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Urban pollution above the forest

The Manaus plume can travel 250 km over the forest and increase the region's rainfall

Eduardo CesarThe Manaus plume can travel 250 km over the forest and increase the region’s rainfallEduardo Cesar

By using their cars, the inhabitants of Manaus are changing local rainfall patterns. In February and March 2014, as part of the Green Ocean (GO) Amazon research program, researchers from Brazil and the United States got into a plane and completed 15 fly-overs over the Amazon Forest and the city of Manaus, the capital of Amazonas State in Brazil. They found that the mass of polluted air generated by the city, known as the pollution plume, is able to travel distances of up to 250 kilometers and change rainfall patterns in the forest and in Manaus. Flying at a minimum altitude of roughly 2000 feet, the Gulfstream ARM 1 aircraft, also known as G-1, is owned by the Pacific Northwest National Laboratory (PNNL). The plane zigzagged inside the plume, filmed the clouds ahead, photographed ice crystals, and used the sensors under its wings or in its fuselage to record the amounts of particulate matter, nitrogen oxides, carbon monoxide, and ozone produced by the city, as well as the volatile organic compounds released by the plants in the forest. “We were able to capture the extent and altitude of the Manaus plume, which was an excellent match to our numerical model of chemical transport through the atmosphere,” said Karla Longo, researcher at the National Institute for Space Research (INPE) and coordinator of this part of the project, which is funded by the U.S. Department of Energy. “We also got extensive logistic support from Brazil’s Ministry of Defense and Air Force.” The collected information was compiled into a database and made publicly available through maps and charts on the INPE website.