The vertical evolution of the cloud effective radius (Re) reflects the precipitation-forming process. Based on observations from the first Chinese next-generation geostationary meteorological satellites (FY-4A, Feng Yun 4), we established a new method for objectively obtaining the vertical temperature vs. Re profile. First of all, Re was calculated using a bispectral lookup table. Then, cloud clusters were objectively identified using the maximum temperature gradient method. Finally, the Re profile in a certain cloud was then obtained by combining these two sets of data. Compared with the conventional method used to obtain the Re profile from the subjective division of a region, objective cloud-cluster identification establishes a unified standard, increases the credibility of the Re profile, and facilitates the comparison of different Re profiles. To investigate its performance, we selected a heavy precipitation event from the Integrative Monsoon Frontal Rainfall Experiment in summer 2018. The results showed that the method successfully identified and tracked the cloud cluster. The Re profile showed completely different morphologies in different life stages of the cloud cluster, which is important in the characterization of the formation of precipitation and the temporal evolution of microphysical processes.
6 August 2020 in Journal of Geophysical Research: Atmospheres
From 29 June to 6 July 2016, China's Yangtze River Basin experienced heavy precipitation, causing more than 200 deaths and affecting tens of millions of people. Using ERA5 reanalysis, soundings, and satellite observations from FY‐2 and Global Precipitation Measurement (GPM), we reviewed this heavy rainfall event from the perspective of its meteorological triggers and the cloud microphysics. As the cloud system moved eastward from the Tibetan Plateau, precipitation particles got larger and denser, and the enhancement of stratiform precipitation contributed the most precipitation. The riming and aggregation processes, the dominant growth modes of particles, were significantly enhanced between 5.5 and 7 km. The increase in the echo‐top height had a considerable positive effect on the near‐surface particle size (from ~1.0 mm at 4 km to ~1.5 mm at 10 km), but this feature was not significant over the Tibetan Plateau. We suggest that the microphysics of this event was dominated by the combination of the eastward moving cloud system, which acted as continuous “seeder” cloud, and the increase in water vapor associated with the low‐level vortex and jet, which generated enhancing “feeder” cloud. The particles from the “seeder” cloud grew by the lower “feeder” cloud, thus increasing the particle size to enhance the precipitation. Overall, the generation and movement of such a cloud system is an important atmospheric disturbance for the generation of heavy precipitation downstream, and could be an early warning signal in the forecasting of heavy rainfall in China during the Meiyu period.
1 November 2023 in Food Science and Human Wellness