Study of thermodynamic indices in forecasting pre-monsoon thunderstorms over Kolkata during STORM pilot phase 2006–2008

Abstract

The pre-monsoon convective atmosphere over Kolkata (22.52°N, 88.37°E) during STORM field phase 2006-2008 is investigated using 12 UTC radiosonde data and thermodynamic indices. In the present study, an attempt has been made to assess the skill of various indices and parameters and to propose suitable threshold values in forecasting the occurrence of thunderstorm activity at Kolkata. The thermodynamic indices and parameters used in the present study are lifted index (LI), K index (KI), severe weather threat index (SWEAT), total totals index (TTI), convective available potential energy (CAPE), deep convection index (DCI), humidity index (HI), Boyden index (BI), dew point temperature at 850 hpa (DEW), relative humidity at 700 hpa (RH), and bulk Richardson number (BRN). Validation of the suggested threshold values of indices was conducted on the days of thunderstorm activity. It was found that one index alone cannot predict the occurrence of thunderstorm over Kolkata region. The present study suggests that the indices with highest skill for thunderstorm prediction are KI, DCI, SWEAT, DEW, HI, RH, LI, TTI, while the prediction efficiency is poor for CAPE, BRN, and BI. Observed values of these indices also reveal that scattered, multi-cellular thunderstorms are possible over Kolkata during pre-monsoon months.

Synoptic-Thermodynamic Analysis of Pervasive Hailstorm Case Study: Tehran, March 30, 2015

“…Being equipped with appropriate knowledge regarding natural disasters caused by climatic elements can reduce the destruction rate to a certain degree. Accuracy and importance of instability indices in this study is in agreement with that of the [33] who applied the mentioned five indices for the monsoon region. These indices can be applied at high levels of confidence to predict the occurrence of hail in Iran.…”

“…LNB Z And LFC Z are the heights of the level of neutral buoyancy and the level of free convection, respectively [33].…”

Positioning of lightning rods using Monte Carlo technique

“…On the other hand, for lightning attachment studies, it is not important how exactly the leader propagates between its origin (about 5e7 km) and about 1e2 km above ground. In this problem, the lower level that will create opposite charges on earth surface is taken to be 1000 m above ground [26]. Therefore, the height of origin of stepped leader from ground is taken as 1000 m to start the simulation.…”

Assessment of Convective Activity Using Stability Indices as Inferred from Radiosonde and MODIS Data

“…Over the Indian region, several studies were carried out about the relation of thunderstorm indices with thermodynamic parameters on convective activity (Kumar,[19]; Asoilal [20]; Lal [21]; Tyagi et al [22]; Litta and Mohanty [23]). The convective activity prevailing over the atmosphere is the feeding mechanism for the development of weather systems such as thunderstorms and cyclones.…”