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.
In recent decades, the development of continuous flow analysis (CFA) technology for ice core analysis has enabled greater sample throughput and greater depth resolution compared with the classic discrete sampling technique. We developed the first Japanese CFA system at the National Institute of Polar Research (NIPR) in Tokyo. The system allows the continuous analysis of stable water isotopes and electrical conductivity, as well as the collection of discrete samples from both inner and outer parts of the core. This CFA system was designed to have sufficiently high temporal resolution to detect signals of abrupt climate change in deep polar ice cores. To test its performance, we used the system to analyze different climate intervals in ice drilled at the NEEM (North Greenland Eemian Ice Drilling) site, Greenland. The quality of our continuous measurement of stable water isotopes has been confirmed through a comparison with different datasets. Moreover, our system presents a better measurement efficiency to resolve the signal of electrical conductivity in the ice core sample than that obtained with a similar system developed by the University of Bern, Switzerland, during a field campaign at NEEM camp.
Snow algae are cold-tolerant photosynthetic microbes growing on snow and ice. In order to investigate the factors affecting snow algal growth, the temporal changes in algal abundance on surface snow were studied over four winters in an experimental station in Niigata Prefecture, Japan, where seasonal snow is usually present from late December to early April. Snow algae appeared on the snow surface in February, and the initial algae were likely to be deposited on the snow by winds. The timing of the algal appearance varied among years, from early-February in 2011 to late-February in 2015, and is likely to be determined by a period of no snowfall and air temperatures above the melting point. Algal abundance generally increased until the disappearance of snow. The maximum algal concentration was found in 2011, which corresponds to the year when the period from algal appearance to the disappearance of snow was the longest (80days) among the four winters. The results suggest that snow algae keep growing unless snowfall occurs and air temperature drops to freezing point, and that the algal abundance is likely to be correlated with the duration of algal growth. The algal growth curve in 2011 could be reproduced by a Malthusian model with a growth rate of 0.22 d−1.
This paper outlines meteorological and glaciological observations of Glacier No. 31 in the Suntar-Khayata Range, east Siberia, obtained from 2012 to 2014. We set up meteorological instruments and seven stakes on the glacier for the purpose of measuring surface mass balance and flow velocity. The mean air temperature between July 8, 2012 and August 7, 2013 was －13.9°C at site 31-2 (2446m a.s.l.) and the minimum temperature was －46.0°C. The air temperature on the glacier from November to April was approximately 10°C higher than that at Oymyakon village, suggesting a temperature inversion phenomenon, which typically occurs during winter in this region. The snow depth records show that snow increased at the beginning and end of winter, and that there was almost no change from the beginning of October until the end of April. The maximum snow depth from the previous summer was 158cm at site 31-2 on May 28, 2013. The average annual surface mass balance for the 6sites was －1256mm water equivalent (w.e.) during the period from August 24, 2012 to August 16, 2013, indicating that ablation proceeded rapidly in all areas of the glacier. Surface flow velocity in 2013/2014 was 1.57ma−1 at the approximate midpoint of the glacier, and was much slower than that measured during the IGY (International Geophysical Year) period (4.5ma−1) in 1957/1958. The length and areal extent of the glacier were 3.85km and 3.2km2 in 1958/1959 and 3.38km and 2.27km2 in 2012/2013, respectively, showing a decrease over the last 54years.