Simulation of Indian Summer Monsoon Rainfall (ISMR) with fully coupled regional chemistry transport model: A case study for 2017

Sreyashi Debnath, Chinmay Jena, Sachin D. Ghude, Rajesh Kumar, Gaurav Govardhan, Preeti Gunwani, Subodh Kumar Saha, Anupam Hazra, Samir Pokhrel

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The Indian subcontinent is a major hotspot of enhanced aerosol loading and emission of various chemical compounds due to extensive anthropogenic activities that profoundly impact the hydrological cycle of this region. Using coupled regional atmospheric chemistry transport model, WRF-Chem (Weather Research and Forecasting model coupled with chemistry) with fully interactive chemistry and dynamics, we carried out two sets of 122-days simulation experiments: (1) a control experiment without embedding chemistry and (2) a sensitivity experiment with embedding fully coupled MOZART-MOSAIC chemistry, to examine the impact of chemistry on the Indian Summer Monsoon Rainfall (ISMR) of 2017. The results show that inclusion of chemistry in the model plays a role in altering the spatial distribution of ISMR, reflected by a reduced mean rainfall by about 3 mm/day over the Indian subcontinent. The mean bias of model simulated rainfall reduces from 2.73 mm/day (excluding chemistry) to 1.6 mm/day (including chemistry), and from 1.2 mm/day (excluding chemistry) to 0.81 mm/day (including chemistry) when compared with IMD (India Meteorological Department) and TRMM (Tropical Rainfall Measuring Mission) rainfall data, respectively. Additionally, we found that inclusion of interactive chemistry causes a decrease in the daily convective rainfall by about 3 mm that is contributing largely to the mean rainfall differences. Further, analysis of hydrometeors indicates that the chemistry interacts with the cloud microphysics by modulating the hydrometeor paths of different cloud hydrometeors that consequently impacts the simulation of ISMR over this region. Results indicate that the virtue of detailed and more realistic representation of chemistry in the model has led to more realistic simulation and cannot be ignored in numerical forecasting of ISMR.
Original languageEnglish (US)
Pages (from-to)118785
JournalAtmospheric Environment
StatePublished - Oct 2021
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2021-11-05
Acknowledgements: Authors would like to acknowledge the Director, IITM for the support and providing necessary facilities to carry out the research work. We would thank the high-performance computing support team of Aditya and Pratyush HPC systems of the Indian Institute of Tropical Meteorology, Pune. We acknowledge the use of the WRF-Chem pre-processor tools provided by the Atmospheric Chemistry Observations and Modeling Laboratory (ACOM) of NCAR. We would like to thank Goddard Earth Sciences Data and Information Services Center (GES DISC) for providing TRMM precipitation dataset, India Meteorological Department (IMD) for providing gridded rainfall data and National Aeronautics and Space Administration (NASA), Goddard Space Flight Center for providing MODIS Atmosphere L2 Aerosol Product. The first author (SD) would like to acknowledge Dr. Rama Krishna Karumuri, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia, for his guidance during the preliminary model experimental runs. This work is a part of the Ph.D. thesis of the first author (SD). The authors sincerely thank the anonymous reviewer and the editor of the journal for their insightful comments and valuable suggestions.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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