The Basic Ingredients of the North Atlantic Storm Track. Part II: Sea Surface Temperatures
The Basic Ingredients of the North Atlantic Storm Track. Part II: Sea Surface Temperatures
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DOI：
10.1175/2011jas3674.1
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发表时间：
2011-08-01
影响因子：
3.1
通讯作者：
Blackburn, Michael
中科院分区：
文献类型：
--
作者：
Brayshaw, David James;Hoskins, Brian;Blackburn, Michael
利用英国气象局统一模式（HadCM3）的第三个气候配置的大气分量（HadAM3）中的理想（水行星）和“半现实”边界条件的GCM模拟层次，研究了北大西洋海温模式对风暴路径的影响。这一框架使确定对流层对北大西洋海温型的响应机制既可以单独研究，也可以与大陆尺度的陆块和地形学结合研究。孤立地说，“墨西哥湾流”海温模式加强了下游风暴路径，而“北大西洋暖流”海温模式减弱了下游风暴路径。这些变化与温带海温梯度和近地面斜压性的变化一致，每一次风暴路径响应都与对流层急流结构的一致变化有关。在海温梯度增强的暖侧发现局地近地面水平风辐合增强，与上升空气和降水增加有关，与以往研究一致。将组合海温型引入半现实框架（包括“北美”大陆和“落基山脉”）后，结果表明，地形导致的北大西洋风暴路径西南-东北倾斜增强。特别是，墨西哥湾流使西大西洋的风暴路径南移，而东北大西洋强烈的高纬海温梯度则增强了那里的风暴路径。
The impact of North Atlantic SST patterns on the storm track is investigated using a hierarchy of GCM simulations using idealized (aquaplanet) and "semirealistic" boundary conditions in the atmospheric component (HadAM3) of the third climate configuration of the Met Office Unified Model (HadCM3). This framework enables the mechanisms determining the tropospheric response to North Atlantic SST patterns to be examined, both in isolation and in combination with continental-scale landmasses and orography.In isolation, a "Gulf Stream" SST pattern acts to strengthen the downstream storm track while a "North Atlantic Drift" SST pattern weakens it. These changes are consistent with changes in the extratropical SST gradient and near-surface baroclinicity, and each storm-track response is associated with a consistent change in the tropospheric jet structure. Locally enhanced near-surface horizontal wind convergence is found over the warm side of strengthened SST gradients associated with ascending air and increased precipitation, consistent with previous studies.When the combined SST pattern is introduced into the semirealistic framework (including the "North American" continent and the "Rocky Mountains"), the results suggest that the topographically generated southwest-northeast tilt in the North Atlantic storm track is enhanced. In particular, the Gulf Stream shifts the storm track south in the western Atlantic whereas the strong high-latitude SST gradient in the northeastern Atlantic enhances the storm track there.