Rapid growth of NOx emissions in India observed from Space

Since the last decade, India has encountered severe problems in air quality and became the most air polluted country in the world.  With satellite observations, we can monitor the changes of NO2 column concentrations in India. However, the information on emissions is very limited. In this study, we use the KNMI DECSO (Daily emission Estimates constrained by Satellite Observation) algorithm to estimate NOx emissions from OMI observations from 2007 to 2018. The results show that NOx emissions have increased by about 40% in the last 12 years. We compare NOx emissions from DECSO and the HTAP bottom-up NOx emissions with the location and capacity of power plants in India. The comparison between DECSO and HTAP shows that the emissions estimated from satellite are more accurate on spatial and temporal scale. We also run the CHIMERE v2013 model with emissions from DECSO and HTAP respectively and compare the model simulations with NO2 in-situ measurements of the Indian national network. The comparison shows that model simulation with DECSO has lower bias and better correlation with in-situ observations than that with HTAP.