南大洋冰山特征初步分析

Preliminary analysis of iceberg characteristics in the Antarctic Ocean

基于中国第19次南极科学考察从2002年12月至2003年1月在南大洋航行期间利用船舶雷达对航线两侧冰山的观测,给出了从雷达图像中获取冰山尺寸及其运动速度、方向的方法,获得了航线周围冰山的运动速度和尺寸分布.通过比较分析发现R oss海和W edde ll海冰山长度主要集中在880 m和1 180 m左右,冰山运动主要呈东北或西北向,运动速度与北极冰山的速度接近;P rydz湾的最大冰山尺寸则在65.4°S^68.2°S内随着接近Am ery冰架先增大后减小,符合一般物体崩塌的力学规律.另外,通过多元回归分析建立了冰山运动速度和同步测量的风速、流速间的关系,发现在当地典型情况下,风速对冰山运动的贡献是流速贡献的一半.

Based on iceberg observations by using the marine radar when shipping in the Antarctic Ocean from Dec. 2002 to Jan. 2003 during the 19th Chinese National Antarctic Research Expedition, a method to acquire iceberg size and drift velocity from radar imagery is presented and iceberg size and velocity distribution along the investigation route are obtained consequently. The result reveals that the modal values of iceberg length in Ross Sea and Weddell Sea are 880 m and 1 180 m respectively; iceberg drifts here are mainly north-eastward or north-westward and drift velocities are similar to those of Arctic iceberg. And the max-iceberg length in Prydz Bay increases and then decreases as closing Amery Ice Shelf in the latitude range of 65.4°S - 68.2°S, which accords with the mechanics rule of object failing. Moreover, a kinematic relationship of iceberg drift with synchronous measured wind and current velocities is developed by multiple linear regressions, and the result indicates that the contribution of the wind to iceberg drift is half of that of current velocity under local typical conditions.