Airborne Passive Microwave Retrievals of Cloud Liquid Water, Total Precipitable Water, and Near‐Surface Wind Speed in the Maritime Tropics
Year: 2026
Type: article
Abstract: This paper describes improvements to geophysical retrievals from NASA's Advanced Microwave Precipitation Radiometer (AMPR) during the Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP 2 Ex). The retrieved products are validated using independent data sets, and example applications in addressing science questions about the maritime tropics are provided. Multi‐linear regression equations previously developed to retrieve cloud liquid water path (CLW), total precipitable water vapor (WV), and 10‐m wind speed (WS) from AMPR brightness temperatures in the midlatitudes were examined. Initial testing revealed that the CLW methods required modification for the maritime tropics, likely due to the stark environmental differences. Minor WS adjustments were also needed to account for the presence of a new AMPR radome. Compared with numerical simulations, the updated CLW equation performed nearly an order of magnitude better than its predecessor. Validating AMPR CLW with airborne polarimeter‐derived CLW throughout CAMP 2 Ex yielded a median absolute deviation that is less than the predecessor CLW equation's uncertainty and comparable to CLW precisions observed in past studies. In situ WV and WS validation using dropsondes was promising, with mean deviations that are less than their target uncertainties. Correlating AMPR CLW with polarimeter‐derived cloud‐top height (CTH) indicated an expected CLW ∝ CTH 2 relation for CTH < 4 km, but reduced CLW for CTH > 4 km may have been associated with cloud droplet removal via accretion and/or mixed‐phase onset. These results demonstrate the power of airborne radiometer geophysical retrievals as standalone metrics and the insight they provide when used alongside other data sets.
Source: Earth and Space Science
DOI: 10.1029/2025ea004690
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $2,650
Awards: PAST MODELING STUDIES HAVE DEMONSTRATED THAT VARIATIONS IN AEROSOL NUMBER CONCENTRATION AND TYPE CAN SIGNIFICANTLY IMPACT BOTH THE MICROPHYSICAL AND DYNAMICAL PROPERTIES OF CONVECTIVE CLOUDS. HOWEVER THE SIMULATED RESPONSES OF CONVECTIVE CLOUD CHARACTERISTICS TO AEROSOLS ARE FAR FROM CONSISTENT DUE IN PART TO THE LIMITED AVAILABILITY OF OBSERVATIONAL DATA TO INITIALIZE AND EVALUATE NUMERICAL SIMULATIONS OUR LACK OF UNDERSTANDING OF AEROSOL AND MICROPHYSICAL PROCESSES AND SHORTFALLS IN OUR MODEL PARAMETERIZATIONS. RECENT STUDIES HAVE SHOWN THAT INCREASES DECREASES OR LITTLE CHANGE TO CONVECTIVE RAINFALL CAN OCCUR IN RESPONSE TO INCREASED AEROSOL CONCENTRATIONS. ENHANCING OUR UNDERSTANDING OF AEROSOL IMPACTS ON CONVECTIVE CLOUDS AND THEREFORE THEIR REPRESENTATION IN NUMERICAL MODELS IS FURTHER COMPLICATED BY COMPLEX NON-LINEAR INTERACTIONS THAT EXIST AMONG THE MICROPHYSICAL AND DYNAMICAL PROCESSES OF CLOUDS AND THEIR ENVIRONMENT. IN ORDER TO ADVANCE OUR UNDERSTANDING OF AEROSOL PROCESSES AND THEIR MODULATION BY THE ENVIRONMENT AND HENCE BETTER PREDICT THESE PROCESSES USING NUMERICAL MODELS WE ARE IN CRITICAL NEED OF DETAILED HIGH RESOLUTION CO-LOCATED MEASUREMENTS OF AEROSOLS CLOUD MICROPHYSICS AND METEOROLOGICAL PROPERTIES. HIGHLY COMPLEX CLOUD-AEROSOL INTERACTIONS ARE OBSERVED TO OCCUR WITHIN CUMULUS AND CONGESTUS CLOUDS OVER THE MARITIME CONTINENT AND SOUTH CHINA SEA OFF THE WESTERN COAST OF THE PHILIPPINES DUE TO THE LARGE VARIETY OF AEROSOL SOURCES AND THE WIDE RANGE OF METEOROLOGICAL PHENOMENA THAT IMPACT THE REGION. THE CLOUDS AEROSOL MONSOON PROCESSES PHILIPPINES EXPERIMENT (CAMP2EX) WILL PROVIDE A ROBUST SUITE OF MEASUREMENTS WITHIN THIS IDEAL NATURAL LABORATORY THAT WILL HELP TO DISENTANGLE THE COMPLEX INTERPLAY AMONG AEROSOLS CLOUD AND THE ENVIRONMENT. THE SPECIFIC SCIENCE QUESTIONS THAT WE SEEK TO ANSWER ARE THE FOLLOWING: (1) HOW DO THE NUMBER CONCENTRATION AND TYPE OF AEROSOL PARTICLES AFFECT THE MICROPHYSICAL PROPERTIES OF SHALLOW CUMULUS AND CONGESTUS CLOUDS AND THE SUBSEQUENT DEVELOPMENT OF PRECIPITATION? (2) HOW DO THE NUMBER CONCENTRATION AND TYPE OF AEROSOLS IMPACT THE LATENT HEATING AND INVIGORATION OF CONGESTUS CLOUDS AND HENCE THEIR POTENTIAL TRANSITION TO DEEP CONVECTION AND GREATER PRECIPITATION PRODUCTION? (3) HOW DO AEROSOL NUMBER CONCENTRATION AND TYPE IMPACT COLD POOL INTENSITY AND THE SUBSEQUENT ORGANIZATION AND ENHANCEMENT OF CONVECTION? (4) IN WHAT MANNER ARE AEROSOL-CLOUD INTERACTIONS MODULATED BY ENVIRONMENTAL FACTORS AND WHICH FACTORS ARE PREDOMINANT IN REGULATING THESE INTERACTIONS? WE PROPOSE TO ADDRESS THESE SCIENCE QUESTIONS THOUGH A SYNERGISTIC APPROACH INVOLVING THE DEPLOYMENT OF DROPSONDES DURING THE CAMP2EX FIELD CAMPAIGN THE ANALYSIS OF THE DROPSONDE AND AIRCRAFT DATA COLLECTED DURING CAMP2EX AND THE SYNTHESIS OF THESE DATA INTO THE INITIALIZATION AND VALIDATION OF BOTH IDEALIZED AND CASE STUDY CLOUD-RESOLVING NUMERICAL SIMULATIONS. THESE DROPSONDE OBSERVATIONS AND NUMERICAL SIMULATIONS WILL PERMIT A DETAILED INVESTIGATION INTO THE IMPACTS OF AEROSOL NUMBER CONCENTRATION AND AEROSOL TYPE OVER A RANGE OF ENVIRONMENTAL CONDITIONS ON THE MICROPHYSICS PRECIPITATION AND DYNAMICS OF CUMULUS AND CONGESTUS CLOUDS. THE PROPOSED RESEARCH WILL ENHANCE OUR SCIENTIFIC UNDERSTANDING OF THESE COMPLEX AEROSOL-CLOUD-ENVIRONMENTAL INTERACTIONS WHICH WILL PAVE THE WAY FOR IMPROVED REPRESENTATION OF THESE PROCESSES IN NUMERICAL WEATHER PREDICTION AND CLIMATE MODELS., G7555896799
OpenAlex ID: W7134186199