Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation

Abstract This work explores the effect of convective self‐aggregation on extreme rainfall intensities through an analysis at several stages of the cloud lifecycle. In addition to increases in 3‐hourly extremes consistent with previous studies, we find that instantaneous rainrates increase significan...

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Autores principales:	Nicolas A. Da Silva, Caroline Muller, Sara Shamekh, Benjamin Fildier
Formato:	article
Lenguaje:	EN
Publicado:	American Geophysical Union (AGU) 2021
Materias:	self‐aggregation convection precipitation extremes microphysics Physical geography GB3-5030 Oceanography GC1-1581
Acceso en línea:	https://doaj.org/article/a70c244fe5094270b547e009ec69bc32
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spelling	oai:doaj.org-article:a70c244fe5094270b547e009ec69bc322021-11-30T08:40:32ZSignificant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation1942-246610.1029/2021MS002607https://doaj.org/article/a70c244fe5094270b547e009ec69bc322021-11-01T00:00:00Zhttps://doi.org/10.1029/2021MS002607https://doaj.org/toc/1942-2466Abstract This work explores the effect of convective self‐aggregation on extreme rainfall intensities through an analysis at several stages of the cloud lifecycle. In addition to increases in 3‐hourly extremes consistent with previous studies, we find that instantaneous rainrates increase significantly (+30%). We mainly focus on instantaneous extremes and, using a recent framework, relate their increase to increased precipitation efficiency: the local increase in relative humidity drives larger accretion efficiency and lower re‐evaporation. An in‐depth analysis based on an adapted scaling for precipitation extremes reveals that the dynamic contribution decreases (−25%) while the thermodynamic is slightly enhanced (+5%) with convective self‐aggregation, leading to lower condensation rates. When the atmosphere is more organized into a moist convecting region and a dry convection‐free region, deep convective updrafts are surrounded by a warmer environment which reduces convective instability and thus the dynamic contribution. The moister boundary‐layer explains the positive thermodynamic contribution. The microphysic contribution is increased by +50% with aggregation. The latter is partly due to reduced evaporation of rain falling through a moister near‐cloud environment, but also to the associated larger accretion efficiency. Thus, a potential change in convective organization regimes in a warming climate could lead to an evolution of tropical precipitation extremes significantly different than that expected from thermodynamical considerations. The relevance of self‐aggregation to the real tropics is still debated. Improved fundamental understanding of self‐aggregation, its sensitivity to warming and connection to precipitation extremes, is hence crucial to achieve accurate rainfall projections in a warming climate.Nicolas A. Da SilvaCaroline MullerSara ShamekhBenjamin FildierAmerican Geophysical Union (AGU)articleself‐aggregationconvectionprecipitation extremesmicrophysicsPhysical geographyGB3-5030OceanographyGC1-1581ENJournal of Advances in Modeling Earth Systems, Vol 13, Iss 11, Pp n/a-n/a (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	self‐aggregation convection precipitation extremes microphysics Physical geography GB3-5030 Oceanography GC1-1581
spellingShingle	self‐aggregation convection precipitation extremes microphysics Physical geography GB3-5030 Oceanography GC1-1581 Nicolas A. Da Silva Caroline Muller Sara Shamekh Benjamin Fildier Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation
description	Abstract This work explores the effect of convective self‐aggregation on extreme rainfall intensities through an analysis at several stages of the cloud lifecycle. In addition to increases in 3‐hourly extremes consistent with previous studies, we find that instantaneous rainrates increase significantly (+30%). We mainly focus on instantaneous extremes and, using a recent framework, relate their increase to increased precipitation efficiency: the local increase in relative humidity drives larger accretion efficiency and lower re‐evaporation. An in‐depth analysis based on an adapted scaling for precipitation extremes reveals that the dynamic contribution decreases (−25%) while the thermodynamic is slightly enhanced (+5%) with convective self‐aggregation, leading to lower condensation rates. When the atmosphere is more organized into a moist convecting region and a dry convection‐free region, deep convective updrafts are surrounded by a warmer environment which reduces convective instability and thus the dynamic contribution. The moister boundary‐layer explains the positive thermodynamic contribution. The microphysic contribution is increased by +50% with aggregation. The latter is partly due to reduced evaporation of rain falling through a moister near‐cloud environment, but also to the associated larger accretion efficiency. Thus, a potential change in convective organization regimes in a warming climate could lead to an evolution of tropical precipitation extremes significantly different than that expected from thermodynamical considerations. The relevance of self‐aggregation to the real tropics is still debated. Improved fundamental understanding of self‐aggregation, its sensitivity to warming and connection to precipitation extremes, is hence crucial to achieve accurate rainfall projections in a warming climate.
format	article
author	Nicolas A. Da Silva Caroline Muller Sara Shamekh Benjamin Fildier
author_facet	Nicolas A. Da Silva Caroline Muller Sara Shamekh Benjamin Fildier
author_sort	Nicolas A. Da Silva
title	Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation
title_short	Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation
title_full	Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation
title_fullStr	Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation
title_full_unstemmed	Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation
title_sort	significant amplification of instantaneous extreme precipitation with convective self‐aggregation
publisher	American Geophysical Union (AGU)
publishDate	2021
url	https://doaj.org/article/a70c244fe5094270b547e009ec69bc32
work_keys_str_mv	AT nicolasadasilva significantamplificationofinstantaneousextremeprecipitationwithconvectiveselfaggregation AT carolinemuller significantamplificationofinstantaneousextremeprecipitationwithconvectiveselfaggregation AT sarashamekh significantamplificationofinstantaneousextremeprecipitationwithconvectiveselfaggregation AT benjaminfildier significantamplificationofinstantaneousextremeprecipitationwithconvectiveselfaggregation
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Significant Amplification of Instantaneous Extreme Precipitation With Convective Self‐Aggregation

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