CONVECTION IS THE MAIN ENGINE FOR ATMOSPHERE HEAT AND MASS TRANSPORT. IT IS RESPONSIBLE FOR A LARGE PORTION OF TROPICAL AND MIDLATITUDE WARM SEASON SURFACE RAINFALL. A SINGLE CONVECTIVE CELL GENERALLY HAS A HORIZONTAL SCALE OF 10 TO 20 KM WITH A LIFE-SPAN OF 1 TO 2 HOURS. THESE CELLS ARE RESPONSIBLE FOR LIFTING THE MAJORITY OF HYDROMETEOR PARTICLES TO THE MID- TO UPPER TROPOSPHERE AND FOR GENERATING THE BULK OF SURFACE RAINFALL. THIS STUDY FOCUSES ON THE CONVECTIVE CELLS THAT ARE IDENTIFIED USING THE DUAL-FREQUENCY PRECIPITATION RADAR (DPR) AND THE GPM MICROWAVE IMAGER (GMI) ONBOARD THE GLOBAL PRECIPITATION MEASUREMENT (GPM) CORE SATELLITE. BASED ON THE ASSUMPTION THAT DEEP CONVECTION HAS STRONG UPDRAFTS AND IS ABLE TO LIFT LARGE HYDROMETEOR PARTICLES TO HIGH ALTITUDES SEVERAL PARAMETERS ARE PROPOSED TO IDENTIFY CONVECTIVE CELLS INCLUDING KU-BAND RADAR REFLECTIVITY KU- AND KA-BAND DIFFERENTIAL REFLECTIVITY AND BRIGHTNESS TEMPERATURES AND POLARIZATIONS AT 89 GHZ AND 166 GHZ. THE GODDARD CUMULUS ENSEMBLE (GCE) MODEL WITH A SPECTRAL BIN MICROPHYSICAL SCHEME COMBINED WITH TWO DIFFERENT SATELLITE SIMULATORS WILL BE USED TO HELP INTERPRET GPM OBSERVED CONVECTIVE CORE STATISTICS AND EXTRAPOLATE THEIR PHYSICAL MEANING. ADDITIONALLY COMPARISONS BETWEEN GPM OBSERVATIONS AND MODEL SIMULATIONS WILL SERVE TO VALIDATE THE CLOUD-RESOLVING MODEL S PHYSICS AS WELL AS TO PROVIDE MUCH NEEDED CONSTRAINTS ON HYDROMETEOR SCATTERING PROPERTIES NECESSARY FOR A SATELLITE SIMULATOR. HERE GPM OBSERVATIONS SERVE AS AN ANCHOR TO IMPROVE BOTH CLOUD SIMULATIONS AND MICROWAVE RADIATIVE TRANSFER CALCULATIONS. THE OBJECTIVES OF THE PROPOSED STUDIES ARE: 1). TO EXPERIMENT WITH AND EVALUATE THE EFFECTIVENESS OF DIFFERENT METHODS FOR IDENTIFYING CONVECTIVE CELLS IN GPM OBSERVATIONS. THESE METHODS WILL INCLUDE COMBINATIONS OF ALL GPM INSTRUMENTS THE USE OF ONLY DPR OBSERVATIONS AND ONLY GMI OBSERVATIONS. THE LAST TWO METHODS COULD POTENTIALLY PROVIDE USEFUL INFORMATION FOR FUTURE SATELLITE MISSIONS. 2). TO DERIVE CHARACTERISTICS OF AND GAIN BETTER INSIGHT ABOUT ATMOSPHERIC CONVECTION AND ITS VARIABILITY. GPM DATA ANALYSIS WILL FOCUS ON IDENTIFYING ACTIVE CONVECTIVE CELLS AND STUDY THE RANGES OF CONVECTION VARIATIONS IN DIFFERENT METEOROLOGICAL AND GEOPHYSICAL CONDITIONS. STATE-OF-THE-ART CLOUD-RESOLVING MODELS AND SATELLITE SIMULATORS WILL BE USED TO HELP DESIGN DATA STRATIFICATION STRATEGIES AND INTERPRET OBSERVED STATISTICS. 3). TO USE GPM OBSERVED CONVECTION STATISTICS TO VALIDATE AND IMPROVE CLOUD-RESOLVING MODEL SIMULATIONS FOCUSING ON ICE-PHASE MICROPHYSICAL PROCESSES. THIS OBJECTIVE IS AN EXTENSION OF OUR CURRENT STUDY THAT FOCUSES ON THE TRAILING STRATIFORM REGION IN MESOSCALE CONVECTIVE SYSTEMS (MCSS). IN THE PROCESS OF ACCOMPLISHING THESE OBJECTIVES WE WILL ALSO BE ABLE TO ADD TO THE ABILITY TO BOTH THE SPECTRAL BIN MICROPHYSICAL SCHEME AND THE RADIATIVE TRANSFER MODEL SIMULATIONS. FOR THE SPECTRAL BIN SCHEME WE WILL ADD PREDICTIONS OF AXIS RATIOS FOR PRISTINE ICE CRYSTAL PARTICLES. FOR THE RADIATIVE TRANSFER MODEL WE CAN PROVIDE BETTER CONSTRAINTS ON PARTICLE SIZES SHAPES AND MOST IMPORTANTLY PARTICLE ORIENTATIONS INSIDE TURBULENT CONVECTIVE CORES. BOTH IMPROVEMENTS WILL HELP IMPROVE BOTH LATENT HEATING AND SURFACE RAIN RETRIEVALS.