Identifying changes in convective air circulation
The Hadley cells form the planetary overturning circulation in the tropical atmosphere. In a Hadley cell, air rises from near the equator at the surface to the upper troposphere, moves poleward until about 30° in latitude, then descends into the subtropics before moving equatorward along the Earth's surface. Recent observations and simulations with climate models suggest that the north-south extent of the Hadley cells may be increasing, which may dramatically alter climate on regional scales. Korty and Schneider (2008) analyzed dynamical mechanisms responsible for terminating the Hadley cells in the subtropics. They suggest that Hadley cells terminate where eddies generated in the extratropics become so deep that they reach the upper troposphere. At the latitude where this occurs, the direction of the momentum flux carried by the eddies changes sign; the tropical Hadley cells give way to the extratropical Ferrel cells. The authors show how the atmospheric thermal structure determines this latitude in dry atmospheres. It remains to be investigated how latent heat release in phase changes of water influences the Hadley cell termination.
- Article Category
- Atmospheric Science
Extent of Hadley circulations in dry atmospheres
- First Published:
- | DOI:
Eos.org: Earth & Space Science News
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