GGrantIndex
← Search

VALIDATION EFFORTS HAVE BEEN INTEGRAL COMPONENTS OF SATELLITE MISSIONS IN ORDER TO PROVIDE USERS WITH NOT ONLY THE DESIRED PRODUCTS BUT ALSO THE NECESSARY DATA QUALITY INFORMATION. THIS STRATEGY IMPLICITLY ASSUMES THAT VALIDATION STATISTICS ARE GENERALLY REPRODUCIBLE FORM ONE REGION TO ANOTHER SO THAT A FEW VALIDATION EFFORTS ARE ENOUGH TO FULLY CHARACTERIZE PRODUCTS. UNFORTUNATELY WITH PASSIVE MICROWAVE RAINFALL ESTIMATES THE INFORMATION CONTENT IS LIMITED AND VALIDATION RESULTS OFTEN RETAIN DISTINCT REGIONAL DIFFERENCES. WELL CORRELATED AND NEARLY UNBIASED RESULTS IN THE CENTRAL UNITED STATES FOR INSTANCE CAN BECOME NEGATIVELY BIASED WITH MUCH POORER CORRELATIONS WHEN THE SAME ALGORITHM IS APPLIED OVER SOUTH KOREA. HERE WE ATTACK THIS PROBLEM SPECIFICALLY FOR THE GPROF ALGORITHM ALTHOUGH SOME OF THE METHODS ARE LIKELY GENERALIZABLE TO OTHER RAINFALL SENSORS AND PRODUCTS. BECAUSE REGIONAL PROBLEMS ARE CAUSED NEITHER BY RANDOM OR SYSTEMATIC ERRORS BUT RATHER BY REGIME DEPENDENT VARIATIONS IN THE CLOUD SYSTEMS BIASES AND UNCERTAINTIES MUST ALSO BE FRAMED IN THE REGIME FRAMEWORK. ON AN HOURLY BASIS FOR INSTANCE THE DIURNAL CYCLE OF PRECIPITATION IS CRITICAL BUT ITS IMPORTANCE DIMINISHES AS WEEKS AND MONTHS ARE AVERAGED. ON A DAILY OR SYNOPTIC SCALE THE GENERAL CIRCULATION AND THE RELEVANT THERMODYNAMIC REGIMES ARE LIKELY THE BIGGEST CONTRIBUTORS TO REGIONAL DIFFERENCES WHILE AT LARGE DOMAIN SEASONAL SCALES SMALL BUT PERSISTENT DIFFERENCES IN THE ATMOSPHERIC FORCINGS ARE LIKELY TO BLAME FOR REGIONAL BIASES SUCH AS THOSE THAT HAVE BEEN OBSERVED BETWEEN EQUATORIAL SOUTH AMERICA AND AFRICA. TO OVERCOME THESE LIMITATIONS WE HOPE WITH THIS WORK TO BEGIN GENERALIZING VALIDATION STATISTICS THAT HAVE BEEN COLLECTED FOR INDIVIDUAL REGIONS TO APPLY TO OBSERVATIONAL AND METEOROLOGICAL REGIMES THAT ARE APPLICABLE GLOBALLY. IF WE CAN PROPERLY DEFINE THESE REGIMES SUCH THAT GPROF VALIDATION STATISTICS ARE REPRODUCIBLE ANY TIME AND ANYWHERE THAT THE REGIME IS OBSERVED THE VALIDATION PARADIGM CAN BE EXTENDED TO PREDICT VALIDATION STATISTICS GLOBALLY AS LONG AS THE DEFINED REGIMES ARE WELL OBSERVED BY SOME OF GPMS CURRENT VALIDATION NETWORKS. WE FOCUS HERE ON REGIME-DEPENDENT ERRORS ON 1 INSTANTANEOUS AND 5 SEASONAL (INDEXED BY THE CENTRAL MONTH) SCALES FOR THEIR IMMEDIATE APPLICATIONS TO IMERG IN THE CASE OF 1 DAILY PRECIPITATION AND FOR CLIMATE VARIABILITY AND TREND STUDIES IN THE CASE OF 5 SEASONAL GRIDS. WITH THIS WORK WE HOPE TO LAY THE FOUNDATION FOR PREDICTING UNCERTAINTIES AT THESE TWO SCALES IN REGIONS WITHOUT VALIDATION DATA ARGUABLY THE REGIONS IN WHICH SATELLITE UNCERTAINTIES ARE MOST CRITICALLY NEEDED. BY RELYING ON REGIMES (RATHER THAN LOCATIONS) WE HOPE TO SIGNIFICANTLY EXPAND THE APPLICABILITY OF VALIDATION DATA THAT HAS BEEN COLLECTED TO DATE THEREBY EXPANDING THE USABILITY OF THIS PRODUCT AND THE PRODUCTS WHO USE GPROF IN THE MERGED APPLICATIONS. WHILE THE APPROACH OF USING REGIMES INSTEAD OF GEOGRAPHIC LOCATIONS PERHAPS NEW TO RAINFALL VALIDATION IT IS A CONCEPT THAT HAS LONG BEEN USED TO BETTER UNDERSTAND STORM DYNAMICS AND THE BEDROCK OF MANY OF THE TRMM AND GPM FIELD EXPERIMENT PLANNING. THIS PROVIDES SOME BASIC ASSURANCES THAT THE METHOD SHOULD PROVE USEFUL FOR PREDICTING UNCERTAINTIES IN REMOTE LOCATIONS AS LONG AS THEIR PRECIPITATION REGIMES OVERLAP REGIMES THAT ARE WELL OBSERVED BY OUR CURRENT NETWORKS OF GROUND-BASED RADARS

$520,034FY2022National Aeronautics and Space AdministrationNASA

Colorado State University, Fort Collins CO

Investigators

View source on USAspending →