Saturday, May 30, 2009

Positive feedback hint between tropical cyclones and global warming

Science Daily: Tropical cyclones could be a significant source of the deep convection that carries moist air upward to the stratosphere, where it can influence climate, according to Harvard University researchers David M. Romps and Zhiming Kuang. Using 23 years of infrared satellite imagery, global tropical cyclone best-track data, and reanalysis of tropopause temperature, the authors found that tropical cyclones contribute a disproportionate amount of the tropical deep convection that overshoots the troposphere and reaches the stratosphere.

Their findings appear in a recent issue of Geophysical Research Letters. Tropical cyclones account for only 7 percent of the deep convection in the tropics, but 15 percent of the convection that reaches the stratosphere, the researchers found. They conclude that tropical cyclones could play a key role in adding water vapor to the stratosphere, which has been shown to increase surface temperatures.

Because global warming is expected to lead to changes in the frequency and intensity of tropical cyclones, the authors believe their results suggest the possibility of a feedback mechanism between tropical cyclones and global climate…..

Tropical cyclone Dominic, January 2009, shot thanks to a vigilant satellite at NASA

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