Numerical Study of Precipitation Core-Gap Structure along Cold Fronts
Numerical Study of Precipitation Core-Gap Structure along Cold Fronts
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DOI：
10.1175/jas3987.1
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发表时间：
2007-07
影响因子：
3.1
通讯作者：
Masayuki Kawashima
中科院分区：
文献类型：
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作者：
Masayuki Kawashima
摘要通过对冷锋理想化云分辨模拟的分析，探讨了沿着狭窄冷锋雨带（NCFRs）降水核心间隙结构的机制。在控制模拟中，锋前热层结的特征是低层弱对流不稳定，对流可用位能（CAPE）为1.60 J kg−1，再现了观测到的NCFRs的典型沿锋变化。模拟的NCFR被分解成规则间隔的，椭圆形的核心在一个顺时针方向的冷锋的角度。虽然水平剪切不稳定性（HSI）经常被认为是导致NCFRs沿锋面变化的一种机制，但在冷锋前缘模拟的垂直涡度场中没有识别出HSI的特征。降水的沿锋变化是由于冷锋前缘上方形成的波浪状扰动。波浪...
Abstract The mechanism responsible for the core-gap structure of precipitation along narrow cold-frontal rainbands (NCFRs) is investigated through analyses of idealized cloud-resolving simulations of cold fronts. The control simulation, in which the prefrontal thermal stratification is characterized by a weak convective instability at low levels with convective available potential energy (CAPE) of ∼60 J kg−1, reproduces the typical alongfront variability of observed NCFRs. The simulated NCFR is broken up into regularly spaced, ellipsoidal cores oriented at a clockwise angle to the cold front. While horizontal-shear instability (HSI) has frequently been proposed as a mechanism leading to the alongfront variability of NCFRs, no characteristic features of HSI are recognized in the simulated vertical vorticity field at the leading edge of the cold front. The alongfront variability in precipitation is attributed to the formation of a wavelike disturbance just above the leading edge of the cold front. The wave ...