A study on the precipitation structure of a northward-moving extratropical cyclone based on GPM satellite observations

Based on observational data from the Global Precipitation Measurement (GPM) satellite,this study investigates the macro-and micro-physical characteristics of precipitation associated with a northward-moving extratropical cyclone.The horizontal distribution and the fine-scale vertical structural characteristics of relevant physical quantities are analyzed on sectoral partitioning and precipitation-type classification within the cyclone.This approach elucidates the key macro- and micro-physical processes and their coupling mechanisms governing precipitation formation in the extratropical cyclone.Results indicate that precipitation associated with northward-moving extratropical cyclone is primarily stratiform.The southern sector exhibits typical warm-sector precipitation characteristics,with deeper convection,higher cloud tops,greater precipitation intensity,and more active convective processes.In contrast,the northern rainband is characterized by relatively shallow precipitation systems,dominated by shallow convective and stratiform types.Regarding raindrop size distribution,both convective and shallow convective precipitation exhibit higher particle number concentrations than stratiform precipitation.The effective particle radius in convective precipitation is larger than in stratiform precipitation,whereas in shallow convective precipitation it is smaller.Overall,effective particle radius increases with cloud-top height,while no significant correlation is observed with particle number concentration.In the southeastern quadrant of the cyclone,coalescence processes dominate in over 60% of precipitation samples,followed by breakup processes (exceeding 20%),with evaporation having the least influence.In contrast,within the northwestern quadrant of the cyclone,precipitation type governs the microphysical processes:stratiform precipitation is predominantly influenced by breakup processes (55.15%),while shallow convective precipitation is primarily dominated by coalescence processes (accounting for as high as 89%).This study not only enhances the scientific understanding of macro- and micro-scale characteristics and evolutionary mechanisms of extratropical cyclones in middle and high latitude regions,but also provides a theoretical foundation for improving cloud microphysical and cumulus convection parameterization schemes in numerical weather prediction models for middle and high latitude cyclones.