The distribution and formative processes of latent-heat polynyas in East Antarctica
The distribution and formative processes of latent-heat polynyas in East Antarctica
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DOI：
10.3189/1998aog27-1-420-426
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发表时间：
1998
影响因子：
2.9
通讯作者：
R. Massom;P. Harris;K. Michael;M. Potter
中科院分区：
文献类型：
--
作者：
R. Massom;P. Harris;K. Michael;M. Potter
利用1987年7月至1994年8月期间特殊传感器微波/成像仪数据得出的海冰密集度，对东南极洲浅水区（冰间湖）的特征进行了研究。浅水区的面积被定义为海冰密集度≤75%。分析显示，研究区域内共有28个沿海浅水区。对面积范围的时空变化进行了量化。平均最大面积范围出现的时间从6月到10月不等。对每个浅水区的水深和风向进行了研究，以评估这些参数在浅水区形成和维持过程中的相对重要性。在20个地点，浅滩和沙洲形成了冰山的搁浅区和固定冰的锚定地点，对浮冰主要向西的漂移形成了障碍；在其他地方，南北向的海岸突出部分或排列形成了类似的障碍。随后，下降风和气旋风将新形成的海冰从这些障碍的背风处吹走，维持了海冰密集度较低和开阔水域的区域。很少有沿海浅水区完全归因于下降风的流出。水深、地形和风向的综合影响是大多数浅水区特征的原因。许多浅水区被认为是边缘性的，其特点是海冰密集度偶尔会降至75%以下。对海冰密集度<75%的区域的冬季年度总面积的分析表明，1987 - 1994年期间浅水区总面积没有趋势。帝企鹅（Aptenodytes forsteri）栖息地的已知位置也被发现与沿海浅水区的位置有关。
A study of polynya characteristics in East Antarctica was undertaken using ice concentrations derived from special sensor microwave/imager data for the period July 1987-August 1994. The areas of polynyas were defined as having an ice concentration ≤75%. The analysis revealed a total of 28 coastal polynyas within the study region. The spatial and temporal variability in areal extent was quantified. The timing of mean maximum areal extent varied from June to October. The bathymetry and wind regime at each polynya site was examined to gauge the relative importance of these parameters in polynya formation and maintenance. In 20 locations, shallow banks and shoals form grounding zones for icebergs and anchoring sites for fast ice, which form barriers to the predominantly westward drift of the pack ice; elsewhere north-south coastal protrusions or alignments form similar barriers. The subsequent removal of newly formed sea ice from the lee of such barriers by katabatic and synoptic winds maintains areas of reduced ice concentration and open water. Very few coastal polynyas are attributed solely to katabatic outflow. The combined influence of bathymetry, topography and winds is responsible for the characteristics of the majority of polynyas. Many were considered to be marginal, characterised by occasional periods when the ice concentration falls below 75%. An analysis of annual winter totals of areas with ice concentrations < 75% shows no trends in total polynya areal extent over the period 1987-94. Known locations of emperor penguin (Aptenodytes forsteri) rookeries were also found to be associated with the locations of coastal polynyas.