Role of cloud microphysics and energetics in regulating different phases of the monsoon low‐pressure systems over the Indian region

Monsoon low‐pressure systems (LPS) are the major contributor to these heavy rainfall events and pose a significant challenge to operational forecasting agencies in terms of prediction accuracy with adequate lead time, particularly at a district scale. The present study investigates the role of micro...

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Bibliographic Details
Published in:Quarterly journal of the Royal Meteorological Society 2023-01, Vol.149 (751), p.349-368
Main Authors: Hazra, Vivekananda, Pattnaik, Sandeep
Format: Article
Language:English
Subjects:
Cloud microphysics
cloud microphysics parameterization
Emergency preparedness
Heavy rainfall
Indian summer monsoon
Kinetic energy
Kinetic energy generation
Lipopolysaccharides
Lower troposphere
low‐pressure systems
Microphysics
Mitigation
Monsoons
Precipitation
Rainfall
Storms
Troposphere
Updraft
Vulnerability
Weather forecasting
WRF
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Summary:Monsoon low‐pressure systems (LPS) are the major contributor to these heavy rainfall events and pose a significant challenge to operational forecasting agencies in terms of prediction accuracy with adequate lead time, particularly at a district scale. The present study investigates the role of microphysical parameterizations associated with these LPS during the intensification phases, that is, depressions (MD) and deep depressions (DD), using the Weather Research and Forecasting (WRF) model. A total of 130 simulations are carried out (12 MD and 14 DD) using five cloud microphysical parameterizations, that is, WSM6, WDM6, Thompson, Milbrandt, and Aerosol Aware Thompson, up to 96 hr. The study aims to interlink rainfall vulnerability and LPS intensity both at the district scale for the state of Odisha (India). Results suggest that Mayurbhanj is the most vulnerable district in terms of rainfall. The WDM6 has the best skills in terms of rainfall. The analysis of storm energetics is carried out to provide a possible clue about the mechanism facilitating the intensification of specific LPS to DD. Results suggest that DDs are more thermodynamically efficient than MDs to convert the latent energy to kinetic energy, facilitating its intensification process through higher kinetic energy generation and moisture consumption. Further, it is found that deep vertical updraft with the strong inward flow in the lower troposphere supported by intense tangential wind within the 300 km radial periphery is distinct in DD compared to MD. The findings of the study will have direct implications on localized forecast, policy planning, disaster preparedness, mitigation, and adaptation. The study found a possible clue about how some low‐pressure systems (LPS) during the southwest monsoon (over the Indian region) become deep depressions (DD) from the point of view of the energy budget. Results suggest that DDs are more thermodynamically efficient than depressions (MD) at converting the latent energy to kinetic energy, which speeds up the intensification process by increasing kinetic energy generation and moisture consumption. The deep vertical updraft with a substantial inward flow in the lower troposphere supported by strong tangential wind within the 300 km radial periphery is evident in the DD phase of the storm. Results from 26 cases (12 MD, 14 DD), also suggest that the WDM6 cloud microphysics scheme has the best rainfall forecasting skills at the district scale with a lead up t
ISSN:0035-9009
1477-870X
DOI:10.1002/qj.4396