FOR MUCH OF THE YEAR THE TROPICAL EAST PACIFIC IS DOMINATED BY A DRY COLD TONGUE ALONG THE EQUATOR AND A BAND OF HEAVY PRECIPITATION NORTH OF THE EQUATOR IN THE INTERTROPICAL CONVERGENCE ZONE (ITCZ). HOWEVER THE EAST PACIFIC EXPERIENCES LARGE VARIATIONS IN PRECIPITATION BOTH SEASONALLY AND INTERANNUALLY ESPECIALLY WHEN A DOUBLE ITCZ STRADDLES THE EQUATOR DURING SPRING AND DURING EL NINO EVENTS WHEN THE COLD TONGUE DISAPPEARS. THE VERTICAL HEATING ASSOCIATED WITH THESE PRECIPITATION CHANGES ALSO VARIES WITH BOTTOM-HEAVY HEATING PREDOMINANT IN WINTER BOTH SHALLOW AND DEEP HEATING OCCURRING DURING SUMMER AND A LACK OF LOW-LEVEL HEATING DURING SPRING AND IN EL NINO EVENTS (I.E. WHEN SEA SURFACE TEMPERATURE GRADIENTS ARE WEAKEST). GENERAL CIRCULATION MODELS (GCMS) PRESENT LARGE BIASES IN PRECIPITATION IN THE EAST PACIFIC ESPECIALLY DURING SPRINGTIME AND EL NINO EVENTS LEADING TO INACCURACIES IN THE REPRESENTATION OF GLOBAL TELECONNECTIONS TIED TO TROPICAL VARIABILITY. A POTENTIALLY SIGNIFICANT ASPECT OF PRECIPITATION VARIABILITY IN THE EAST PACIFIC IS VIA TROPICAL PROPAGATING MODES SUCH AS CONVECTIVELY COUPLED EQUATORIAL WAVES EASTERLY WAVES AND THE MADDEN- JULIAN OSCILLATION. THESE MODES OCCUR IN THE EAST PACIFIC THROUGHOUT THE YEAR BUT THEIR RELATIVE IMPORTANCE TO SEASONAL AND INTERANNUAL PRECIPITATION AND CIRCULATION VARIATIONS REMAINS HIGHLY UNDERSTUDIED. THIS PROJECT AIMS TO IMPROVE THE UNDERSTANDING AND PREDICTION OF CONVECTIVE SYSTEMS ASSOCIATED WITH TROPICAL PROPAGATING MODES IN THE EAST PACIFIC USING NASA'S TROPICAL RAINFALL MEASURING MISSION (TRMM) AND GLOBAL PRECIPITATION MEASUREMENT (GPM) SATELLITES AND NASA'S MERRA2 REANALYSIS AS THE MAIN TOOLS. THE FIRST GOAL IS TO CHARACTERIZE THE DOMINANT TROPICAL PROPAGATING MODES IN THE EAST PACIFIC THROUGHOUT THE YEAR AND THE MECHANISMS THAT EXCITE THEM AND TO DETERMINE THE INTERANNUAL VARIATION OF THESE TROPICAL PROPAGATING MODES VIA EL NINO OR EXTRATROPICAL OSCILLATIONS USING WAVENUMBER-FREQUENCY SPECTRA FOURIER FILTERS EMPIRICAL ORTHOGONAL FUNCTIONS AND LINEAR REGRESSIONS. WE ARE ALSO GOING TO ASSESS THE SYNOPTIC VARIABILITY OF MERRA2 AGAINST GROUND AND SATELLITE DATA AND ANALYZE THE MERIDIONAL CIRCULATION OF THE EAST PACIFIC INTERACTING WITH TROPICAL PROPAGATING MODES USING GCMS FROM CMIP6 (INCLUDING THE NASA GISS MODEL) AND OTHER MODERN REANALYSIS DATASETS.