Three NASA satellites are now being used by a professor from the Tel Aviv University to gauge an accurate measure of the pollution levels over our planet’s megacities, the first to provide a comprehensive standardised global testing of pollution levels.
Prof. Pinhas Alpert of Tel Aviv University’s Department of Geophysics and Planetary Sciences and head of the Porter School of Environmental Studies along with graduate student Olga Shvainshteinand and Dr. Pavel Kishcha turned to NASA satellites MODIS-Terra, MODIS-Aqua, and MISR to accurately analyse the level of pollution over 189 megacities.
The megacities are qualified as cities with populations exceeding 2 million, though 58 of these cities actually have populations exceeding 5 million people.
The data gathered from the three NASA satellites provides an accurate survey of aerosol concentrations a few hundred metres above the Earth, sort of like the traditinal Jewish idea of the three-judge panel, according to Professor Alpert.
“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.”
In their study, which was published in the American Journal of Climate Change, Alpert and colleagues found that Northeast China, India, the Middle East, and Central Africa are currently leading in pollution increase, including Bangalore, India, with a 34 percent average increase in aerosol concentration between 2002 and 2010.
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Europe and Northeast and Central North America are seeing the largest decreases in aerosol concentrations overall with cities like Houston seeing a 31 percent decrease over the time period. Curitiba, Brazil saw a 26 percent decrease and Stockholm, Sweden a 23 percent decrease.
The data also showed that some American cities like Portland and Seattle were among those cities which saw increases in pollution levels, but Professor Alpert believes this is a result of the satellites detecting the results of the wildfires that had plagued the region over the period examined. He hopes in the future to develop a method for separating natural causes of pollution from man-made pollutants.