November 27, 2012
Researchers Use Satellites To Track Smog From Space
Michael Harper for redOrbit.com — Your Universe Online
As it turns out, measuring pollution from the ground can be a tough task. Smog, in particular, can be hard to track. This thick, dirty cloud is often found over the world´s megacities, with populations over 2 million. Scientists have placed monitoring stations in these cities in an attempt to monitor smog levels, but they aren´t always accurate. The placement of these monitoring stations is crucial, and they aren´t always found in the best locations.
Now, a team from Tel Aviv University´s Department of Geophysics and Planetary Sciences has come up with a way to take a bird´s eye view of global smog by taking to the skies and borrowing data from satellites.
Prof. Pinhas Alpert, graduate student lga Shvainshteinand and Dr. Pavel Kishcha have been studying data from three of NASA´s satellites to gather a comprehensive view of where smog is building up, as well as judge specific cities for how effective their smog reduction efforts have been. This new method has been published in the American Journal of Climate Change and is the first to provide a standardized test for global smog levels. Professor Alpert hopes this method will also help keep developing countries accountable for their smog levels as well as encourage the rest of us to embrace environmentally friendly behaviors.
Professor Alpert likens these three satellites to the Jewish “Three Judge” panel.
“In the Jewish tradition, individual judges don´t decide cases. There must be a minimum of three. You need a majority opinion,” said Prof. Alpert in the statement.
“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,” he explained.
These “imperfect” sensors are 3 aerosol-monitoring satellites: MODIS-Terra, MODIS-Aqua, and MISR. Combined, these 3 satellites have been capturing and gathering data from a few hundred meters about Earth for nearly 10 years.
Prof. Alpert and team studied the smog levels of 189 megacities all over the world, including the largest megacities, such as Mumbai, New York City and Tokyo.
After compiling the data, the team found that Central Africa, Northeast China, the Middle East and India are currently leading the world in pollution increase. Aerosol pollution in particular rose by 34% between 2002 and 2010. Northeast and Central North America, as well as Europe, are seeing some of the greatest pollution decreases according to the team. The South Texas city of Houston was (somewhat remarkably) found to be one of the cleanest megacities in the region, with a 31% decrease between 2002 and 2010. Curitiba, Brazil scored a 26% decrease, while Stockholm, Sweden scored a 23% decrease.
In another somewhat shocking revelation, Professor Alpert and team found that 2 Pacific northwest megacities, Portland, Oregon and Seattle, Washington, saw an increased level in pollution in the same time period. Portland, for example, saw a 52% increase in their pollution levels, while Seattle experienced a 32% increase.
Professor Alpert suspects these numbers might be higher due to the wildfires which affected these areas in between 2002 and 2010. In the future, Prof. Alpert and team hope they can develop a method which will account for natural pollution.