NO_x Contribution by Lightning over the Indian Region

摘要

NO_x contribution by lightning over the Indian region covering from 8°-33°N and 73°-86°E has been assessed by using satellite lightning measurement from the Lightning Imaging Sensor (LIS). The lightning data from LIS for 4 year (1998-2001) period are analyzed and partitioned based on the latitude to obtain the differential count [Intra-cloud (IC) and Cloud to ground (CG) flashes]. The total lightning activity during 4 year period by LIS is 1.12x10~7 including 9.4x10~6 IC flashes and 1.8x10~6 CG flashes respectively over the Indian region. The total as well as the differential count is further utilized to estimate total and seasonal NO_x contribution. The results indicate that a lightning NO_x contribution is 0.18 Tg N yr~(-1) over this latitudinal region using the representative contribution value of 6.7x10~(26) NO molecules for each CG and IC flash respectively. Seasonal analysis of NO_x contribution suggests that the maximum contribution of NO_x occurred in the premonsoon and monsoon months (i.e. 0.084 and 0.088 Tg N yr~(-1) respectively). Among the IC and CG flashes, NO_x yield from IC flashes is observed to be significantly higher than the CG flashes contributing nearly 83% and 17% to total NO_x contribution.