Long time series of Antarctic sea ice extent(SIE) are important for climate research and model forecasting. A historic ice extent in the Ross Sea in early austral winter was rebuilt through sea salt ions in the DT401 ice core in interior East Antarctica. El Ni?o-Southern Oscillation(ENSO) had a significant influence on the sea salt deposition in DT401 through its influence on the Ross Sea SIE and the transport of sea salt inland. Spectral analysis also supported the influence of ENSO with a significant 2–6 a periodicity band. In addition, statistically significant decadal(10 a) and pentadecadal(50–70 a) periodicities suggested the existence of a teleconnection from the Pacific decadal oscillation(PDO), which originated from sea surface temperature anomalies in the tropical Pacific Ocean. The first eigenvector of the empirical orthogonal function analysis(EOF1) showed lower values during the Medieval Warm Period(MWP), while higher values were found in the Little Ice Age(LIA). A higher frequency of ENSO events were found in the cold climatic stage. The post 1800 AD period was occupied by significant fluctuations of the EOF1, and PDO may be one of the influencing factors. The EOF1 values showed moderate fluctuations from 680 BC to 1000 AD, showing that the climate was relatively stable in this period.
LI ChuanJinREN JiaWenXIAO CunDeHOU ShuGuiDING MingHuQIN DaHe
Recent snow height measurements(2008–15) from nine automatic weather stations(AWSs) on the Ross Ice Shelf are used to examine the synoptic and seasonal variability in snow accumulation,and also to evaluate the performance of the Antarctic Mesoscale Prediction System(AMPS) for precipitation. The number of snow accumulation events varies from one station to another between 2008 and 2015,thus demonstrating geographic dependence. The interannual variability in snow accumulation is too high to determine its seasonality based on the current AWS observations with limited time coverage.Comparison between the AMPS and AWS snow height measurements show that approximately 28% of the AWS events are reproduced by AMPS. Furthermore,there are significant correlations between AMPS and AWS coincident event sizes at five stations(p < 0.05). This finding suggests that AMPS has a certain ability to represent actual precipitation events.
This paper gives an overview of the current understanding of the observations of black carbon(BC) in snow and ice, and the estimates of BC deposition and its radiative forcing over the Arctic. Both of the observations and model results show that, in spring, the average BC concentration and the resulting radiative forcing in Russian Arctic > Canadian and Alaskan Arctic > Arctic Ocean and Greenland. The observed BC concentration presented a signi?cant decrease trend from the Arctic coastal regions to the center of Arctic Ocean. In summer, due to the combined effects of BC accumulation and enlarged snow grain size, the averaged radiative forcing per unit area over the Arctic Ocean is larger than that over each sector of the Arctic in spring. However, because summer sea ice is always covered by a large fraction of melt ponds, the role of BC in sea ice albedo evolution during this period is secondary. Multi-model mean results indicate that the annual mean radiative forcing from all sources of BC in snow and ice over the Arctic was ~0.17 W m^(-2). Wet deposition is the dominant removal mechanism in the Arctic, which accounts for more than 90% of the total deposition. In the last part, we discuss the uncertainties in present modeling studies, and suggest potential approaches to reduce the uncertainties.
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.
Based on stake measurements conducted along the Chinese Antarctic traverse since Jan.1999,we investigated the characteristics of surface mass balance(SMB)and related climate consequences from Zhongshan Station to Dome A,East Antarctica.Spatial analysis suggests that post-depositional processes have a great impact on surface morphology;thus,the representativeness of a single measurement should be discussed in conjunction with local climate features.The comparison among snow accumulation,ice sheet thickness,surface elevation,and ice velocity indicates that the bedrock topography has an indirect connection with the SMB patterns through controlling the surface topography and local climate.The observation reveals that the Lambert Glacier Basin has been experiencing increasing mass input(4.5%),whereas the inland area has experienced a 6%loss,since 2005.An overall estimation of the SMB along the route is 71.3±44.3 kg m?2 a?1,but the annual and regional variation is considerable.Tendency analysis shows that there are four sections with different SMB patterns as a result of three moisture sources and surface climatic discrepancy in the Antarctic inland.This study is the first to identify four SMB patterns from the coast to the Dome area and should provide a valuable contribution to modeling and remote sensing on a continental scale.
DING MingHuXIAO CunDeLI ChuanJinQIN DaHeJIN BoSHI GuiTaoXIE AiHongCUI XiangBin
