25 August 2011, Volume 22 Issue 3
    

  • Select all
    |
    Contents
  • Editorial Office of Advances in Polar Science
    Advances in Polar Science. 2011, 22(3): 0-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
  • JIANG Shan,LIU XiaoDong *,XU LiQiang,SUN LiGuang
    Advances in Polar Science. 2011, 22(3): 131-142. https://doi.org/10.3724/SP.J.1085.2011.00131
    Abstract ( ) Download PDF ( ) Knowledge map Save

    We collected two lake sediment cores (MC and DM) from the East Antarctic region for analysis of biogenic silica and other biogeochemical parameters (e.g., organic matter, C, N, S, H). Based on synthetically comparative research, we focused on the potential application of biogenic silica (BSi) for the reconstruction of paleo-primary productivity in the East Antarctic lakes. Analytical results showed that a large number of diatoms were well preserved in the freshwater lake sediments, and that concentrations of biogenic silica displayed notable flctuations over diffrent water depths. The content of biogenic silica had a consistent profie over water depth, and this pattern changed with organic matter, reflcting their potential as eco-environmental proxies. Low levels of BSi and organic matter indicated reduction of lake algal production, and corresponded to decreased lake primary productivity. Due to the fragile ecosystem state and limited contribution of terrestrial organic matter in the East Antarctic lakes, the contents of biogenic silica in the lacustrine sediments can sensitively indicate the evolutionary history of paleo-primary productivity. Overall, BSi is an ideal proxy for the reconstruction of past eco-environmental change recorded in the lacustrine sediments on East Antarctica.

  • LEI RuiBo *; 1,LI ZhiJun 2,ZHANG ZhanHai 1,CHENG YanFeng 1
    Advances in Polar Science. 2011, 22(3): 143-152. https://doi.org/10.3724/SP.J.1085.2011.00143
    Abstract ( ) Download PDF ( ) Knowledge map Save

    Thermodynamic processes of ice in three lakes and landfast ice around Zhongshan Station, Antarc- tica, were observed in 2006. The mass balance of lake ice was compared with that of landfast ice. The responses of lake ice and sea ice temperatures to the local surface air temperature are explored. Vertical conductive heat fluxes at varying depths of lake ice and sea ice were derived from vertical temperature profiles. The freeze up of lake ice and landfast ice occurred from late February to early March. Maximum lake ice thicknesses occurred from late September to early October, with values of 156–177 cm. The maximum sea ice thicknesses of 167–174 cm occurred relatively later, from late October to late November. Temporal variations of lake ice and landfast ice internal temperatures lagged those of air temperatures. High-frequency variations of air temperature were evidently attenuated by ice cover. The temporal lag and the high-frequency attenuation were greater for sea ice than for lake ice, and more distinct for the deeper ice layer than for the upper ice layer. This induced a smaller conductive heat flux through sea ice than lake ice, at the same depth and under the same atmospheric forcing, and a smoother fluctuation in the conductive heat flux for the deeper ice layer than for the upper ice layer. Enhanced desalination during the melt season increased the melting point temperature within sea ice, making it different from fresh lake ice.

  • GUO GuiJun 1; 2,SHI JiuXin *; 1; 2,ZHAO JinPing 1; 2,JIAO YuTian 1; 2,XU Dong 1; 2
    Advances in Polar Science. 2011, 22(3): 153-164. https://doi.org/10.3724/SP.J.1085.2011.00153
    Abstract ( ) Download PDF ( ) Knowledge map Save

    Freshwater content (FWC) in the Arctic Ocean has changed rapidly in recent years, in response to significant decreases in sea ice extent. Research on freshwater content variability in the Canada Basin, the main storage area of fresh water is very important to understand the input-output freshwater in the Arctic Ocean. The FWC in the Canada Basin was calculated using data from the Chinese National Arctic Research Expeditions of 2003 and 2008, and from expeditions of the Canadian icebreaker Louis S. St-Laurent (LSSL) from 2004 to 2007. Results show that the upper ocean in the Canada Basin became continuously fresher from 2003 to 2008, except during 2006. The FWC increased at a rate of more than 1 m•a−1, and the maximum increase, 7 m, was in the central basin compared between 2003 and 2008. Variability of the FWC was almost entirely limited to the layer above the winter Bering Sea Water (wBSW), below which the FWC remained around 3 m during the study period. Contributors to the FWC increase are generally considered to be net precipitation, runoff changes, Pacific water inflow through the Bering Strait, sea ice extent, and the Arctic Oscillation(AO). However, we determined that the first three contributors did not have apparent impact on the FWC changes. Therefore, this paper focuses on analysis of the latter two factors and the results indicate that they were the major contributors to the FWC variability in the basin.

  • XU GuoJie 1; 2,CHEN LiQi 1; 2,ZHANG YuanHui 1; 2,WANG JianJun 1; 2,LI Wei 1; 2,LIN Qi 1; 2
    Advances in Polar Science. 2011, 22(3): 165-174. https://doi.org/10.3724/SP.J.1085.2011.00165
    Abstract ( ) Download PDF ( ) Knowledge map Save

    The ionic compositions of aerosol samples collected during the 26th Chinese National Antarctic Re- search Expedition were analyzed and the sources of ions were distinguished. Cl- Na+, SO42- , NO3- , and Mg2+were the most abundant ionic components in the marine aerosols. Cl-and Na+ contributed over 70% in the total ionic composition, indicating the sea salt is still the primary composition in marine aerosols, followed by the sulfate as the secondary ionic component existed as NH4NO3, NH4HSO4, (NH4)2SO4. The maximal sea salt concentrations were found at around 40°S and could be attributed to greater winds. The concentrations of methane sulfonic acid (MSA) appeared increasing trend from the low to high latitudes, possibly caused by lower temperature in air and higher marine biological processes in the marginal waters in Antarctica. The correlation and factor analyzes were used to investigate possible sources of these ions. Cl- Br- Na+, K+, Mg2+ and Ca2+ had predominantly marine sources; while F- NO3- and NH4+ had mostly anthropogenic sources; MSA had marine biogenic sources. The concentrations of SO42- were inflenced by both marine and anthropogenic sources.

  • HE Fang *;1,ZHANG BeiChen 1,Joran Moen 2,HUANG DeHong 1
    Advances in Polar Science. 2011, 22(3): 175-183. https://doi.org/10.3724/SP.J.1085.2011.00175
    Abstract ( ) Download PDF ( ) Knowledge map Save

    Long-duration conjugate observations by the EISCAT Svalbard Radar (ESR) and the ionosonde at Zhongshan station from the International Polar Year (IPY) during solar minimum conditions are analyzed, with respect to variability in the F2-layer peak parameters. A comparison between International Reference Ionosphere- 2007 (IRI-2007) and observation data clearly demonstrates good agreement in summer, but greater deviations in winter. The IRI model reproduces the F2 peak parameters dominated by solar photoionization reasonably well, but it does not address the effect of electron precipitation. Hence, the discrepancies become large in the winter auroral ionosphere.

  • WANG Qian 1,MENG QingHu 1,HU ZeJun *; 2,XING ZanYang 2; 3,LIANG JiMin *; 1,& HU HongQiao 2
    Advances in Polar Science. 2011, 22(3): 184-191. https://doi.org/10.3724/SP.J.1085.2011.00184
    Abstract ( ) Download PDF ( ) Knowledge map Save

    Based on the fuzzy local information c-means (FLICM) clustering algorithm, a new method is developed for extracting the equatorward and poleward boundaries of the auroral oval from images acquired by the Ultraviolet Imager (UVI) aboard the POLAR satellite. First, the method iteratively segments the UVI image with the FLICM clustering algorithm, according to an integrity criterion for the segmented auroral oval. Then, possible gaps in the extracted auroral oval are filled, based on prior knowledge of its shape. To evaluate the method objectively, the extracted boundaries are compared with the precipitating electron boundaries determined from DMSP satellite precipitation particle data. The evaluation results demonstrate that the proposed method generates more accurate auroral boundaries than traditional methods.

  • ZHANG ZhiHua *; 1,& John C Moore *; 2; 3; 4
    Advances in Polar Science. 2011, 22(3): 192-198. https://doi.org/10.3724/SP.J.1085.2011.00192
    Abstract ( ) Download PDF ( ) Knowledge map Save

    When one applies the wavelet transform to analyze finite-length time series, discontinuities at the data boundaries will distort its wavelet power spectrum in some regions which are defined as a wavelength-dependent cone of influence (COI). In the COI, significance tests are unreliable. At the same time, as many time series are short and noisy, the COI is a serious limitation in wavelet analysis of time series. In this paper, we will give a method to reduce boundary effects and discover significant frequencies in the COI. After that, we will apply our method to analyze Greenland winter temperature and Baltic sea ice. The new method makes use of line removal and odd extension of the time series. This causes the derivative of the series to be continuous (unlike the case for other padding methods). This will give the most reasonable padding methodology if the time series being analyzed has red noise characteristics.

  • WANG ZeMin *,AI SongTao,ZHANG ShengKai,& DU YuJun
    Advances in Polar Science. 2011, 22(3): 199-204. https://doi.org/10.3724/SP.J.1085.2011.00199
    Abstract ( ) Download PDF ( ) Knowledge map Save

    A majority of the exposed nunataks located in the Grove Mountains of the Antarctic interior have yet to have had their elevations measured. The elevations of Mason Peak and Wilson Ridge were precisely determined by the Grove Team of the 26th CHINARE in 2010, with Mason Peak turning out to be the highest of the Grove Mountains. Considering that both Mason Peak and Wilson Ridge are difficult to climb because of their cragginess, we first selected three control points on the ice surface near Mason Peak and positioned them with GPS. Thus, accurate elevations of Mason Peak and Wilson Ridge could be calculated from three directions using forward intersection and trigonometric leveling of a high-precision theodolite at the chosen control points. The results provide basic geodetic information that can be referred to as high-precision control points for surveying and mapping in this part of Antarctica. This paper elaborates on the process of measurement and computation of the mountains summit elevations, and also analyzes the details of the principal elements influencing the accuracy of trigonometric leveling, the determination of refraction coefficients k, and observations of structure and distance.