The effects of precipitation and river runoff in a coupled ice-ocean model of the Arctic
The effects of precipitation and river runoff in a coupled ice-ocean model of the Arctic
复制标题
北极冰海耦合模型中降水和河流径流的影响
DOI：
10.1007/s003820050143
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发表时间：
1996
期刊：
影响因子：
4.6
通讯作者：
J. Walsh
中科院分区：
文献类型：
--
作者：
J. Weatherly;J. Walsh
为了研究降水和河流径流对海冰的影响，建立了一个北极冰-海耦合模式。动力-热力学海冰模式与海洋环流模式相耦合，该模式包括垂直混合的湍流闭合方案。该模型受1980-1989年年际变化的大气温度和气压资料以及空间变化的月平均降水量和河流径流的影响。计算了冰的生长、积雪融化、降雨和径流对海洋的盐度和淡水通量，没有对海洋盐度的人为限制。模拟的冰层厚度与观测到的模式相似，加拿大群岛全年都是最厚的冰层。模拟的冰漂移再现了穿过弗拉姆海峡的波弗特环流和跨极漂移。由垂直混合方案产生的稳定的北极盐跃层将表层与大西洋层隔离开来，并降低了垂直热量和盐度通量。对于盐跃层减弱所产生的更大的海洋热通量，零降水的敏感性实验导致冰厚度迅速减小，而双倍降水的实验则导致冰厚度的较小增加。由于模型中径流输运的年代际时间尺度，零径流实验的结果比零降水情况下冰层厚度的减少要慢。结果表明，由人为或自然气候变化引起的北极降水和河流径流的年代际趋势有可能对北极海冰状况产生广泛的影响。
A coupled ice-ocean model of the Arctic is developed in order to study the effects of precipitation and river runoff on sea ice. A dynamic-thermodynamic sea ice model is coupled to an ocean general circulation model which includes a turbulent closure scheme for vertical mixing. The model is forced by interannually varying atmospheric temperature and pressure data from 1980–1989, and spatially varying mean monthly precipitation and river runoffs. Salinity and fresh water fluxes to the ocean from ice growth, snow melt, rain, and runoffs are computed, with no artificial constraints on the ocean salinity. The modeled ice thickness is similar to the observed pattern, with the thickest ice remaining against the Canadian Archipelago throughout the year. The modeled ice drift reproduces the Beaufort gyre and Transpolar drift exiting through Fram Strait. The stable arctic halocline produced by the vertical mixing scheme isolates the surface from the Atlantic layer and reduces the vertical fluxes of heat and salinity. A sensitivity experiment with zero precipitation results in rapidly decreasing ice thickness, in response to greater ocean heat flux from a weakening of the halocline, while an experiment with doubled precipitation results in a smaller increase in ice thickness. A zero-runoff experiment results in a slower decrease in ice thickness than the zero-precipitation case, due to the decadal time scale of the transport of runoff in the model. The results suggest that decadal trends in both arctic precipitation and river runoffs, caused either by anthropogenic or natural climatic change, have the potential to exert broad-scale impacts on the arctic sea ice regime.