Work

Role of Autoconversion Parameterization in Coupled Climate Model for Simulating Monsoon Subseasonal Oscillations

Year: 2025

Type: article

Abstract: The Indian summer monsoon (ISM) and associated monsoon intraseasonal oscillations (MISOs) influence the billions of people living in the Indian subcontinent. This study explores the role of autoconversion parameterization in microphysical schemes for the simulation of MISO with the coupled climate model, for example, the Climate Forecast System version 2 (CFSv2), by conducting sensitivity experiments in two resolutions (∼100 and ∼38 km). Results reveal that the modified autoconversion parameterization better simulates the active‐break spells of the ISM rainfall. The main improvements include the contrasting features of rainfall over land and ocean and the MISO index, representing MISO periodicity. The improvements are qualitatively and quantitatively more significant in the higher‐resolution simulations, particularly regarding rainfall spatial patterns over the Indian subcontinent during active spells. The MISO monitoring index in the revised CFSv2 also shows improvement compared with the control run. This study concludes that proper autoconversion parameterization in the coupled climate model can lead to enhanced representation of active‐break spells and sub‐seasonal variability of ISM.

Source: Journal of Geophysical Research Atmospheres

DOI: 10.1029/2024jd042783

Authors: Ushnanshu Dutta, Moumita Bhowmik, Anupam Hazra, Suryachandra A. Rao, Jen‐Ping Chen

Institutions: National Taiwan University, Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Research Center for Environmental Changes, Academia Sinica

Language: English

Topic: Climate variability and models

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

SDG: Climate action

Open Access status: green

Funders: National Science and Technology Council, National Taiwan University