| 摘要 |
Based on conventional meteorological observation data, radar data, satellite cloud images, microwave radiometers and other data, a rainstorm to heavy rainstorm process in Fuxin from August 19 to 21, 2024 was analyzed from aspects of precipitation conditions, circulation patterns, water vapor conditions, dynamic characteristics, and evolution of small-scale systems. The results show that during this precipitation process, the subtropical high was northward and stable. The low vortex moved eastward and northward along the edge of the subtropical high. The blocking high and the cut-off low vortex system were deep, and a short-wave trough formed in the middle latitudes. Cold air moved eastward to continuously converge with warm and humid air currents from the northwest side of the subtropical high over Fuxin. The low-level jet stream guided the moisture from the periphery of the subtropical high to be transported to Liaoning, and a water vapor convergence center formed in Fuxin. The upward movement was intense, which was conducive to the occurrence of heavy precipitation. As the system continued to develop, the low-level water vapor convergence center gradually extended to the upper and middle levels, providing the necessary water vapor conditions for the rainstorm. The strengthening and maintenance of positive vorticity in the middle and lower levels were the result of the coupling effect between the low vortex and the low-level jet stream. The mesoscale and small-scale convective systems all had the characteristic of backward propagation. In the early stage of the convection, the updraft movement was strong. On the infrared cloud image, TBB decreased significantly, and the cloud top height rose obviously. As the convective system developed, the newly formed convective cells merged with the mature cells, so that rainstorm cloud clusters continuously developed. The strong echo center was low, and the precipitation efficiency was high. Under the effect of the train effect, a continuous rainstorm process occurred in Fuxin. With the increase of atmospheric water vapor and liquid water content, short-term heavy precipitation appeared. At the same time, the changing trend of water vapor derived by microwave radiometer inversion was relatively consistent with that of precipitation. The continuous transportation of water vapor was a necessary condition for the occurrence of the rainstorm. |
