The combined influence of west pacific subtropical high and tropical cyclones over the northwest Pacific on Indian summer monsoon rainfall

IF 3 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Quarterly Journal of the Royal Meteorological Society Pub Date : 2023-12-11 DOI:10.1002/qj.4640

Roja Chaluvadi, Hamza Varikoden, Milind Mujumdar, S. T. Ingle

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Abstract

The present study examined the interrelationship between the Indian summer monsoon (ISM) rainfall, west Pacific subtropical high (WPSH) and Tropical cyclone (TC) activity over the western north Pacific (WNP) Ocean during the peak monsoon season in 1951-2019. When WNP TCs are inactive (active), there is a noticeable 10° westward (eastward) shift is observed along with intensification (weakening) of WPSH. The WPSH and WNP TC activities are divided into four categories: Eastward shift of WPSH with active TCs (EA) and inactive TC (EI), westward shift of WPSH with active TCs (WA) and inactive TCs (WI) in order to investigate the combined influence of WPSH and WNP TCs on ISMR during NonENSO, El Niño, and La Niña. In EA NonENSO cases, a surplus (deficit) rainfall was noticed over central (southern peninsular) India as a result of moisture convergence (low CAPE, abnormal moisture divergence and downdraft); however, the rainfall is above normal over the Indian subcontinent. During EI NonENSO case, an excess (deficit) regional rainfall activity was observed over eastcentral India and parts of north India (southern peninsular India) through regional changes in atmospheric circulations and mid-tropospheric vertical velocity. In contrast, WI (WA) NonENSO cases, the majority of India (southern peninsular and northeast India) experiences excessive precipitation while east-central India (east and west central India) undergoes deficit rainfall. This pattern is consistent with the spatial distribution of moisture flux convergence, CAPE and mid-tropospheric vertical velocity. In the case of NonENSO, the westward shift of WPSH associated with inactive TCs is one of the favourable conditions for ISMR. In general, the effect of eastward (westward) shift of WPSH along with more (less) TC during NonENSO case is favourable to ISMR. On the other hand, rainfall patterns during ENSO are significantly associated with the circulation changes teleconnected to the El Niño and La Niña conditions.

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西太平洋副热带高压和西北太平洋热带气旋对印度夏季季风降雨的共同影响

本研究探讨了 1951-2019 年季风旺季期间印度夏季季风（ISM）降雨量、西太平洋副热带高压（WPSH）和西北太平洋热带气旋（TC）活动之间的相互关系。当 WNP 热带气旋不活跃（活跃）时，WPSH 会明显西移（东移）10°，同时 WNP 热带气旋也会增强（减弱）。WPSH 和 WNP 热带气旋的活动分为四类：为了研究非ENSO、厄尔尼诺和拉尼娜期间 WPSH 和 WNP 热气旋对 ISMR 的综合影响，我们将 WPSH 和 WNP 热气旋活动分为四类：WPSH 东移与活跃热气旋（EA）和不活跃热气旋（EI）、WPSH 西移与活跃热气旋（WA）和不活跃热气旋（WI）。在 EA 非ENSO 情况下，由于水汽辐合（低 CAPE、异常水汽辐散和下沉气流），印度中部（半岛南部）降雨过多（不足）；但印度次大陆降雨量高于正常水平。在 EI NonENSO 情况下，通过区域大气环流和中对流层垂直速度的变化，在印度中东部和印度北部部分地区（印度半岛南部）观测到区域降雨活动过多（过少）。与此相反，在 WI（WA）非ENSO 情况下，印度大部分地区（印度半岛南部和东北部）降水过多，而印度中东部（印度东部和中西部）降水不足。这种模式与水汽通量辐合、CAPE 和中对流层垂直速度的空间分布一致。就 NonENSO 而言，与不活跃的热带气旋相关的 WPSH 西移是 ISMR 的有利条件之一。一般来说，在非ENSO情况下，WPSH东移（西移）和较多（较少）TC的影响有利于ISMR。另一方面，厄尔尼诺/南方涛动期间的降雨模式与厄尔尼诺和拉尼娜情况下的环流变化密切相关。

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

Quarterly Journal of the Royal Meteorological Society 地学-气象与大气科学

CiteScore

16.80

自引率

4.50%

发文量

163

审稿时长

3-8 weeks

期刊介绍： The Quarterly Journal of the Royal Meteorological Society is a journal published by the Royal Meteorological Society. It aims to communicate and document new research in the atmospheric sciences and related fields. The journal is considered one of the leading publications in meteorology worldwide. It accepts articles, comprehensive review articles, and comments on published papers. It is published eight times a year, with additional special issues. The Quarterly Journal has a wide readership of scientists in the atmospheric and related fields. It is indexed and abstracted in various databases, including Advanced Polymers Abstracts, Agricultural Engineering Abstracts, CAB Abstracts, CABDirect, COMPENDEX, CSA Civil Engineering Abstracts, Earthquake Engineering Abstracts, Engineered Materials Abstracts, Science Citation Index, SCOPUS, Web of Science, and more.