A Comparison of precipitation distribution of two landfalling tropical cyclones during the extratropical transition
A Comparison of precipitation distribution of two landfalling tropical cyclones during the extratropical transition
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DOI：
10.1007/s00376-011-0148-y
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发表时间：
2011-10
影响因子：
5.8
通讯作者：
Guanghua Chen
中科院分区：
文献类型：
--
作者：
Guanghua Chen
本文研究了两个登陆热带气旋在温带过渡期间的降水分布。它们的区别是，大部分降水落在一个TC的TC路径的左侧，而在另一个TC的右侧。分析表明，在2004年的“海马”台风过程中，伴随着一个贯穿对流层的中纬度深槽的临近，台风北侧东南风气流的暖湿平流有利于台风西北侧的暖平流和锋生。由于等效位温（θe）的陡化，气团沿θ面沿着抬升，与锋生相关的热力直接环流共同作用，导致TC西北部降水增强。相反，对于TC Matsa（2005）来说，在潮湿的环境中，一个弱的中纬度槽位于中上层。低层条件不稳定触发对流，中高层动力强迫维持对流，使强降水发生在热带气旋东北部。对于这两个TC的情况下，降水增强也与高空异常散度与急流入口右侧的急流相关的强迫。从准地转的角度来看，由热成风的地转绝对涡度平流最有可能作为一个指示，反映垂直运动相对于TC中心的位移。
The precipitation distributions associated with two landfalling tropical cyclones (TCs) during extratropical transition (ET) were examined in this study. Their distinction is that the bulk of precipitation fell to the left of the TC track in one TC and to the right in the other. The analyses indicate that, for the TC Haima (2004) case, accompanied by the approach of a deep midlatitude trough throughout the depth of the troposphere, the warm and moist air advection by the southeasterly flow north of TC was favorable for warm advection and frontogenesis to the northwest of the TC. Due to the steepening of equivalent potential temperature (θe), the air-parcel uplift along theθesurface, in collaboration with thermally direct circulation related to frontogenesis, led to enhanced precipitation northwest of the TC. In contrast, for TC Matsa (2005) embedded within a moister environment, a weak midlatitude trough was situated at the mid-upper level. The convection was triggered by the conditional instability at the lower level and then sustained by dynamic forcing at the mid-upper level so that the heavy precipitation occurred to the northeast of TC. For the two TC cases, the precipitation enhancement was also linked to the upper-level anomalous divergence associated with the jet-related forcing on the right side of the jet entrance. From the quasigeostrophic perspective, the advection of geostrophic absolute vorticity by the thermal wind most likely served as an indication reflecting the displacement of the vertical motion relative to the center of the TC.