Assimilation of doppler weather radar data through rapid intermittent cyclic (RIC) for simulation of squall line event over India and adjoining Bangladesh

Abstract

A squall line is a cluster of severe thunderstorms or storm cells that have formed into a line. Squall lines are hundreds of kilometres in length and having a life span of several hours, which is considerably longer than embedded thunderstorms. Squall lines generate gusty winds, sudden changes in the wind direction with an abrupt increase in wind speed and heavy rains with thunder which are more intense and extensive than individual thunderstorms. The severe gust associated with squall lines can exceed 100 km per hour. Some of them even carry hails and tornadoes. Area under influence of squall lines is extremely unstable and severely turbulent. Over Indian subcontinent, squall lines are often observed during the late pre-monsoon and early summer southwest monsoon over north-eastern states of India and adjoining Bangladesh. Squall line in Doppler Weather Radar (DWR) image will have solid line of heavy rainfall followed by a large area of light rainfall.