Maritime NO_x Emissions Over Chinese Seas Derived From Satellite Observations

Abstract

By applying an inversion algorithm to NO_x satellite observations from Ozone Monitoring Instrument, monthly NO_x emissions for a 10 year period (2007 to 2016) over Chinese seas are presented for the first time. No effective regulations on NO_x emissions have been implemented for ships in China, which is reflected in the trend analysis of maritime emissions. The maritime emissions display a continuous increase rate of about 20% per year until 2012 and slow down to 3% after that. The seasonal cycle of shipping emissions has regional variations, but all regions show lower emissions during winter. Simulations by an atmospheric chemistry transport model show a notable influence of maritime emissions on air pollution over coastal areas, especially in summer. The satellite-derived spatial distribution and the magnitude of maritime emissions over Chinese seas are in good agreement with bottom-up studies based on the Automatic Identification System of ships.