The use and performance of mesoscale models over the Indian region for two high-impact events

Abstract

High-impact mesoscale weather events, occurring in different parts of India in all seasons, lead to major weather-and climate-related disasters. Several research groups and operational weather forecasting centres in India have adopted mesoscale models for research and operational usage. This paper reviews the work done by different groups with respect to two specific events, (1) unprecedented locally heavy rainfall near Mumbai (Santa Cruz) on 26 and 27 July 2005 and (2) the Orissa super-cyclone of 29 and 30 October 1999 from its incipient stage on 24 and 25 October 1999. Considerable variability in the prediction of the intensity and location of mesoscale heavy rainfall, as well as in the intensity and path of the super-cyclone, are found. In order to reduce uncertainty in dynamical prediction, it is necessary that the model dynamics, physics, resolution, boundary conditions and availability of data on land-ocean surface processes are tuned separately to the specific event types, such as heavy monsoon rainfall, tropical cyclone genesis and movement and severe local thunderstorms, as the processes controlling such types of events may require suitable treatments for their proper simulations through appropriate dynamics, physics and resolution.

A Study on Simulation of Heavy Rainfall Events Over Indian Region with ARW-3DVAR Modeling System

“…2b, a dark area representing the heavy precipitation zone is concentrated over Mumbai. (DODLA and RATNA, 2009;SIKKA and RAO, 2008;CHANG et al, 2008;RAMA RAO et al, 2007;VAIDYA and KULKARNI, 2007). The meso-convective systems associated with the rainfall event are successfully captured, but the model did not simulate the heavy rain amounts over Mumbai.…”

“…However, the forecast skill of these models is very limited, particularly for important variables like rainfall (ROY BHOWMIK and PRASAD 2001;RAMA RAO et al 2007;SIKKA and RAO 2008;DAS et al 2008). Hence, there is a necessity for efforts to improve performance of the mesoscale models in short-range predictions on a real-time basis for the Indian monsoon region particularly for prediction of the MCSs, which lead to heavy rainfall events.…”

Dynamics of Heavy Rain Spells over India during 2005

“…Many observational and simulation studies are available in the literature [5][6][7][8][9][10][11] for understanding the record heavy rainfall events over Mumbai on 26 th & 27 th July 2005. Francis et al [12] examined the incidence of such events along the west coast of India and found that the belt between 14˚N and 20˚N is especially susceptible to such events, which occur as a result of several factors such as the largescale strengthening of the monsoon winds over the Arabian Sea, the movement of monsoon depressions from the Bay of Bengal to central India along approximately 20-22˚N, the formation of mid-tropospheric cyclones (MTCs) and the presence of active off shore troughs in the lower troposphere along central and northern parts of the coast with the possibility of an embedded mesoscale cyclonic circulation.…”

High-Impact Weather Events over the SAARC Region

“…However, the forecast skill of these models is very limited, particularly for important variables like rainfall (Roy Bhowmik and Prasad 2001 ;Rama Rao et al 2007 ;Sikka and Rao 2008 ;Das et al 2008 ).…”