In Ammassalik, in southeast Greenland, downslope winds can reach hurricane intensity and represent a hazard for the local population and environment. They advect cold air down the ice sheet and over the Irminger Sea, where they drive large ocean–atmosphere heat fluxes over an important ocean convection region. Earlier studies have found them to be associated with a strong katabatic acceleration over the steep coastal slopes, flow convergence inside the valley of Ammassalik, and—in one instance—mountain wave breaking. Yet, for the general occurrence of strong downslope wind events, the importance of mesoscale processes is largely unknown. Here, two wind events—one weak and one strong—are simulated with the atmospheric Weather Research and Forecasting (WRF) Model with different model and topography resolutions, ranging from 1.67 to 60 km. For both events, but especially for the strong one, it is found that lower resolutions underestimate the wind speed because they misrepresent the steepness of the topography and do not account for the underlying wave dynamics. If a 5-km model instead of a 60-km model resolution in Ammassalik is used, the flow associated with the strong wind event is faster by up to 20 m s−1. The effects extend far downstream over the Irminger Sea, resulting in a diverging spatial distribution and temporal evolution of the heat fluxes. Local differences in the heat fluxes amount to 20%, with potential implications for ocean convection.
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机译：在格陵兰岛东南部的阿玛萨里克（Ammassalik），下坡风可能达到飓风强度，对当地人口和环境构成危害。他们使冰冷的空气顺着冰盖向下流经艾明格海，在艾明格海中推动重要的海洋对流区域上较大的海洋-大气热通量。较早的研究发现，它们与陡峭的沿海斜坡上强烈的katabatic加速，Ammassalik山谷内部的水流汇聚以及（有时）山波破碎有关。然而，对于普遍发生的强下坡风事件，中尺度过程的重要性基本上是未知的。在此，使用具有不同模型和地形分辨率（范围从1.67到60 km）的大气天气研究与预报（WRF）模型，模拟了两种风事件（一弱风和一强风）。对于这两种事件，特别是对于强事件，发现较低的分辨率会低估风速，因为它们不能正确反映地形的陡度，并且不能说明潜在的波浪动力学。如果使用5 km模型而不是Ammassalik中的60 km模型分辨率，则与强风事件相关的流量将加快20 m s-1。这些影响延伸至艾明格海的下游，导致空间分布和热通量随时间变化。热通量的局部差异达20％，可能对海洋对流产生影响。
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