Observational evidence against strongly stabilizing tropical cloud feedbacks. Issue 3 (8th February 2017)

• Record Type: Journal Article
• Authors: Williams, Ian N.; Pierrehumbert, Raymond T.
• Is Part Of: Geophysical research letters. Volume 44:Issue 3(2017)
• Page Start: 1503
• Page End: 1510
• Publication Date: 2017-02-08
• Subjects: tropical -- cloud -- feedback -- deep convection -- remote sensing -- tropical circulation; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL072202
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We present a method to attribute cloud radiative feedbacks to convective processes, using subcloud layer buoyancy as a diagnostic of stable and deep convective regimes. Applying this approach to tropical remote sensing measurements over years 2000–2016 shows that an inferred negative short‐term cloud feedback from deep convection was nearly offset by a positive cloud feedback from stable regimes. The net cloud feedback was within statistical uncertainty of the National Center for Atmospheric Research Community Atmosphere Model (CAM5) with historical forcings, with discrepancies in the partitioning of the cloud feedback into convective regimes. Compensation between high‐cloud responses to tropics‐wide warming in stable and unstable regimes resulted in smaller net changes in high‐cloud fraction with warming. In addition, deep convection and associated high clouds set in at warmer temperatures in response to warming, as a consequence of nearly invariant subcloud buoyancy. This invariance further constrained the magnitude of cloud radiative feedbacks and is consistent with climate model projections. Key Points: Observations provide evidence against strongly stabilizing tropical cloud feedbacks Compensation between feedbacks in stable and deep convective regimes resulted in a small net feedback consistent with climate models High clouds decrease with warming in regions of deep convection but increase elsewhere, leading to smaller changes in high‐cloud fraction