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AGU: Geophysical Research Letters

 

Keywords

  • Pacific warm pool
  • cloud
  • feedback
  • geostationary satellite
  • longwave

Index Terms

  • 0321 - Cloud/radiation interaction
  • 3310 - Clouds and cloud feedbacks
  • 3360 - Remote sensing
  • 3371 - Tropical convection

Paper in Press

GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2012GL052700

The observed variation in cloud-induced longwave radiation in response to sea surface temperature over the Pacific warm pool from MTSAT-1R imagery

Key Points
  • Cloud's noise effect on SST hinders estimation of the radiative feedback.
  • Clear-sky SST helps meaningful estimation of the longwave response to SST change.
  • Clouds over the Pacific warm pool have longwave cooling effect for increased SST.

Authors:

Heeje Cho

Chang-Hoi Ho

Yong-Sang Choi

This study investigated variations in outgoing longwave radiation (OLR) in response to changes in sea surface temperature (SST) over the Pacific warm pool area (20{degree sign}N-20{degree sign}S, 130{degree sign}E-170{degree sign}W). OLR values were obtained from recent (January 2008-June 2010) geostationary window channel imagery at hourly resolution, which resolves processes associated with tropical convective clouds. We used linear regression analysis with the domain-averaged OLR and SST anomalies (i.e., ΔOLR, ΔSST; deviations from their 90-day moving averages). Results show that the regression slope appears to be significant only with SST least-affected by cloud radiative forcing, for which SST needs to be obtained as daily average over cloud-free regions (ΔSSTclear). The estimated value of ΔOLR/ΔSSTclear is 15.72 W m−2 K−1, indicating the presence of strong longwave radiation in response to surface warming. This atmospheric cooling effect is found to be primarily associated with reduced areal coverage of clouds (−14.4% K−1).

Received 14 June 2012; accepted 17 August 2012.

Citation: Cho, H., C.-H. Ho, and Y.-S. Choi (2012), The observed variation in cloud-induced longwave radiation in response to sea surface temperature over the Pacific warm pool from MTSAT-1R imagery, Geophys. Res. Lett., doi:10.1029/2012GL052700, in press.