Changes in SO2 and NO2 Pollution over the Past Decade Observed by Aura OMI

Abstract:

The Ozone Monitoring Instrument (OMI), a NASA partnership with the Netherlands and Finland, flies on the EOS Aura satellite and uses reflected sunlight to measure two critical atmospheric trace gases, nitrogen dioxide (NO₂) and sulfur dioxide (SO₂), characterizing daily air quality. Both gases and the secondary pollutants they produce (particulate matter, PM2.5, and tropospheric ozone) are among USEPA designated criteria pollutants, posing serious threats to human health and the environment (e.g., acid rain, plant damage, and reduced visibility).

A new generation of the OMI standard SO₂ and NO₂ products (based on critically improved DOAS spectral fitting for NO₂ and innovative Principal Component Analysis method for SO₂) provides a valuable dataset for studying anthropogenic pollution on local to global scales. Here we highlight some of the OMI observed long-term changes in air quality over several regions.

Over the US, average NO₂ and SO₂ pollution levels have decreased dramatically as a result of both technological improvements (e.g., catalytic converters on cars) and stricter regulations of emissions. We see continued decline in NO₂ and SO₂ pollution over Europe. Over China OMI observed a ~ 60% increase in NO₂ pollution between 2005 and 2013, despite a temporary reversal of the growing trend due to both 2008 Olympic Games and the economic recession in 2009. Chinese SO₂ pollution seems to have stabilized since peaking in 2007, probably due to government efforts to curb SO₂ emissions from the power sector. We have also observed large increases in both SO₂ and NO₂ pollution particularly in Eastern India where a number of new large coal power plants have been built in recent years. We expect that further improvements in the OMI NO₂ and SO₂ products will allow more robust quantification of long-term trends in local to global air quality.