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Large-scale dynamics have greater role than thermodynamics in driving precipitation extremes over India

Lookup NU author(s): Helen Fowler

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. The changing characteristics of precipitation extremes under global warming have recently received tremendous attention, yet the mechanisms are still insufficiently understood. The present study attempts to understand these processes over India by separating the ‘dynamic’ and ‘thermodynamic’ components of precipitation extremes using a suite of observed and reanalysis datasets. The former is mainly due to changes in atmospheric motion, while the latter is driven mainly by the changes associated with atmospheric moisture content. Limited studies have attributed dynamic and thermodynamic contributions to precipitation extremes, and their primary focus has been on the horizontal atmospheric motion component of the water budget. Our study, on the other hand, implements the decomposition of vertical atmospheric motion, based on the framework proposed by Oueslati et al. (Sci Rep 9: 2859, 2019), which has often been overlooked, especially for India. With the focus on two major and recent extreme events in the Kerala and Uttarakhand regions of India, we show that the vertical atmospheric motion has a more significant contribution to the events than the horizontal atmospheric motion. Further, decomposition of the vertical atmospheric motion shows that the dynamic component overwhelms the thermodynamic component’s contribution to these extreme events, which is found to be negligible. Using a threshold method to define extreme rainfall, we further extended our work to all India, and the results were consistent with those of the two considered events. Finally, we evaluate the contributions from the recently made available CMIP6 climate models, and the results are interestingly in alignment with the observations. The outcomes of this study will play a critical role in the proper prediction of rainfall extremes, whose value to climate adaptation can hardly be overemphasised.


Publication metadata

Author(s): Sudharsan N, Karmakar S, Fowler HJ, Hari V

Publication type: Article

Publication status: Published

Journal: Climate Dynamics

Year: 2020

Volume: 55

Pages: 2603-2614

Print publication date: 01/11/2020

Online publication date: 03/08/2020

Acceptance date: 29/07/2020

Date deposited: 23/08/2021

ISSN (print): 0930-7575

ISSN (electronic): 1432-0894

Publisher: Springer Nature

URL: https://doi.org/10.1007/s00382-020-05410-3

DOI: 10.1007/s00382-020-05410-3


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