AGU: Geophysical Research Letters

 

Editors' Highlight

Typhoons and hurricanes are the dominant causes of mixing between the troposphere and the stratosphere

Deep air convection influences climate through injecting water vapor–rich, ozone-poor air from the Earth's near surface to the upper troposphere and lower stratosphere and displacing water vapor–poor, ozone-rich air downward. However, the mechanisms that drive this convection are poorly understood, especially in the tropics where instead of being marked by a sharp transition in temperature, the boundary between the troposphere and the stratosphere is a diffuse region of nearly constant temperature. Rossow and Pearl (2007) conducted a 22-year survey of tropical convection using subsets of data from the International Satellite Cloud Climatology Project. The authors show that deep convection occurs mostly in larger, more organized convective systems but that smaller, unorganized convective systems rarely penetrate into the stratosphere. Durations of penetration are longest for the larger systems, such as hurricanes and typhoons, which generally exceed 1 day. The authors suggest that the role of tropical storms should be examined more closely, since though intermittent, they dominate stratosphere-troposphere exchanges. Further, obtaining adequate statistics on stratosphere-troposphere mixing will rely on generating and maintaining long-term data records.

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