Sensitivity of NO_x over the Indian Ocean to emissions from the surrounding continents and nonlinearities in atmospheric chemistry responses

Abstract

The sensitivity of the Indian Ocean atmospheric chemistry to continental NO x emissions is examined using a global chemistry‐transport model (MATCH‐MPIC). NO x responds nonlinearly to changes in emissions, since O 3 and OH, which depend on NO x , influence its lifetime. Due to this feedback and the contribution from other NO x sources (e.g., lightning), much of the Indian Ocean lower troposphere (LT) is only weakly sensitive to continental NO x emissions. In contrast to INDOEX (Indian Ocean Experiment) results for aerosols, CO, etc., during the winter monsoon the central Indian Ocean (CIO) is weakly sensitivity to Indian NO x emissions. However, the Bay of Bengal LT is very sensitive to NO x emissions from India (summer) and SE Asia and China (winter). Higher up, NO x over the CIO is most sensitive to African and SE Asian emissions, while the northern regions are influenced by the summer monsoon plume from India, SE Asia and China.