Using Earth Observations to Monitor City-wide Air Quality

Air pollution has adverse effects on human health, but is challenging to routinely monitor in cities. Earth observations of atmospheric composition provide complete coverage of cities, but require validation with ground-based observations and interpretation with a detailed chemical transport model (CTM). We present first steps to use long-term (2005-2017) Earth observations to estimate trends in air pollution in 4 cities at different stages of development: London (developed) and Birmingham (urban renewal) in the UK, and New Delhi (semi-developed) and Kanpur (developing) in India. We estimate the same decline in NO₂ in London and Birmingham of 3.4% a^-1 from Ozone Monitoring Instrument (OMI) tropospheric columns of NO₂. This is a steeper trend than is estimated with surface NO₂ observations in London (-1) and with the UK Environment Agency air quality model for Birmingham (-1). We will apply the same approach to New Delhi and Kanpur and use a CTM to aid in interpreting NO_x emission trends and discrepancies between column and surface trends.