Abstract:
In order to further study possible influences of the photocatalytic reaction on the formation of O
3 and O
3 valley in the summer over the Tibetan Plateau, NO
2 VCD, O
3 total column and O
3 profiles from OMI and OTD (Optics Transient Detection)/LIS (Lightning Imaging Sensor) total lightning data are used to investigate the spatial and temporal distributions characteristics of TOC and NO
2 VCD, the correlation between lightning and NO
2 VCD, the vertical distribution of O
3 and its relationship with LNO
x in the Tibetan Plateau and the Yangtze River Delta. Results in the two regions, which are located at the similar latitudes, are compared and analyzed. It is found that the O
3 valley over the Tibetan Plateau mainly appears in the summer and autumn, and its TOC value is about 10-15 DU (Dobson unit) lower than that over the Yangtze River Delta. The NO
2 VCD over the Tibetan Plateau is relatively small, and exhibits a temporal distribution characteristic of low in the summer and high in the winter. The total concentration of O
3 in the Tibetan Plateau generally decreases in the summer due to the effect of the South Asia high. However, due to the influence of strong thunderstorms, the concentration of LNO
x in the upper troposphere increases and can be transported to the top of the troposphere by strong ascending flows, which subsequently increases the concentration of O
3 by photochemical reaction. Thereby, the O
3 concentration difference between the Tibetan Plateau and the same latitude region is reduced and the decrease of the total O
3 concentration slows down, which inhibits further deepening of the O
3 valley in the Tibetan Plateau in the summer.