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Riehl and Malkus Revisited: The Role of Cloud-Radiative Effects
  • Michael Robert Needham,
  • David Allan Randall
Michael Robert Needham
Colorado State University

Corresponding Author:m.needham@colostate.edu

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David Allan Randall
Colorado State University
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The intertropical convergence zone (ITCZ) exports energy and imports moisture in a way that has been well-understood for decades. By analyzing a set of uniform, non-rotating aquaplanet simulations we show that energy export and moisture convergence are general characteristics of warm humid regions, and not just of the ITCZ. Using an analysis method based on the column relative humidity, we find that the absorption of longwave radiation by clouds provides the necessary energy source to balance the horizontal energy export out of humid regions. The longwave absorption also induces a thermally direct circulation which lifts water vapor and leads to low-level moisture convergence into regions that are already quite humid. This feedback is similar to other cloud-longwave feedbacks which have been previously studied.
27 Aug 2021Published in Journal of Geophysical Research: Atmospheres volume 126 issue 16. 10.1029/2021JD035019