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Dennis L. Hartmann
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Marc L. Michelsen
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It is shown that the negative correlation between cloud-weighted sea surface temperature (SST) and high cloud fraction discussed recently by Lindzen et al. results from variations in subtropical clouds that are not physically connected to the deep convection near the equator. A negative correlation between cloud-weighted SST and average cloud fraction results from any variation in cloud fraction over the areas with lower SSTs within the domain of interest. Therefore, this correlation is not evidence that tropical cloud anvil area is inversely proportional to sea surface temperature and should not be used to infer the existence of a negative feedback in the climate system.

Department of Atmospheric Sciences, University of Washington, Seattle, Washington

CORRESPONDING AUTHOR: Dennis L. Hartmann, Department of Atmospheric Sciences, University of Washington, 710 Atmospheric Sciences/Geophysics Building, Box 351640, Seattle, W A 98915-1640, E-mail: dennis@atmos.washington.edu

It is shown that the negative correlation between cloud-weighted sea surface temperature (SST) and high cloud fraction discussed recently by Lindzen et al. results from variations in subtropical clouds that are not physically connected to the deep convection near the equator. A negative correlation between cloud-weighted SST and average cloud fraction results from any variation in cloud fraction over the areas with lower SSTs within the domain of interest. Therefore, this correlation is not evidence that tropical cloud anvil area is inversely proportional to sea surface temperature and should not be used to infer the existence of a negative feedback in the climate system.

Department of Atmospheric Sciences, University of Washington, Seattle, Washington

CORRESPONDING AUTHOR: Dennis L. Hartmann, Department of Atmospheric Sciences, University of Washington, 710 Atmospheric Sciences/Geophysics Building, Box 351640, Seattle, W A 98915-1640, E-mail: dennis@atmos.washington.edu
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