Professor Pinhas Alpert at Tel Aviv University’s Department of Geophysics and Planetary Sciences is utilizing the sensors on three orbiting satellites to get a better understanding of the pollution levels in the world's megacities, or those with a population of 2 million or more.
The professor and his team tapped sensor technology aboard NASA's MODIS-Terra, MODIS-Aqua, and MISR satellites to analyze aerosol concentrations a few hundred meters above 189 of the largest cities. All three satellites are being used in the study in order to verify the data coming back.“In the Jewish tradition, individual judges don’t decide cases. There must be a minimum of three. You need a majority opinion,” he says. “By merging the data from three imperfect sensors, their flaws are mostly counterbalanced. In cases where the three sensors show differing signs of pollution levels, more research is required.”
The sensors have picked up some interesting data. Not surprisingly, developing regions in Northeast China, India, the Middle East, and Central Africa currently have seen the greatest growth in aerosol concentrations, with Bangalore, India leading all of the cities with a huge 34 percent average increase between 2002 and 2010. Europe and Northeast and Central North America have seen the largest decreases. Houston was the city with the largest decline in aerosol concentrations, dropping 31 percent between 2002 and 2010.
While much of America was seeing decreases, Portland and Seattle saw increases in aerosol concentrations, but Alpert and his colleagues think those results were likely due to a spate of wildfires during the time period. The researchers are hoping to develop a system for separating naturally-caused air pollution and man-made air pollution.