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 a new study by researchers at Harvard, published in the AGU journal Geophysical Research Letters.
Using 23 years of infrared satellite imagery, global tropical cyclone best-track data, and reanalysis of tropopause temperature, David Romps and Zhiming Kuang found that tropical cyclones contribute a disproportionate amount of the tropical deep convection that overshoots the troposphere and reaches the stratosphere.
Tropical cyclones account for only 7% of the deep convection in the tropics, but 15% of the convection that reaches the stratosphere, they found. The authors 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.
David M. Romps and Zhiming Kuang (2009) Overshooting convection in tropical cyclones. Geophys. Res. Lett. 36, L09804, doi: 10.1029/2009GL037396