Role of Convective Outflows Over the Rain Shadow Region of the Indian Peninsula: A Benchmark Case Study of Long-Lasting Precipitation Event

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

pure and applied geophysics Pub Date : 2024-12-27 DOI:10.1007/s00024-024-03634-6

J Sandeep, Thara Prabhakaran, Y. Jayarao, P. Murugavel

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引用次数: 0

Abstract

An investigation of a linear cloud cluster (CC) that brought 7 hours of rainfall over the arid rain shadow region of peninsular India, is the topic of this study. We present detailed insights from microphysical and dynamical interactions using radar observations and cloud-resolving simulations. The cloud-resolving model at 1 km resolution simulated the cold pools and strong gust fronts close to the observation. Gust fronts and their interactions paved way for increased convection organization and aggregation. The heavy rainfall was triggered by the impact of the cold pools in the late evening hours, even though suitable conditions with low convective inhibition and high convective available potential energy were present. The enhancement of equivalent potential temperature (θ_E) within the 15 km deep layer on the intersection of gust front triggered deep moist convection. The model could simulate the precipitating core and midlevel moistening in the storm's leading edge, thereby facilitating the propagation of convection. The unique aspect is the extended area of rainfall with the two confluent gust fronts and merging of the cold pools. However, high θ_E regions were found to trigger new convection. The optimal state of the Rotunno–Klemp–Weisman (RKW) theory was noted with moderate wind shears throughout the storm lifecycle, except during the most intensified stage with significant condensate loading and strongest updrafts. The updraft mass fluxes were enhanced after the gust front intersection and have contributed to deeper convection and enhanced precipitation. The longevity of the precipitation over seven hours maybe attributed to sustained updrafts and moistening of the middle layers, triggering new convection under the influence of several cold pool outflows.

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印度半岛雨影区对流外流的作用：一个长期降水事件的基准案例研究

对在印度半岛干旱雨影区带来7小时降雨的线性云团（CC）的调查是本研究的主题。我们提出了使用雷达观测和云分辨模拟从微物理和动态相互作用的详细见解。1 km分辨率的云分辨模式模拟了靠近观测点的冷池和强阵风锋。阵风锋及其相互作用为对流组织和聚集的增加铺平了道路。尽管存在低对流抑制和高对流有效势能的适宜条件，但此次强降水还是在深夜由冷池的影响引发的。阵风锋交汇处15 km深层等效位温θE的增强触发了深层湿对流。该模式可以模拟风暴前缘的降水核和中层湿润，有利于对流的传播。独特的方面是两个阵风锋汇合和冷池合并的降雨面积扩大。然而，高θE区域被发现引发了新的对流。Rotunno-Klemp-Weisman （RKW）理论的最佳状态是在整个风暴生命周期中出现中等风切变，除了在最强烈的阶段有显著的凝析油负荷和最强的上升气流。阵风锋交汇后，上升气流质量通量增强，对流加深，降水增强。持续7小时以上的降水可能是由于持续的上升气流和中层的润湿，在几次冷池流出的影响下引发了新的对流。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

pure and applied geophysics 地学-地球化学与地球物理

CiteScore

4.20

自引率

5.00%

发文量

240

审稿时长

9.8 months

期刊介绍： pure and applied geophysics (pageoph), a continuation of the journal "Geofisica pura e applicata", publishes original scientific contributions in the fields of solid Earth, atmospheric and oceanic sciences. Regular and special issues feature thought-provoking reports on active areas of current research and state-of-the-art surveys. Long running journal, founded in 1939 as Geofisica pura e applicata Publishes peer-reviewed original scientific contributions and state-of-the-art surveys in solid earth and atmospheric sciences Features thought-provoking reports on active areas of current research and is a major source for publications on tsunami research Coverage extends to research topics in oceanic sciences See Instructions for Authors on the right hand side.