Figure: Longitude–pressure cross sections of percentage NOx anomalies averaged for the monsoon season (JJAS) obtained from (a) Ind38 (averaged over 8–35ºN), (b) Ind73 (averaged over 8–35ºN), and (c) Chin73 (averaged over 20–45ºN) simulations.
Influence of enhanced Asian NOx emissions on ozone in the Upper Troposphere and Lower Stratosphere (UTLS) in chemistry climate model simulations:
In this paper we investigate the potential impact of enhanced anthropogenic nitrogen oxide (NOx) emissions on the distribution of ozone in the UTLS using the fully-coupled aerosol chemistry climate model, ECHAM5-HAMMOZ. We performed anthropogenic NOx emission sensitivity experiments over India and China. In these simulations, covering the years 2000-2010 anthropogenic NOx emissions have been increased by 38% over India and by 73% over China. These emission increases are comparable to the observed linear trends of 3.8% per year over India and 7.3% per year over China during the period 2000 to 2010. These elevated NOx emissions produce significant warming over the Tibetan Plateau and increase precipitation over India via strengthening of the monsoon Hadley circulation. However increase in NOx emissions over India by 73% (similar to the observed increase over China), results in large ozone production over the Indo Gangetic plain and Tibetan Plateau. The higher ozone concentrations, in turn, induce a reversed monsoon Hadley circulation and negative precipitation anomalies over India. The associated subsidence suppresses vertical transport of NOx and ozone into the ASM anticyclone. [Roy et al., Atmospheric Chemistry and Physics, Vol. 17, 1297-1311, 2017]