The Antarctic drainage flow: implications for hemispheric flow on the Southern Hemisphere
The Antarctic drainage flow: implications for hemispheric flow on the Southern Hemisphere
复制标题
南极排水流：对南半球半球流的影响
作者：
I. N. James
据报道，埃克曼对倾斜冰面上的地表排水风进行了分析。边界层的埃克曼抽吸导致冰盖顶部上方对流层上层气旋涡旋的形成。上层涡度的强度和分布取决于底层冰盖的形状。通过与轴对称冰盖上方流动的多级原始方程模型的结果进行比较，验证了计算结果。两个模型都预测地表排水流将在几天的时间内消失，而上部涡流预计将比观测到的强得多。讨论了可能导致上层涡度消耗并因此导致大量排水流保留的各种机制。结论是，衰减的中纬度气旋对极地涡旋的破坏以及随后将气旋涡量输出到低纬度地区是最可能的机制。
An Ekman analysis of the surface drainage winds over a sloping ice surface is reported. Ekman pumping by the boundary layer leads to the formation of an upper tropospheric cyclonic vortex above the summit of the ice sheet. The strength and distribution of upper level vorticity is determined by the shape of the underlying ice sheet. The calculation is verified by comparison with the results from a multi-level primitive equation model of flow above an axisymmetric ice sheet. Both models predict that the surface drainage flow will die out on a timescale of a few days, while the upper vortex is predicted to be considerably stronger than observed. Various mechanisms which could lead to the depletion of upper level vorticity, and hence to the retention of a substantial drainage flow, are discussed. It is concluded that disruption of the polar vortex by decaying mid-latitude cyclones, and the consequent export of cyclonic vorticity to lower latitudes, is the most probable mechanism.