Seasonal variations of the near surfacelayer parameters over the Antarctic ice sheet in Princess Elizabeth Land,East Antarctica

Analysis of sensible heat flux(Qh),latent heat flux(Qe),Richardson number(Ri),bulk transport coefficient(Cd) and katabatic winds are presented by using the meteorological data in the near surface layer from an automatic weather station(AWS) in Princess Elizabeth Land,East Antarctica ice sheet and the data of corresponding period at Zhongshan station in 2002.It shows that annual mean air temperature at LGB69 is-25.6°C,which is 16.4°C lower than that at Zhongshan,where the elevation is lower and located on the coast.The temperature lapse rate is about 1.0°C/110 m for the initial from coast to inland.The turbulence heat flux at LGB69 displays obvious seasonal variations with the average sensible heat flux-17.9 W/m2 and latent heat flux-0.9 W/m2.The intensity(Qh+Qe) of coolling source is-18.8 W/m2 meaning the snow surface layer obtains heat from atmosphere.The near surface atmosphere is near-neutral stratified with bulk transport coefficients(Cd) around 2.8×10-3,and it is near constant when the wind speed higher than 8 m/s.The speed and the frequency of easterly Katabatic winds at LGB69 were higher than that at Zhongshan Station.     

250 years of accumulation, oxygen isotope and chemical records in a firn core from Princess Elizabeth Land, East Antarctica

A 51.85-m firn core collected from site DT001 (accumulation rate 127 kgm-2a-1, mean annual temperature -33.1 oC) on Princess Elizabeth Land, East Antarctica, during the 1996-97 Chinese First Antarctic Inland Expedition has been analyzed for chemical composition and oxygen isotope ratio. A comparison between the seasonal variations of major ions was carried out in order to reduce the dating uncertainty, using the volcanic markers as time constrains. A deposition period of 251 years was determined. The calculated accumulation rates display an increasing trend before 1820, while after 1820, the trend of the accumulation is not obvious. Overall, temperature change in the region shows a slight increasing trend over the past 250 years. But, notably, a temperature decline of -2 oC is observed from 1860 to the present. This feature, at odds with the warming trend over the past century recorded in both hemispheres, likely reflects a regional characteristic related to the lack of a high latitude/low latitude link in the Southern Hemisphere circulation patterns. The results of the glaciochemical records of the firn core show that the mean concentrations of Cl-, Na+ and Mg2+ are similar to those reported from other sites in East Antarctica. However, the mean concentration of Ca2+ is much higher than that reported from other regions, suggesting the influence of the strong local terrestrial sources in Princess Elizabeth Land. There is no evidence of a positive correlation between NO3- concentrations and solar activity (11-year solar cycle and solar cycle length), although solar proton events may account for some of the NO3- peak values in the record.     

南极伊利莎白公主地250年来雪芯累积、氧同位素与化学研究

1Introduction In the ongoing discussion of climate change,the mass balance of Antarctica has received increasing attention during recent decades,since its reaction to global warming will strongly influence sea-level change(Schlosser and Oerter,2002).Many …     

南极伊利莎白公主地250年来海、陆盐离子浓度特征

中国首次南极内陆冰盖考察获得的50m冰芯的雪冰化学资料研究表明:南极伊利莎白公主地海盐离子浓度季节变化特征明显,为冰芯定年提供了可靠的依据。伊利莎白公主地雪冰中Cl^-、Na⁺和Mg²⁺等海盐离子浓度与南极冰盖其它地方相当,而Ca²⁺含量异常的高,可能与局地较强的陆地源有关。近150年来,伊利莎白公主地海盐离子浓度具有明显升高的趋势,可能是整个南半球100多年来升温的结果。     

The concentration variation features of sea salt ions and non sea salt ions in a firn core recovered from Princess Elizabeth Land, East Antarctica

A 51.85 m firn core drilled in Princess Elizabeth Land, Antarctica, during the 1996-1997 Chinese First Antarctic Inland Expedition, has been measured for δ 18 O and major ions. Based on the high quality data of the seasonal variations of major ions, the firn core was dated with errors within ±3 years. The 51.85 m firn core record extends for 251 years (A. D. 1745-1996). The results of the glaciochemistry data of the firn core show that the mean concentrations of Cl -, Na + and Mg 2+ are similar to those reported from other coastal areas in East Antarctica. However, mean concentrations of Ca 2+ are much higher than those reported from other regions, this anomaly phenomenon may be related to the strong local terrestrial sources. It is found that the variations of three kinds of sea salt ions (Cl -, Na + and Mg 2+ ) in the past 150 years show very similarly rising trends, which may be the results the Southern Hemisphere warming in the past century.     

Solar radiation transfer in the surface snow layer in Dronning Maud Land,Antarctica

Spectroradiometer measurements of solar radiation (the broadest band used 400–900 nm) were performed above and inside the surface snow layer in western Dronning Maud Land, Antarctica, during the austral summer of 2009–2010. The vertical distributions of transmittance and the extinction coefficient were examined from the surface to a depth of 30 cm. Physical characterization of the snowpack included measurements of thickness, density, hardness (hand test), liquid-water content, and grain size and shape (from photographs of grains). The transmittance was <1% in the upper 20 cm and <27% in the upper 10 cm. The mean spectral diffuse extinction coefficient varied between 0.04 and 0.31 cm^-1 (10–20-cm layer). Using the spectral extinction coefficients of the 0–10-cm and 10–20-cm layers, the depth, where broadband (400–700-nm band) irradiance was 1% of the downwelling irradiance at the surface, was 50 cm. The density of the snow in the upper part of the snowpack (depth of 0–55 cm) varied from 300 to 440 kg m^?3. The predominant grain type was large rounded particles (RGlr) and the predominant grain size was 1 mm.     

Physical properties and stratigraphy of surface snow in western Dronning Maud Land, Antarctica

Information about the spatial variations of snow properties and of annual accumulation on ice sheets is important if we are to understand the results obtained from ice cores, satellite remote sensing data and changes in climate patterns. The layer structure and spatial variations of physical properties of surface snow in western Dronning Maud Land were analysed during the austral summers 1999/2000, 2000/01 and 2003/04 in five different snow zones. The measurements were performed in shallow (1–2 m) snow pits along a transect extending 350 km from the seaward edge of the ice shelf to the polar plateau. These pits covered at least the last annual accumulation and ranged in elevation from near sea level to 2500 m a.s.l. The ع⁸O values and accumulation rates had a good linear correlation with the distance from the coast. The mean accumulation on the ice shelf was 312±28 mm water equivalent (w.e.); in the coastal region it was 215±43 mm w.e. and on the polar plateau it was 92±25 mm w.e. The mean annual conductivity and grain size values decreased exponentially with increasing distance from the ice edge, by 48%/100 km and 18%/100 km respectively. The mean grain size varied between 1.5 and 1.8 mm. Depth hoar layers were a common phenomenon, especially under thin ice crusts, and were associated with low dielectric constant values.     

Mesozoic palaeomagnetism in Vestfjella, Dronning Maud Land, East Antarctica

Summary. Thermal and alternating field demagnetization of oriented samples of Mesozoic lava flows (200–230 Myr) and dykes (154–172Myr) collected from seven nunataks within the Vestfjella region, Dronning Maud Land, revealed stable directions of magnetization of normal and reverse polarity. Directional distributions of both polarities define tight groups along the same palaeomagnetic axis. Depending on whether the regional westward dip of the lava flows originated prior to, or after the intrusive igneous phase, two or one, respectively, palaeomagnetic pole(s) can be estimated. Both poles, however, are in general accord with previous Mesozoic poles from East Antarctica.     

The study on the depositional styles of major ions and the climatic effect of nssSO_4~(2-)in Princess Elizabeth Land, Antarctica

Snow samples collected from a 50 m firn core and two snow pits along the route of the 1996/1997 Chinese First Antarctic Inland Traverse Expedition in Princess Elizabeth Land, East Antarctica, have been analyzed for chemical composition and oxygen isotope ratio. Analyzing the relationship between the concentration and flux of major ions and accumulation rate can draw the following conclusions. 1) The concentrations of major ions in the atmosphere in the study region is big enough so that the concentrations of the ions do not vary with snow accumulation rate, that is to say, the concentrations of major chemical species are independent of snow accumulation rate. 2) The results of analyzing the depositional styles of major chemical species suggest that wet deposition dominates the major ions flux. In addition, there is no apparent correlation between nssSO 2- 4 fluctuations and isotope profile. This would indicate the short-term climatic effect of volcanism is not evident in the region.     

Spatial variability of chemical tracers in surface snow along the traverse route from the coast to 1000 km inland at east Dronning Maud Land, Antarctica

We measured the spatial variability of Cl -, Na +, SO 2- 4, NO - 3 and 7Be concentrations in snow cover along the traverse route from S16 to Dome Fuji station in east Dronning Maud Land, Antarctica. The concentrations of Cl - and Na + at the coast exponentially decreased with distance from the coast up to 200 km inland. Between 200 1000 km inland, the concentrations of Na + were nearly constant. On the other hand, the concentrations of Cl - increased with distance beyond 750 km inland. Furthermore, the contribution factors between Cl - and Na + decreased and the Cl -/Na + ratio and the nssCl -/Cl - ratio increased toward the interior of the continent. These results indicate that sea salt aerosols are transported from the coastal region toward the inland region of the Antarctic continent, and that a source of Cl - other than sea salt exists in the inland plateau of Antarctica. The concentrations of SO 2- 4, NO - 3 and 7Be in snow were relatively high in the coastal region and the inland plateau region compared with those in the katabatic wind region.     

Spatial variations of Pb,As, and Cu in surface snow along the transect from the Zhongshan Station to Dome A,East Antarctica

The spatial distributions of lead, arsenic, and copper(Pb, As, and Cu, respectively) in surface snow along the transect from the Zhongshan Station to Dome A, East Antarctica, are presented. The mean concentrations of Pb, As, and Cu are1.04±1.56 pg/g, 0.39±0.08 pg/g, and 11.2±14.4 pg/g, respectively. It is estimated that anthropogenic contributions are dominant for Pb, As, and Cu. Spatially, Pb concentrations show an exponentially decreasing trend from the coast inland, while a moderate decreasing trend is observed for Cu concentrations in the coastal area(below 2,000 m above sea level(a.s.l.)).In the intermediate area(2,000–3,000 m a.s.l.), the concentrations and enrichment factors of all these elements show high variability due to the complicated characteristics of climate and environment. On the inland plateau(above 3,000 m a.s.l.),the high concentrations of As and Pb are induced by high deposition efficiency, the existence of polar stratospheric precipitation, and the different fraction deposition to East Antarctica. The extremely high concentrations with maximum values of9.59 pg/g and 69.9 pg/g for Pb and Cu, respectively, are suggested to result mainly from local human activities at the station. Our results suggest that source, transport pathway, and deposition pattern, rather than distance from the coast or altitude, lead to the spatial distributions of Pb, As, and Cu; and it is further confirmed by spatial variations of the three metals deposited over the whole continent of Antarctica.     

Annual variations in the meteorological parameters at Jinnah Station，East Antarctica

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Discovery of an ice cave in the Yatude Valley, Langhovde, Dronning Maud Land, East Antarctica

A circular hole was discovered on the downstream side of a glacier dam in the Yatude Valley, Langhovde, East Antarctica, during the 2005–2006 austral summer. The opening of this hole is the first opportunity enabling us to observe the interior of the dam. The opening led to a large cave in the dam, raising the possibility of meltwater drainage through the dam. The Yatude Valley is an approximately U-shaped fluvial valley. The valley floor has been incised to form a box-shaped inner valley that contains fluvial terraces and large boulders upon the valley floor. The origin of these features can be explained by a large amount of running water; however, we consider it unlikely that a regular current has flowed through this site for a long period. Instead, it is more likely that large quantities of lake water have been periodically discharged due to collapse of the glacier dam or spilling out through a tunnel channel within the cave. The discovered hole and the ice cave are key features in understanding the historical development of the Yatude Valley in relation to the melting history of the Antarctic ice sheet.     

热烈的祝贺(发刊词)

《南极研究》与广大读者见面了.我怀着十分高兴的心情为它的创刊致以热烈的祝贺!我国的南极考察工作起步较晚,但发展较快,尤其是近几年,建成了南极长城站,已在长城站地区进行了三次较大规模的多学科考察,初步取得了可喜的成果.我国已经具备了独立开展南极考察的能力,并取得了一些经验.这些成绩是在党中央、国务院的关怀和支持下取得的,     

Use of NOAA-AVHRR data to monitor snow cover and spring meltoff in the wildlife habitats in Jameson Land, East Greenland

NOAA-AVHRR satellite data have been used for a multi-year analysis of the seasonal variation of snow cover on the peninsula of Jameson Land located from 70°30'N to 72°N on the eastern coast of Greenland. Monitoring programmes for muskoxen and geese populations in Jameson Land wert started in the early 1980s to assess the impact of oil exploration in the area. This study was conducted to provide snow cover data to the wildlife monitoring programmes because snow cover is an important factor which can affect the numbers and distribution of muskoxen and other wildlife in the area.
Snow cover mapping is based on the geometric correction and radiometric calibration of each satellite scene before the visual bands are corrected for the terrain-effects and high solar zenith angle by using a simple radiation model. The atmospheric effect on the thermal infrared bands is corrected by using the "split-window" method. An automatic filtering routine with empirically determined thresholds is used to determine cloud-and haze-covered areas before the snow cover is computed from a linear expression using albedos of bare ground and full snow cover. By combining the satellite information with ground measurements and a digital terrain model, both the spatial distribution of snow cover and the total snow cover depletion can be obtained.
The method makes it possible to analyse the variation in regional and seasonal snow cover in wildlife habitats. The variation in snow cover depletion has been analysed in five subareas in the muskox area, and the results indicate that the snow cover pattern is an important factor which influences muskox calf crop and regional distribution of the muskox population. The method has proved useful for monitoring the duration of snow cover, and its application ought to facilitate the future study of wildlife habitats in extensive alpine and arctic areas.     

The establishment of GPS network in Grove Mountains,East Antarctica

The Grove Mountains are located in Princess Elizabeth Land,East Antarctica,ext ending from 72° to 73°S latitude and 73° to 76°E longitude,covering approxi mately 8000 km～2 areas.During the 2002/2003 austral summer season,the 19th CH INARE(Chinese National Antarctic Research Expedition)carried out the third expedition in Grove Mountains,East Antarctica.The Geodetic network was establ ished,which can provide ground control for the satellite image map for the mult i-discipline expedition in the Grove Mountains where seven permanent GPS benchm a rks were set up supported by the helicopter and snow vehicles.All GPS sites bes ides Z001 were observed at least for one hour using the dual frequencies Trimble 4000ssi GPS receivers.The data were processed by the comprehensive GPS analysi s package—GAMIT/GLOBK and the precision is good enough to satisfy with the acqu irement of satellite mapping in this area.     

Interpretation of the GRACE-derived mass trend in Enderby Land, Antarctica

Monthly gravity solutions of the Gravity Recovery and Climate Experiment (GRACE) reveal three areas in Antarctica with striking interannual mass trends. The positive mass trend in Enderby Land, East Antarctica, is poorly understood because of uncertainties in the surface ice-sheet mass balance, post-glacial rebound (PGR), and processing of GRACE data. In this study, we compare the GRACE mass trends with values estimated from in situ snow-stake measurements, and Ice Cloud and land Elevation Satellite (ICESat) data. The mass trends estimated from ICESat data show a strong correlation with GRACE mass trends. In contrast, the snow-stake data show discrepancies with temporal variations in GRACE mass, especially in 2006. The discrepancies are probably associated with basal ice-sheet outflow, which is difficult to observe using snow stakes. We conclude that the bulk of the GRACE mass trend can be explained by snow accumulation and basal ice-sheet outflow.