solid-phase conduction mechanism at lower temperatures.

A 45.97 m long ice core was recovered in the accumulation area of Glaciar Tyndall (50˚59’05’’ S, 73˚31’12’’W; 1756ma.s.l.), Campo de Hielo Patagόnico Sur (southern Patagonia icefield), during December 1999. the firn core was subjected to visual stratigraphic observation and bulk density measurements in the field, and later to analyses of water isotopes (δ18O, δD), major dissolved ions and snow algal biomass. the drillhole remained dry down to about 43 m depth, where a water-soaked layer appeared. Seasonal cycles were found for δ18O, δD and the D-excess, although the amplitudes of the cycles decreased with depth. Major dissolved ions (Na+, K+, Mg2+, Ca2+, Cl–, SO42–) and algal biomass exhibit rapid decreases in the upper 3 m, probably due to meltwater elution. Annual increments defined by the δ18O and D-excess peaks suggest that the minimum net accumulation rates at this location were 17.8ma–1 in 1997/98–1998/99 and 411.0 ma–1 in 1998/99–1999/2000. These are much higher values than those previously obtained from past ice-core studies in Patagonia, but are of the same order of magnitude as those predicted from various observations in ablation areas of Patagonian glaciers.