GREENBELT, Md., Aug. 31 (UPI) -- Two destructive natural disasters in 2010 -- one in Russia and one in Pakistan -- were linked by a single meteorological event, a NASA study suggests.
Extreme heat and persistent wildfires in Russia and unusual rainfall in the Indian monsoon region that fueled heavy flooding in Pakistan were both triggered by an abnormal large-scale meteorological event knows as a Rossby wave, NASA said in a release Wednesday.
As Earth spins on its axis, huge rivers of atmospheric air, dubbed Rossby waves, wander around the globe in a westerly direction, and currents in the center of these waves form the jet streams that push weather systems from west to east.
Under normal summertime conditions, the jet stream pushes weather fronts through Eurasia in just four or five days, but in July 2010 a stagnant weather pattern known as a blocking event developed over western Russia. The event divided the jet stream and slowed the Rossby wave, preventing the normal progression of weather systems from west to east.
A large region of high pressure formed over Russia and trapped a hot, dry air mass that turned the region into a tinderbox, while the same blocking pattern created unusual downstream wind patterns over Pakistan bringing monsoon rains and flooding to the region.
"From NASA satellite data and wind analysis, we can clearly see the connection between the two events," William Lau, an atmospheric scientists at NASA's Goddard Space Flight Center in Greenbelt, Md., said. "Think of the atmosphere like a loose membrane. If you push one part up, something else has to come down somewhere else. If you produce a high in one region, you produce a corresponding low in another."