The Impact of Tropical Intraseasonal Variability on the Global Distribution of Precipitation

The effects of tropical intraseasonal variability on the global distribution of precipitation including extremes are studied with the NCAR Community Atmosphere Model, version 5 (CAM5). CAM5 is initially forced with prescribed daily SST (1999-2008) for 10 years, which is considered the control run in the study. Additional experiments are performed with different amplitudes of ERA-Interim diabatic heating values (1999-2008) added to the temperature tendency value of the control run set-up. The diabatic heating is added only between 15S-15N through out the entire zonal region with a meridional Gaussian decay to 20S and 20N. Two separate runs, one with bandpass filtered diabatic heating and another with bandpass filtered data removed from the daily mean diabatic heating values are also run for similar set ups. The major regions of study are the Northern America, South America, Africa, Asia and Australia. The impact of the applied tropical heating forcing is presented as seasonal variability in the regions of extratropics. Rossby-wave mechanisms involved in each case will be elucidated as well.