Cirrus detrainment-temperature feedback

Chia Chou and J. David Neelin
Geophys. Res. Lett., 1999.

Paper (PDF 1.4MB).
© Copyright 1999 by the American Geophysical Union.


Abstract In considering the role of cirriform clouds in climate change, it is important to distinguish among the relationships of different high cloud types to large-scale atmospheric dynamics. While cirostratus and cirrocumulus (CsCc) have a clear relation to deep convective sources, the ensemble behavior of cirrus is more subtle. An emperical relation is found between cirrus fraction and deep cloud top temperature that points to detrainment temperature as a dominant factor governing tropical and subtropical cirrus. This cirrus-detrainment-temperature (CDT) relation provides a target for modelers, and suggests an additional cloud-climate feedback. As surface temperatures warm, detrainment temperatures cool as deep cloud top height increases. The CDT relation implies that cirrus fraction increases. Because cirrus are optically thinner than CsCc, the competition between longwave feedbacks and cloud albedo feedbacks leads to a hypothesized positive climate feedback by cirrus fraction.

Citation Chou, C. and J. D. Neelin, 1999: Cirrus detrainment-temperature feedback. Geophys. Res. Lett., 26(9), 1295-1298.