Lightning Detection Systems (LDS) have a vital role in the real-time identification of the location of lightning strikes for the purpose of weather forecasting and issuing warning with sufficient lead time for safe operations. The spatial and temporal distribution of lightning, formulated using LDS observations, can be an objective input to infer and refine the climatology of Thunderstorm (TS) over a region. This study uses the data of Indian Air Force (IAF) LDS network to prepare climatological plots of lightning over India and to formulate location-specific TS guidance for a total of 12 Indian airports. The analysis of climatological plots reveals that there is a distinct warm-season preponderance of lightning strikes over Indian subcontinent, with pre-monsoon months receiving the maximum lightning. The most probable time of occurrence being 1200-1400 UTC during all the seasons across the country. Location-specific TS guidance not only signifies the most probable direction of occurrence of TS with respect to the airport, but also clearly brings out the favourable direction of movement. Hence, the same can be judiciously used as nowcasting aid coupled with actual LDS and Doppler Weather Radar (DWR) observations. Further, the characteristics features of lightning, like surges in flash rate, can be objectively used to define a predictor for nowcasting severe weather associated with a TS cloud. The study of these surges in lightning flash rate visa vis occurrence of Strong Surface Winds (SSW) > 60 kmph over Delhi National Capital Region(NCR), indicated that there is an increase in the number of lightning flashes prior to the occurrence of SSW. 77.5 % occurrences are preceded by surges in flash rate within 45 minutes of the occurrence of SSW, however, the probability of detection of the event with a lead time of 15 to 45 minutes is around 71%.
Time and intensity specific very short-term forecasting or nowcasting is the biggest challenge faced by an Aviation Meteorologist. Ground-based Microwave Radiometer (MWR) has been used for nowcasting convective activity and it was established that there is a good comparison between thermodynamic parameters derived from MWR and GPS radiosonde observations, indicating that MWR observations can be used to develop techniques for nowcasting severe convective activity. In this study, efforts have been made to bring out the efficacy of MWR in nowcasting thunderstorms and fog. Firstly, the observations of MWR located at Palam, New Delhi, India have been compared with the nearest radiosonde (RS) data to ascertain the variation in respective profiles. Large differences were found in Relative Humidity (RH) whereas temperatures from MWR were found to be close to RS observed temperature upto 3.5 Km. Subsequently, the scattered plots and correlation coefficient of thermodynamic indices / parameters indicated that most of the parameters are either not correlated or have moderate correlation only for 1200 UTC profiles. The superepoch technique of lagged composite for various thermodynamic indices / parameters to obtain a combined picture of all the thunderstorm and dense fog cases on the time series could not determine any pattern to predict thunderstorm and dense fog with lead time of 2-4 hours. MWR profile for a case of occurrence of thunderstorm was analyzed. No significant variation was observed in most of the indices (as calculated from MWR observed parameters) prior to the occurrence of thunderstorm. RH at freezing level and between 950 and 700 hPa levels were the only parameters which increased four hours prior to the occurrence.
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