Basal melting of A-38B: A physical model constrained by satellite observations
Basal melting of A-38B: A physical model constrained by satellite observations
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DOI：
10.1016/j.rse.2007.03.022
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发表时间：
2007-11-30
影响因子：
13.5
通讯作者：
Rack, Wolfgang
中科院分区：
文献类型：
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作者：
Jansen, Daniela;Schodlok, Michael;Rack, Wolfgang
我们观察了大型平板冰山A-38 B的时间段内，从1998年在伦讷李架的产犊事件，直到2004年在南格鲁吉亚附近的接地通过各种星载传感器。最初的冰厚是由雷达测高仪确定的，冰山的形状是由雷达成像和光学仪器确定的。在漂移的不同阶段的干舷变化来自ICESat激光高度计剖面。卫星资料的分析证实，A-38 B的衰变主要受基底侵蚀的控制。然后，我们使用了一个数值模型来模拟冰山融化，并通过改变温度（伽马（T））和盐（伽马（S））的湍流交换参数来匹配ICESat数据所获得的结果来拟合融化速率。结果表明，该冰山经历了以冰山漂移速度为特征的三种融化状态：（1）威德尔海的融化条件与强潮流下的冰架情况相似，对应于伽玛（T）为1.0 × 10 ~（-4）m·s ~（-1）。(2)在斯科舍海，冰山随洋流不受阻碍地漂移，并被其自身的融水所包围，伽马（T）为0.4 * 10（-4）m s（-1）。(3)在搁浅位置处，由于潮汐流的影响，摩擦速度又很高，伽马（T）为1.8 * 10（-4）m s（-1）。在所有情况下，gamma（s）设置为0.00505 gamma（T）。分析表明，ICESat GLAS数据与卫星图像一起可以提供更好的湍流交换参数的估计，这是一个进步，提高知识的淡水输入融化冰山到南大洋。(c)2007年爱思唯尔公司All rights reserved.
We observed the large tabular iceberg A-38B in the time period from the calving event at the Ronne lee Shelf in 1998 until its grounding near South Georgia in 2004 by means of various space-borne sensors. The initial ice thickness was determined by radar altimetry, the iceberg shape from radar imaging and optical instruments. The freeboard change at different stages of the drift was derived from ICESat Laser altimeter profiles. The analysis of the satellite data confirms that the decay of A-38B is governed mainly by basal erosion. We then used a numerical model for simulating iceberg melting and fitted the melt rate by varying the turbulent exchange parameters for temperature (gamma(T)) and salt (gamma(s)) to match the results obtained by ICESat data. Our results show that the iceberg passed through three melting regimes characterized by iceberg drift velocity: (1) In the Weddell Sea melting conditions are similar to the situation under an ice shelf with strong tidal currents which corresponds to a gamma(T) Of 1.0 * 10(-4) m s(-1). (2) In the Scotia Sea, where the iceberg drifts unhindered with the ocean current and is surrounded by its own melt water, gamma(T,) is 0.4 * 10(-4) m s(-1). (3) At the grounding position friction velocity is again high due to tidal currents and gamma(T) is 1.8 * 10(-4) m s(-1). gamma(s) is set to 0.00505 gamma(T) in all cases. The analysis shows that ICESat GLAS data together with satellite imagery can provide better estimates of turbulent exchange parameters, which is a step forward in improving the knowledge of fresh water input from melting icebergs into the Southern Ocean. (c) 2007 Elsevier Inc. All rights reserved.