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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L15707, doi:10.1029/2007GL029698, 2007

Cloud and radiation budget changes associated with tropical intraseasonal oscillations

Roy W. Spencer

Earth System Science Center, University of Alabama in Huntsville, Huntsville, Alabama, USA


William D. Braswell

Earth System Science Center, University of Alabama in Huntsville, Huntsville, Alabama, USA


John R. Christy

Earth System Science Center, University of Alabama in Huntsville, Huntsville, Alabama, USA


Justin Hnilo

Lawrence Livermore National Laboratory, Livermore, California, USA


Abstract

We explore the daily evolution of tropical intraseasonal oscillations in satellite-observed tropospheric temperature, precipitation, radiative fluxes, and cloud properties. The warm/rainy phase of a composited average of fifteen oscillations is accompanied by a net reduction in radiative input into the ocean-atmosphere system, with longwave heating anomalies transitioning to longwave cooling during the rainy phase. The increase in longwave cooling is traced to decreasing coverage by ice clouds, potentially supporting Lindzen's “infrared iris” hypothesis of climate stabilization. These observations should be considered in the testing of cloud parameterizations in climate models, which remain sources of substantial uncertainty in global warming prediction.

Received 15 February 2007; accepted 16 July 2007; published 9 August 2007.

Keywords: tropical; climate; feedbacks.

Index Terms: 3310 Atmospheric Processes: Clouds and cloud feedbacks; 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 3359 Atmospheric Processes: Radiative processes; 3360 Atmospheric Processes: Remote sensing; 3374 Atmospheric Processes: Tropical meteorology.

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 352330 bytes)

Citation: Spencer, R. W., W. D. Braswell, J. R. Christy, and J. Hnilo (2007), Cloud and radiation budget changes associated with tropical intraseasonal oscillations, Geophys. Res. Lett., 34, L15707, doi:10.1029/2007GL029698.