资源环境科技发展态势分析平台

In this article, we investigate indicators for lightning activity by analysing the data of surface heat flux, Bowen ratio (ratio of sensible to latent heats) and cloud base height for a period of 16years (1998-2013) over Indo-Gangetic Plain (IGP) (25 degrees-27 degrees N, 80 degrees-88 degrees E), Indian land excluding IGP (8 degrees-36 degrees N, 68 degrees-98 degrees E) and 10years (2000-2009) over Indian seas [Arabian Sea (5 degrees-20 degrees N, 65 degrees-80 degrees E)+Bay of Bengal (5 degrees-20 degrees N, 80 degrees-98 degrees E)]. Lightning activity varies with the surface heat flux, Bowen ratio and cloud base height over India. Over Indian land, annual lightning flash counts are found to be more by 32 and 24% than those over IGP and Indian seas, respectively. Total heat flux (sensible+latent) and lightning flash counts show a strong correlation coefficient of 0.75 for Indian land and 0.73 for IGP relative to that of Bowen ratio with lightning flash count (0.63 for Indian land and 0.19 for IGP). Hence, the total heat flux represents the best parameter for describing lightning activity over IGP and Indian land. Bowen ratio 1 in pre-monsoon increases lightning flash counts over IGP and Indian land. Cloud base height (a measure of moisture) and lightning flash counts show values in the order as Indian land>Indian seas>IGP. Geographic asymmetry of Indian land, IGP and Indian seas drive the continental and sea surface-atmosphere interactive processes that corroborate: (1) asymmetric synoptic scale delivery of moisture to Indian land and IGP from Indian seas revises the Bowen ratio, cloud base height and lightning activity, (2) increase in lightning activity with the total heat flux over Indian land and (3) enhance the lightning activity with the cloud base height/liquid condensation level.