For the first time, surface layer variations of Convective regions (CRs) of Mesoscale Convective Systems (MCS) embedded in a cyclone, ‘Laila’ are examined over the Indian region during 17 – 21, May 2010 using PRWONAM measurements. CRs are detected in MCSs based on the Detect-And-Spread (DAS) algorithm applied on IR (InfraRed) Brightness Temperatures (IRBRT) for Bangalore station. During Jul-Aug in 2009 (2010), the CRs were detected only during 1400 IST – 0500 IST (Indian Standard Time = UTC+530 h) everyday with percentage of occurrence at 9.3 % (18.6 %). The detected CR in MCS within Laila during 1900 IST, 18 May – 0400 IST, 19 May is associated with stratiform region extending from 0000 IST to 0400 IST, 19 May. The striking observation is, a combination of (i) weak meso-low (L1) forming ahead of precipitating CR during 2104 IST – 2129 IST, 18 May, (ii) well-defined meso-high (H1) during precipitating CR, (iii) well-defined wake-low (L2) in the wake of the CR. A rise in surface specific humidity to 18.7 g kg −1 and convective activity intensifying with IRBRT at 190 K are observed ahead of precipitating CR. A meso-high (H1) formed in precipitating CR with wind gusting and surface cooling. A meso-low (L2) formed later with an amplitude at 2.2 hPa of the pressure couplet (H1, L2). The wake-low drying observed in surface specific humidity reduction by 3.9 g Kg −1 due to unsaturated air descent at back edge of trailing stratiform region into precipitating CR is indicated in wind direction change. Normalcy restored from wake-low conditions in 23 min. Further, the Surface layer variations in CRs of Normal (non-cyclone) MCSs of Pre, Onset, Peak monsoon phases of the southwest monsoon show similarities with MCS in Cyclone in meso-low (L1), meso-high (H1) and a wake low (L2) occurrences over Bangalore location.
Reddy et al. (Wed,) studied this question.