X-band dual-polarization radar-based hydrometeor classification for Brazilian tropical precipitation systems

Author(s)

Ribaud, Jean-Francois ^[1] ; Toledo Machado, Luiz Augusto ^[1] ; Biscaro, Thiago ^[1]

Affiliation

^[1] Ctr Weather Forecast & Climate Studies CPTEC, Natl Inst Space Res INPE, Rodovia Presidente Dutra, Km 40, BR-12630000 Cachoeira Paulista, SP - Brazil

• Document type: Journal article
• Source: Atmospheric Measurement Techniques; v. 12, n. 2, p. 811-837, FEB 6 2019.
• Web of Science Citations: 1

Abstract

The dominant hydrometeor types associated with Brazilian tropical precipitation systems are identified via research X-band dual-polarization radar deployed in the vicinity of the Manaus region (Amazonas) during both the GoAmazon2014/5 and ACRIDICON-CHUVA field experiments. The present study is based on an agglomerative hierarchical clustering (AHC) approach that makes use of dual polarimetric radar observables (reflectivity at horizontal polarization Z(H), differential reflectivity Z(DR), specific differential-phase K-DP, and correlation coefficient rho HV) and temperature data inferred from sounding balloons. The sensitivity of the agglomerative clustering scheme for measuring the intercluster dissimilarities (linkage criterion) is evaluated through the wet-season dataset. Both the weighted and Ward linkages exhibit better abilities to retrieve cloud microphysical species, whereas clustering outputs associated with the centroid linkage are poorly defined. The AHC method is then applied to investigate the microphysical structure of both the wet and dry seasons. The stratiform regions are composed of five hydrometeor classes: drizzle, rain, wet snow, aggregates, and ice crystals, whereas convective echoes are generally associated with light rain, moderate rain, heavy rain, graupel, aggregates, and ice crystals. The main discrepancy between the wet and dry seasons is the presence of both low-and high-density graupel within convective regions, whereas the rainy period exhibits only one type of graupel. Finally, aggregate and ice crystal hydrometeors in the tropics are found to exhibit higher polarimetric values compared to those at midlatitudes. (AU)

• FAPESP's process: 16/16932-8 - Hydrometeor classification using dual-polarization radar data to improve numerical prediction and data assimilation
• Grantee: Jean-François Ribaud
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/14497-0 - Nowcasting of intense thunderstorms and understanding of the physical processes inside clouds: the SOS-CHUVA (Severe Weather Observation System)
• Grantee: Luiz Augusto Toledo Machado
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants