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Pre-monsoon/monsoon thunderstorm characteristics over Pune-An investigation using Doppler Sodar observations

Murthy, BS and Latha, R and Sreeja, P and Kalapureddy, MCR and Dharmaraj, T and Waghmare, RT (2011) Pre-monsoon/monsoon thunderstorm characteristics over Pune-An investigation using Doppler Sodar observations. Journal of Atmospheric and Solar-Terrestrial Physics, 73 (16). pp. 2356-2366.

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Abstract

Doppler sodar observations of three dimensional (3D) wind fields and thermal structure of convective boundary layer (CBL) on a few thunderstorm days of 2009 during pre-monsoon (May and June; June due to delayed arrival of monsoon over Pune) and monsoon (July and August) are analyzed. They reveal the typical signatures of wind fields for the late afternoon thunderstorm (TS) such as deceleration of winds with or without change in direction leading to convergence a few minutes (∼15–30 min) prior to the onset of TS. Pre-monsoon TS are characterized by broad updrafts and narrow downdrafts in CBL in contrast to the narrow updrafts and broad downdrafts of a normal day (i.e. No-TS day). Mean vertical velocity averaged over CBL period shows net updraft on TS days and net downdraft on No-TS day for the pre-monsoon cases. Similarly calm winds are observed in the CBL on TS-days that support enhanced free convection. During the monsoon period updrafts are observed on both TS and No-TS days with higher values on TS days in comparison, due to the dominance of large-scale monsoon flow over local convection. Relatively higher turbulence kinetic energy (TKE) in CBL is observed on all TS days. Analysis shows that TKE maximum for the day is attained about 1.5–2.0 h prior to the onset of afternoon TS. Mixed-layer depth, determined from TKE profile, is higher than lifting condensation level (LCL) on TS days in May and June indicating saturation of air parcels in updrafts.

Item Type: Article
Additional Information: Copyright of this article belongs to Elsevier.
Uncontrolled Keywords: Convective boundary layers; Local thunderstorm; Synoptic forcing; Turbulent kinetic energy; Vertical velocity, Boundary layers; Electron energy loss spectroscopy; Kinetic energy; Three dimensional; Thunderstorms; Wind power, Atmospheric thermodynamics
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 11 Aug 2014 09:10
Last Modified: 11 Aug 2014 09:10
URI: http://moeseprints.incois.gov.in/id/eprint/694

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