92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012: 9:30 AM
Tropical Clouds and Circulation Changes During Recent El Niņos
Room 354 (New Orleans Convention Center )
Hui Su, JPL, Pasadena, CA; and J. H. Jiang

Changes in tropical clouds, cloud radiative forcing (CRF) and atmospheric circulation exhibit distinctly different characteristics during the 2009-10 Central Pacific-El Niņo and 2006-07 Eastern Pacific-El Niņo, based on the analysis of CloudSat/CALIPSO and reanalysis data. The 2009-10 El Niņo shows a strengthening of tropical circulation, increased high (low) clouds in extremely strong ascending (descending) regimes and decreased mid-to-high clouds in a broad range of moderate circulation regimes, resulting in a reduction of tropical-mean mid-to-high clouds accompanied by an increase of low clouds below 1 km and an increase of thin cirrus above 14 km. The net tropical-mean CRF anomaly at the top-of-the-atmosphere (TOA) is about 0.6-0.7 W/m2 cooling. The 2006-07 El Niņo shows nearly opposite tropical-mean cloud and circulation changes, and the tropical-mean TOA net CRF is 0.2-0.5 W/m2 warming. Our study highlights the importance of SST anomaly pattern in determining the tropical-mean cloud response and their radiative forcing.

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