How do the characteristics of monsoon low pressure systems over India change under a warming climate? A modeling study using the NCAR CESM

Thomas, TM and Bala, G and Vemavarapu, SV (2023) How do the characteristics of monsoon low pressure systems over India change under a warming climate? A modeling study using the NCAR CESM. In: Climate Dynamics .

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Abstract

In this study, using the NCAR Community Earth System Model (CESM1.2.2), we investigate the changes in the characteristics of the summer monsoon low pressure systems (LPS) over India in a twenty-first century climate change simulation corresponding to the RCP8.5 scenario. A slight weakening in monsoon circulation and an increase in mean summer monsoon precipitation over India are simulated in a warmer climate, consistent with several previous studies. The weakening of the monsoon circulation is associated with a pair of anticyclonic anomalies straddling the equator in the low level, weakening the cross-equatorial monsoonal flow from the southern hemisphere. These low-level circulation anomalies appear to be robust features in the equatorial Indian Ocean under climate change. An increase in moisture flux is also simulated over the Indian subcontinent. However, we find no significant change in the number of LPS or their spatial distribution under the RCP8.5 scenario. This is attributed to a small but non-significant decrease in the low-level meridional cyclonic shear in zonal winds. An increase in the intensity and frequency of extreme precipitation over India in a warmer world is simulated and is likely associated with an increase in moisture content. Our study shows that the fractional contribution of LPS to mean and extreme precipitation over India in a warmer world is likely unchanged, but the frequency and intensity of extreme events are larger. Because of the diversity in the results from single model studies on LPS characteristics in a warmer world, a future study that uses CMIP6 multi-model data would be valuable to assess the robustness and the uncertainty in changes in LPS activities under climate change.

Item Type:	Journal Article
Publication:	Climate Dynamics
Publisher:	Springer Science and Business Media Deutschland GmbH
Additional Information:	The copyright for this article belongs to the Springer Science and Business Media Deutschland GmbH.
Keywords:	Climate change; Extreme precipitation; Indian summer monsoon; Meridional cyclonic shear; Monsoon low pressure systems
Department/Centre:	Division of Interdisciplinary Sciences > Interdisciplinary Centre for Water Research Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences Division of Mechanical Sciences > Civil Engineering
Date Deposited:	13 Jul 2023 09:45
Last Modified:	08 Aug 2023 06:34
URI:	https://eprints.iisc.ac.in/id/eprint/82415

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