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Sea ice / ocean coupled system in the melting season for seasonal ice zones

季节性冰区融化季节的海冰/海洋耦合系统

基本信息

批准号：
09640516
负责人：
OHSHIMA Keiichirou
金额：
$ 1.79万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640516/
关键词：
melting of sea ice heat budget shortwave radiation ice ocean coupled model ice albedo feedback Antarctic Ocean microwave radiometer ocean mixed layer 季節海氷域アイスアルベドフィールドバック熱交換係数海氷海氷-海洋相互作用 SSM I

项目摘要

The heat budget analyses show that the net heat input at the water surface reaches 1OO-150 W m^<-2> in the active ice melting season due to large solar heating, while that at the ice surface is nearly zero because of the difference in surface albedo. The temporal variation of the heat input to the upper ocean corresponds well to the melting rate of sea ice. These results suggest that melting of sea ice in the Antarctic Ocean is mostly accomplished by the heat input to the upper ocean through the open water area.In the Antarctic Ocean, the anomalies in ice concentration in the retreat season are highly correlated with those in the next advance season. In the retreat season, net heat input into the upper ocean from the atmosphere is maximum and is mainly determined by ice concentration. We suggested that the anomaly in the heat input is memorized in the ocean and then affects the next advance of sea ice. This positive feedback can partly explain the interannual variation of the sea ice cover.We propose a simple ice upper ocean coupled model in which sea ice melts only by the ocean heat supplied from the air. The model shows that the relation between ice concentration and upper ocean temperature converges to a certain asymptotic curve with time, which well explains the observations in the Antarctic summer. The model also roughly reproduces meridional retreat of the Antarctic sea ice. The model can describe the following ice albedo feedback effect ; once the ice concentration is decreased by the divergent wind field, the heat input to the upper ocean is enhanced, leading to further decrease of ice concentration. This mechanism can partly explain the year to year variation of the sea ice retreat.

热量收支分析表明，在融冰活跃季节，由于太阳辐射的强烈加热，水面的净热量输入可达100 ~ 150 W·m ~（-1<-2>），而由于表面辐射的差异，冰面的净热量输入几乎为零。海洋上层热量输入的时间变化与海冰的融化速率相对应。这些结果表明，南极海冰的融化主要是通过开放水域向上层海洋输入热量完成的，在南极冰密集度的退季异常与下一个进季异常有很强的相关性。在退冰季节，从大气向上层海洋输入的净热量最大，主要由冰浓度决定。我们认为，在热输入的异常是记忆在海洋中，然后影响海冰的下一个前进。这种正反馈可以部分地解释海冰覆盖的年际变化。我们提出了一个简单的冰-上层海洋耦合模式，其中海冰融化仅依靠来自空气的海洋热量。该模式表明，海冰密集度与上层海洋温度的关系随时间收敛于一定的渐近曲线，很好地解释了南极夏季的观测结果。该模型还大致再现了南极海冰的纬向退缩。该模式可以描述冰浓度随辐散风场变化的反馈效应，一旦辐散风场使冰浓度降低，则向上层海洋的热量输入增加，导致冰浓度进一步降低。这一机制可以部分解释海冰退缩的年际变化。