Modeling the Mechanisms for the Formation and Maintenance of the Weddell Polynya

本文提出的工作涉及一个区域耦合环流模型的开发和应用，目的是阐明威德尔冰海（威德尔海冬季海冰覆盖范围内的大片开放水域）的启动、维持和终止机制。在卫星无源微波图像中可以明显地看到这个冰湖，从1974年到1976年，它的高度超过了25万平方公里。将在本研究中使用的完全关联模式由大气行星边界层模式、包含积雪影响的海冰模式和三维海洋环流模式组成。一个通量耦合器通过传递能量、质量和动量的相关通量来连接三个模型。多冰湖的精细尺度特征将在模型的高分辨率版本上建模，该模型将嵌套在其大尺度域版本的低分辨率网格中。威德尔冰海的基本形成机制被认为是暖深水（WDW）从其南极环极流的源头被带入威德尔海。通常情况下，这种温暖的水（只有在南极的标准下才是温暖的：它的温度在0到+1摄氏度之间）被一种更冷但含盐量更少（因此更轻）的威德尔冬水表层保持在大约300米的深度以下。据推测，这种情况偶尔会破裂；大气/海洋动力学除去了寒冷的表层，使WDW不仅融化了现有的冰，而且阻止了新冰的形成。最终，WDW热储耗尽，冷表面层重新建立。本研究的预期结果不仅可以定量确定多冰湖的特征时间演化，还可以定量确定多冰湖的特征重现间隔、空间尺度以及与威德尔海海底地形的联系。它是一种区域性气候事件，通过影响世界海洋深处和底部水的形成和分布速率而具有全球性后果。

This proposed work concerns the development and application of a regional coupled general circulation model for the purpose of elucidating the mechanisms that initiate, maintain, and terminate the Weddell Polynya - a large area of open water within the winter sea ice cover of the Weddell Sea. This polynya was prominently seen in satellite-based passive microwave imagery, and at it height, from 1974 to 1976, exceeded 250,000 square kilometers in size.The fully linked model that will be used in this study is composed of an atmospheric planetary boundary layer model, a sea ice model that includes the effects of a snow cover, and a three dimensional ocean general circulation model. A flux coupler connects the three models by passing the relevant fluxes of energy, mass, and momentum among them. The fine-scale features of the polynya will be modeled on a high resolution version of the models that will be nested within the lower resolution grid of their large-scale domain versions.The basic initiating mechanism of the Weddell Polynya is thought to be the surfacing of Warm Deep Water (WDW) which is entrained into the Weddell Sea from its origins within the Antarctic Circumpolar Current. Normally this warm water (which is warm only by antarctic standards: its temperature is between 0 and +1 deg Centigrade) is kept below depth of about 300 meters by a colder but less saline (hence lighter) surface layer of Weddell Winter Water. Occasionally, it is speculated, this condition breaks down; the atmosphere/ocean dynamics remove the cold surface layer and allow the WDW not only to melt the existing ice, but keep new ice from forming. Eventually the WDW heat reservoir is exhausted and a cold surface layer is reestablished. The expected results of this study are a quantitative determination not only of the characteristic time evolution of the polynya, but also its characteristic recurrence interval, spatial scale, and its connection to the bottom topography of the Weddell Sea. It is a regional climatic event that has global consequences by affecting the formation and distribution rate of deep and bottom water thought the world ocean.