EFFECTS OF LONGWAVE CLOUD RADIATIVE FORCING ANOMALIES ON THE ATMOSPHERIC RESPONSE TO EQUATORIAL PACIFIC SEA-SURFACE TEMPERATURE ANOMALIES

The latest version of the National Center for Atmospheric Research com munity climate model (CCM2) has been used to investigate cloud radiati ve forcing (CRF) anomalies associated with equatorial Pacific sea surf ace temperature (SST) anomalies and the effects of the longwave CRF (L WCRF) anomalies on the atmospheric response to the SST anomalies. The SST anomalies cause large CRF anomalies, both longwave and shortwave, as well as latent heat anomalies at low latitudes on a global scale. T he relative magnitude of the simulated longwave and shortwave CRF anom alies is consistent with the result of the Earth Radiation Budget Expe riment (ERBE), implying that cloud height and cloud radiative properti es such as emissivity and reflectivity are well simulated by the model . The LWCRF anomaly strongly enhances the precipitation anomaly in the whole tropical belt. The positive (negative) LWCRF anomaly warms (coo ls) the troposphere and destabilizes (stabilizes) the upper tropospher e. The LWCRF anomaly enhances the Southern Oscillation and the related Walker circulation anomaly. The effects of the LWCRF anomaly are esse ntial to the northern hemispheric extratropical circulation anomaly, t he Pacific/North American pattern.