Assessment of Conditional Symmetric Instability from Global Reanalysis Data
Assessment of Conditional Symmetric Instability from Global Reanalysis Data
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根据全局再分析数据评估条件对称不稳定性
DOI：
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发表时间：
2018
影响因子：
3.1
通讯作者：
D. Kirshbaum
中科院分区：
文献类型：
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作者：
Ting‐Chen Chen;M. Yau;D. Kirshbaum
倾斜对流是释放潮湿对称不稳定性的过程，通常与带状云和降水有关，特别是在温带气旋的锋区。研究还表明，与倾斜对流相关的潜热释放可能导致表面锋生的旋转，从而增强温带气旋的快速增强。然而，大多数这些研究仅考虑局部区域或短时间持续时间。在这项研究中，我们从条件对称不稳定性及其与降水系统的关系方面，对倾斜对流潜在发生的全球气候学进行了新颖的统计调查。利用每6小时的ERA-Interim计算两个不同的指数，即倾斜对流可用势能（SCAPE）和可实现对称不稳定性垂直积分范围（VRS），以评估全球范围内发生倾斜对流的可能性。这些指数与观测到的表面降水以及气旋活动之间的关联程度被量化。还研究了中纬度气旋在其生命周期的不同阶段对倾斜对流的敏感性。与非爆炸性气旋情况相比，快速加深的气旋中的 SCAPE 和 VRS 的时间演化在快速增强开始之前表现出较高的值，并且在快速增强开始之后表现出更显着的下降，这支持了对称不稳定性的释放可能有助于风暴增强的观点。
Slantwise convection, the process by which moist symmetric instability is released, has often been linked to banded clouds and precipitation, especially in frontal zones within extratropical cyclones. Studies also suggest that the latent heat release associated with slantwise convection can lead to a spinup of surface frontogenesis, which can enhance the rapid intensification of extratropical cyclones. However, most of these studies considered only local areas or short time durations. In this study, we provide a novel statistical investigation of the global climatology of the potential occurrence of slantwise convection, in terms of conditional symmetric instability, and its relationship with precipitating systems. Using the 6-hourly ERA-Interim, two different indices are calculated, namely, slantwise convective available potential energy (SCAPE) and vertically integrated extent of realizable symmetric instability (VRS), to assess the likelihood of occurrence of slantwise convection around the globe. The degree of association is quantified between these indices and the observed surface precipitation as well as the cyclone activity. The susceptibility of midlatitude cyclones to slantwise convection at different stages of their life cycle is also investigated. As compared to the nonexplosive cyclone cases, the time evolution of SCAPE and VRS within rapidly deepening cyclones exhibit higher values before, and a more significant drop after, the onset of rapid intensification, supporting the idea that the release of symmetric instability might contribute to the intensification of storms.