Small-Scale Variability in the Coastal Atmospheric Boundary Layer
Small-Scale Variability in the Coastal Atmospheric Boundary Layer
复制标题
沿海大气边界层的小尺度变化
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
M. Tjernström
中科院分区：
文献类型：
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作者：
B. Grisogono;L. Ström;M. Tjernström
热驱动的中尺度环流在波罗的海西南海岸，瑞典东南部的主要大尺度风向的影响，检查。这项研究的目的是突出沿海大气边界层的小规模变化。在这项研究中使用的数值三维中尺度模式，这是集中在沿海射流，排水流，海风，特别是低层涡型流的整体行为。结果表明，天气条件，加上瑞典东南部的温和地形（最大。h 0 ≤ 206 m），控制着由海陆温差Δ T触发的海岸中尺度动力学。揭示了沿海低空急流和海风的微妙性质;它们的模式取决于天气气流、海岸线方向和Δ T之间的相互作用。模拟表明，沿海急流通常发生在夜间，高度、强度和相对于海岸的位置各不相同;它们与下坡气流和背景风相互作用。对于指定的地表温度（随海水温度变化±8 K）和相对的恒定地转风8 m·s-1时，排流对相对的环境流的影响比海风更强。根据所考虑的海岸部分和盛行的环境风，海风可以被抑制或增强，静止在海岸或快速渗透到内陆，与另一个动态系统同步，或者几乎独立地自我进化。分析了低层涡结构。它是由“倾斜”，“发散”和水平平流项。海岸效应的水平范围大致与Rossby变形半径一致。
The influence of the main large-scale wind directions on thermally driven mesoscale circulations at the Baltic southwest coast, southeast of Sweden, is examined. The aim of the study is to highlight small-scale alterations in the coastal atmospheric boundary layer. A numerical three-dimensional mesoscale model is used in this study, which is focused on an overall behaviour of the coastal jets, drainage flows, sea breezes, and a low-level eddy-type flow in particular. It is shown that synoptic conditions, together with the moderate terrain of the southeast of Sweden (max. height h0 ≤ 206 m), governs the coastal mesoscale dynamics triggered by the land-sea temperature difference Δ T. The subtle nature of coastal low-level jets and sea breezes is revealed; their patterns are dictated by the interplay between synoptic airflow, coastline orientation, and Δ T.The simulations show that coastal jets typically occur during nighttime and vary in height, intensity and position with respect to the coast; they interact with downslope flows and the background wind. For the assigned land surface temperature (varying ±8 K from the sea temperature) and the opposing constant geostrophic wind 8 m s-1, the drainage flow is more robust to the opposing ambient flow than the sea breeze later on. Depending on the part of the coast under consideration, and the prevailing ambient wind, the sea breeze can be suppressed or enhanced, stationary at the coast or rapidly penetrating inland, locked up in phase with another dynamic system or almost independently self-evolving. A low-level eddy structure is analyzed. It is governed by ‘tilting’, ‘divergence’ and horizontal advection terms. The horizontal extent of the coastal effects agrees roughly with the Rossby radius of deformation.