Impact of Horizontal Grid Resolutions for Thunderstorms Simulation over Bangladesh Using WRF-ARW Model

Md. Joshem Uddin, M. A. Samad, M. A. K. Mallik

Abstract


In this paper, an attempt has been made to study the physical and dynamical characteristics of three thunderstorms that occurred on 06 May 2017 over Mymensingh, Chuadanga, and Sylhet in Bangladesh by the WRF-ARW model of 5 and 10 km horizontal resolutions, and to find out the impacts of horizontal grid resolution for simulating thunderstorm events. The model was run for 48 h using global Final Analysis (FNL) data. Various meteorological parameters such as Mean Sea Level Pressure (MSLP), wind pattern at several pressure levels, relative humidity, and radar reflectivity along with the atmospheric instability index are analyzed and compared with the observed data of Bangladesh Meteorological Department (BMD). The model has captured the low pressure area, the conjugation of easterly and westerly wind, the presence of strong convection, high magnitude of vertical wind shear, marked dry-line, updraft, and downdraft reasonably well for the finest grid resolution. But the convective available potential energy (CAPE) value is found almost similar near the places of occurrence for both resolutions. The model performance is found precisely well for the finest than that of coarse horizontal grid resolution.

Keywords


Thunderstorms, WRF, CAPE, Grid resolutions, Dry-line, MSLP, Relative humidity

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Dhaka University Journal of Science ISSN 1022-2502 (Print) 2408-8528 (Online)