[1] Satellite (LIS) based lightning flash grid (0.5°Â 0.5°) data for the Indian land mass region covering from 8°-33°N and 73°-86°E for a period of 4 years (1998 -2001) were used to study the diurnal variation with one hour time resolution. The analysis revealed that there exists a strong diurnal cycle in the lightning activity with a prominent peak around 1000 UTC. An examination of seasonal diurnal variation suggests that the lightning activity was found highest in premonsoon and lowest in the postmonsoon season.
Monthly variations of lightning activity over typical land and oceanic regions of India were examined using satellite data (OTD) for a 5-year period (1995)(1996)(1997)(1998)(1999). It is noted that the nature of variation between surface air maximum temperature (T max ), thunderstorm days (Th n ), and lightning flash count over ER and WR showed remarkable correspondence and sensitivity with each other on monthly time scale. As we move out of winter season and enter the monsoon season, via pre-monsoon season, the WR undergoes cooling relative to the ER in the range 0.1-1.2 • C. As a result, WR experiences reduction of thunder days and lowering in flash count. This decrease in T max , Th n , and flash count over WR may also be associated with relatively small values of T θw and CAPE in comparison with similar values over ER during the monsoon season. Our observation of associated reduction in Th n and lightning count per 1 • C cooling in surface air maximum temperature suggests reduction of ∼ 3.5 thunderstorms per station and 73 flashes. Comparison of lightning flashes between pairs of coastal, oceanic, arid-zone, hilly, and island stations reveals distinct relationship between climate regime and intensity of lightning activity. We may conclude the results of this study by saying that the overhead lightning activity is a clear reflection of the status of the underlying ground-earth properties. A close and continuous monitoring of lightning activity may be considered as a need of present day scientific studies.
2015) Validation of ground-based microwave radiometer data and its application in verifying atmospheric stability over Mahbubnagar during 2011 monsoon and post-monsoon seasons, Atmospheric instabilities, mainly convection, depend on temperature distribution and moisture availability. The development of convection can often lead to the formation of clouds and precipitation, release of latent heat, etc. The initiation or development of instabilities has to be studied in detail with high-resolution, ground-based instruments such as ground-based microwave radiometric measurements. In this study we evaluated ground-based microwave radiometer data (MWR)-retrieved temperature and relative humidity profiles and compared these to radiosonde observations. Analysis showed that MWR-measured temperature (specific humidity) has a warm (wet) bias below 3 km and cold (dry) bias above that altitude. Correlation of stability indices estimated from radiometer and radiosonde showed fairly good correlation, with a correlation coefficient greater than 0.5 with 95% significance. MWR was then utilized for the verification of atmospheric stability over Mahbubnagar (16°44′ N, 77°59′ E), India, during the second half of the monsoon and start of post-monsoon seasons. Radiometric observations showed strong day-to-day variation of atmospheric parameters as well as thermodynamic indices during the monsoon, which were weak during the post-monsoon season. The seasonal mean of thermodynamic indices and the associated seasonal difference showed that thunderstorm potential is higher during the post-monsoon season over the study site.
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