Surface snow samples were collected during the 14th(1997/1998)and 24th(2007/2008)Chinese National Antarctica Research Expeditions along a transect from Zhongshan Station to Dome A.The stable oxygen isotope ratios of these samples were measured to investigate their relationships with temperature and geographical parameters(latitude,longitude,altitude and distance to the coast).The results reveal a strong positive correlation(R=0.945)betweenδ18O and mean annual temperature,with a gradient of 0.84‰°C-1,which is a little higher than that in Terre Adelie Land.Regression analyses also show that theδ18O of surface snow is strongly correlated with distance to the coast(R=0.942),latitude(R=0.942),and altitude(R=0.941).But no significant correlation was found betweenδ18O and longitude in study area.Altitude should be the most important factor influencing the δ18O distribution because of distinctive topography.Theδ18O-altitude and T-altitude gradients along this transect are determined to be-1.1‰/100 m and 1.31°C/100 m,respectively.
DING MingHuXIAO CunDeJIN BoREN JiaWenQIN DaHeSUN WeiZhen
The heights of automatic weather station (AWS) sensors over the Antarctic ice sheet are nominal and change with snow accumulation or ablation.Therefore,the measured data may not be used directly.In this study,we analyzed the impact of snow accumulation on AWS observations using continuous measurements from three AWS that were deployed on the traverse route from the Zhongshan Station to Dome A over East Antarctica.We then corrected the measured air temperature to account for changes in the sensor height relative to the snow surface to improve the authenticity and representativeness of the observation data from the AWS.The results show that (i) the annual mean snow accumulations at Dome A,Eagle and LGB69 were approximately 0.11 m,0.30 m and 0.49 m,respectively,and the corresponding annual mean air temperature differences between the corrected and measured values at 1 m in height were 0.34℃,0.29℃ and 0.35℃;(ii) the impact on air temperature from accumulation decreases with height from the surface;(iii) the air temperature difference between the corrected and measured values was not directly proportional to the snow accumulation but was related to the seasonal air temperature variations and the intensity of the local surface inversion;and (iv) the averaged corrected air temperature was higher than the measured values except during the summer when there were days without temperature inversion.The magnitude of the temperature difference between the corrected and measured was mainly determined by snow accumulation and the intensity of the local surface inversion.
This study investigates the regional distribution of marine aerosol originated species(Na+, Cl-, nss-SO42- and MSA) in the snow pits(or firn cores) collected along a transect between Zhongshan Station and the Grove Mountain area(450 km inland) on the eastern side of the Lambert Glacier Basin. Concentrations of Na+ and Cl- decrease exponentially with distance from the coast to 100 km inland(i.e., 1500 m a.s.l.). Statistical results demonstrate that distance from the coast inland and elevation affect the concentration of sea-salt originated ions in inland areas significantly. Increase of Cl-/Na+ ratio and higher variability in its standard deviation suggest that there are other sources of ions in addition to sea-salt in inland areas of the Antarctic continent. The concentrations of Na+ and Cl- from nine sampling sites in the Grove Mountain area are relatively higher than those from sites along CHINARE transect, although all sites are at similar distance inland. This phenomenon indicates that the barrier effect of the mountain may be the most important factor influencing ion deposition. In addition, nss-SO42- and MSA vary differently, with nss-SO42- decreasing with distance more significantly. This implies that sources and transporting pathways influence the deposition of the two sulfur compounds considerably, being supported by the spatial pattern of correlation coefficients between the nss-SO42- and MSA.
Surface snow samples were collected during the 14th(1997/1998)and 24th(2007/2008)Chinese National Antarctica R...
DING MingHu~(1,2,3*),XIAO CunDe~2,JIN Bo~4,REN JiaWen~2,QIN DaHe~2 & SUN WeiZhen~2 1 Division of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China
Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded by an automatic weather station (AWS) was -58.3℃ in 2005 and -58.2℃ in 2006, re-spectively. The 10-m firn temperature is an approximation of the annual mean air temperature (AMAT), and this is the lowest AMAT that has been recorded on the surface of the Earth. The stable isotopic ratios (δ 18O and δ D) of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C, Dome F, Dome B and Vostok. These facts indicate that Dome A is the "pole of cold" on the Earth. The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm, equaling 0.016 m water equivalent per year, the lowest precipitation ever recorded from Antarctica. Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.
