Using CERES SYN Product to Investigate the Diurnal Cycle

The diurnal cycle of precipitation is poorly represented in climate models. As a result, models likely misrepresent the diurnal cycle of cloud types and the associated cloud radiative effects (CREs). This effect can produce instantaneous errors in the shortwave CRE exceeding -100 W m-2 for an error in the time of convective maximum of only 2 hours. This represents the need to characterize the diurnal cycle of cloud types and CREs, in a manner adequate to test climate models. The Cloud and Earth's Radiant Energy System (CERES) provides a Synoptic (SYN) product available at 3-hourly intervals including all sky and clear sky top of atmosphere, surface, and atmospheric fluxes and cloud properties. In this research, we use the CERES SYN data product to provide a diurnal cycle composite of tropical radiative fluxes. Further, the diurnal cycle of CERES SYN radiative fluxes and cloud properties will be sorted into dynamical regime using 500-hPa vertical velocities from the ECMWF interim reanalysis to provide a meaningful comparison with climate models.