Probing for overshooting as extreme event of thunderstorms
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Probing for overshooting as extreme event of thunderstorms S. Chaudhuri1 · F. Khan1 · D. Das1 · P. Mondal1 · S. Dey1 Received: 25 June 2018 / Accepted: 24 April 2020 © Springer Nature B.V. 2020
Abstract Thunderstorm overshooting is rare but not an unusual phenomenon in a metropolitan of India, Kolkata (22.57° N; 88.36° E) during the pre-monsoon months (April–May). An attempt is made in this study to identify the important parameters differentiating the thunderstorms in overshooting and non-overshooting categories through data analytics from 2000 to 2015. The present investigation on parametric classification would facilitate in estimating the predictability of thunderstorms with overshooting which subsequently might assist in operational forecast of thunderstorm severity over Kolkata. The altitudes of lifting condensation level (LCL), wind shear, bulk Richardson number (BRN), gust speed, boundary layer characteristics and their correlation with thunderstorm cloud top height (CTH) and also their variation and distribution during overshooting (OTS) and non-overshooting (TS) thunderstorms are analyzed in this study. The result depicts that over Kolkata the intensity of storms during OTS is higher than during TS though the frequency of OTS is less than that of TS. The results further show that the potential temperature (θ), equivalent potential temperature (θe), mixing ratio (es) in the boundary layer, convective available potential energy, convective inhibition energy, BRN and gust speed play significant roles in regulating the CTH during OTS and TS thunderstorms over Kolkata. Keywords Thunderstorm · Overshooting · Predictability · Severity · Stability indices
* S. Chaudhuri [email protected] F. Khan [email protected] D. Das [email protected] P. Mondal [email protected] S. Dey [email protected] 1
Department of Atmospheric Sciences, University of Calcutta, 51/2 Hazra Road, Kolkata 700 019, India
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Natural Hazards
1 Introduction The troposphere is the lower most part of the atmosphere where weather forms. However, occasionally the upper tropospheric outflow penetrates the tropopause when favorable conditions are met to develop deep convection. Thunderstorm is one of the intense convective systems in the troposphere which is responsible for disaster with loss of life and property. Therefore, thunderstorm characterization and accurate prediction becomes one of the major concerns of the society to minimize or avoid the associated destructions/damages. The dimension and variability of a thunderstorm cloud with respect to whether it penetrates the tropopause or not depends on several factors. The parametric classification of overshooting (OTS) and non-overshooting (TS) thunderstorms is therefore necessary for estimating the predictability and related intensity as, during OTS, generally thunderstorms are more severe. The association between overshooting cloud top and the occurrence of severe weather has been found in various literatures (Bedka 2011; Mikus an
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