Use of Satellite-Derived Air Pollution Observations to Provide Insight Into the Relationship Between Population, Long-Range Transport and Climate

Several satellite-derived techniques for determining the extent of regional air pollution have been developed. One approach, a unique tool for deriving tropospheric ozone from satellite observations, has recently identified several "hotspot" regions around the globe where high amounts of photochemical smog can be seen. One such area identified is across East Asia, which coincides with the region that is affected by the occurrence of the Atmospheric Brown Cloud phenomenon. The prevalence of air pollution over vast areas of Asia has a significant impact on the health and the quality of life of more than one billion people and likely on the growth and yield of many crops grown in this region. This particular technique has identified a massive pollution cloud over this region that is strongly correlated with the distribution of population in China and northern India. The intensity and extent of the pollution is greatest during the summer months when the generation of photochemical smog is most efficient. When compared with widespread air pollution episodes over the eastern United States, the extent and magnitude of the Asian events are even greater. In addition, the amount of pollution exhibits significant interannual variability and this study shows that this year-to-year variability is closely linked to the phase of the El Ni¤o-Southern Oscillation. This same technique has also shown linkages between transport of air pollution across the North Atlantic and a particular phase of the North Atlantic Oscillation. The consequence of such transport is that it may impact regions downwind and their ability to meet their ozone attainment goals. In addition, we have recently developed an approach to provide 48-hour air quality forecasts of PM 2.5 across the United States utilizing satellite-derived aerosol products from the MODIS (Moderate Resolution Imaging Spectrometer) instrument and meteorological data from the ETA model. Relationships between the movement of high PM events and prevailing meteorology are presented. Both of these state-of-the-art approaches highlight how satellite observations uniquely identify the regional aspect of air pollution, and how such information can be used to study linkages between pollution and climate, and even provide the foundation for air quality forecasts.