Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns

Abstract The existing theories for the tropical teleconnections to Indian summer monsoon (ISM) are diverse in approaches. As a result, it is impossible to quantify the relative impacts of different tropical climate patterns on ISM, complying with a single physical mechanism. Here, we show that tropi...

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Autores principales:	Arindam Chakraborty, Priyanshi Singhai
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/dfc3f6c9aca1453bbad35795c05f0afe
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spelling	oai:doaj.org-article:dfc3f6c9aca1453bbad35795c05f0afe2021-11-21T12:16:42ZAsymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns10.1038/s41598-021-01758-62045-2322https://doaj.org/article/dfc3f6c9aca1453bbad35795c05f0afe2021-11-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-01758-6https://doaj.org/toc/2045-2322Abstract The existing theories for the tropical teleconnections to Indian summer monsoon (ISM) are diverse in approaches. As a result, it is impossible to quantify the relative impacts of different tropical climate patterns on ISM, complying with a single physical mechanism. Here, we show that tropical teleconnections to ISM can be explained through net moisture convergence driven by surface pressure (Ps) gradients surrounding the Indian region. The positive and negative phases of major tropical climate patterns modulate these pressure gradients asymmetrically in the zonal and/or meridional directions leading to asymmetric changes in moisture convergence and ISM rainfall (ISMR). Stronger El Nino droughts than La Nina floods are due to greater decreased eastward moisture flux over the Arabian Sea during El Nino than the corresponding increase during La Nina driven by proportionate meridional Ps gradients. While the equatorial Atlantic Ocean’s sea surface temperature in boreal summer and El Nino Southern Oscillation in the preceding winter changes ISMR significantly, moisture convergence anomalies driven by the Indian Ocean Dipole were insignificant. Moreover, while ISMR extremes during ENSO are due to asymmetric changes in zonal and meridional gradients in Ps, non-ENSO ISMR extremes arise due to the zonal gradient in zonally symmetric Ps anomalies.Arindam ChakrabortyPriyanshi SinghaiNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-13 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Arindam Chakraborty Priyanshi Singhai Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns
description	Abstract The existing theories for the tropical teleconnections to Indian summer monsoon (ISM) are diverse in approaches. As a result, it is impossible to quantify the relative impacts of different tropical climate patterns on ISM, complying with a single physical mechanism. Here, we show that tropical teleconnections to ISM can be explained through net moisture convergence driven by surface pressure (Ps) gradients surrounding the Indian region. The positive and negative phases of major tropical climate patterns modulate these pressure gradients asymmetrically in the zonal and/or meridional directions leading to asymmetric changes in moisture convergence and ISM rainfall (ISMR). Stronger El Nino droughts than La Nina floods are due to greater decreased eastward moisture flux over the Arabian Sea during El Nino than the corresponding increase during La Nina driven by proportionate meridional Ps gradients. While the equatorial Atlantic Ocean’s sea surface temperature in boreal summer and El Nino Southern Oscillation in the preceding winter changes ISMR significantly, moisture convergence anomalies driven by the Indian Ocean Dipole were insignificant. Moreover, while ISMR extremes during ENSO are due to asymmetric changes in zonal and meridional gradients in Ps, non-ENSO ISMR extremes arise due to the zonal gradient in zonally symmetric Ps anomalies.
format	article
author	Arindam Chakraborty Priyanshi Singhai
author_facet	Arindam Chakraborty Priyanshi Singhai
author_sort	Arindam Chakraborty
title	Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns
title_short	Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns
title_full	Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns
title_fullStr	Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns
title_full_unstemmed	Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns
title_sort	asymmetric response of the indian summer monsoon to positive and negative phases of major tropical climate patterns
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/dfc3f6c9aca1453bbad35795c05f0afe
work_keys_str_mv	AT arindamchakraborty asymmetricresponseoftheindiansummermonsoontopositiveandnegativephasesofmajortropicalclimatepatterns AT priyanshisinghai asymmetricresponseoftheindiansummermonsoontopositiveandnegativephasesofmajortropicalclimatepatterns
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Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns

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