A global spatiotemporal analysis of inland tropical cyclone maintenance or intensification
A global spatiotemporal analysis of inland tropical cyclone maintenance or intensification
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内陆热带气旋维持或加强的全球时空分析
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
J. M. Shepherd
中科院分区：
文献类型：
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作者：
T. K. Andersen;J. M. Shepherd
由于各种地面和大气特征的相互作用，预测热带气旋在陆地上的强度变化非常复杂。由于普遍不利的条件，许多台风在登陆后不久就减弱和衰减。在某些情况下，tc也可能转变为温带气旋（ETs）。尽管没有海洋强迫，但观测到一些热带气旋在内陆保持或增强强度，称为“热带气旋维持或增强”（TCMIs）。本研究确定了TCMIs的环境和特征，并探索了可能有助于产生有利于热带系统的大气的物理过程。目标是编制一个30年的内陆TC数据集，量化可能与陆地上最大强度相关的TC特征，并分析导致强度增强的地表和大气条件。在全球227个内陆tc中，45个在内陆保持或增强了强度：17个冷芯（ET）， 16个暖芯（TCMI）和12个混合病例。天气条件分析表明，当低层温度梯度较弱时，tc持续存在。在气旋增强时，土壤湿度梯度在气旋附近，可能通过增加的地表潜热通量（LHF）来强迫TCMIs。发现TCMI发生的区域平均LHF阈值约为70 W m−2。在每次TCMI之前的2周内，LHF在增强区域趋于高于平均水平，这进一步证明了地表强迫的存在。
Forecasting tropical cyclone (TC) intensity changes over land is complicated by interactions of various surface and atmospheric features. Due to generally unfavorable conditions, many TCs weaken and decay soon after landfall. In some cases, TCs may also transition to extratropical cyclones (ETs). Despite the absence of oceanic forcing, a number of TCs have been observed to maintain or increase strength inland, termed “tropical cyclone maintenance or intensification’ (TCMIs). This study identifies the environments and characteristic features of TCMIs and explores physical processes that may help to produce an atmosphere conducive for tropical systems. The objectives are to compile an inland TC dataset over a 30‐year period, quantify TC traits that may relate to maximum strength over land, and analyse surface and atmospheric conditions leading up to intensification. Of 227 inland TCs globally, 45 maintained or increased strength inland: 17 cold‐core (ET), 16 warm‐core (TCMI), and 12 hybrid cases. Analysis of synoptic conditions indicates that TCs persist when low‐level temperature gradients are weak. Soil moisture gradients were in the vicinity of the cyclones at the time of intensification and may be forcing the TCMIs via increased surface latent heat flux (LHF). The area‐averaged LHF threshold is found to be around 70 W m−2 for TCMI occurrence. In the 2 weeks leading up to each TCMI, the LHF tends to be higher than average over the intensification regions and provides further evidence of land surface forcing.