一次闽南暖区暴雨的多尺度动力过程.

As a key problem in meteorological research, the dynamical processes of warm-sector rainstorms have been of continuing interest to scholars. Using the functional analysis apparatus of multiscale window transform (MWT), and the MWT-based localized energetics analysis and theory of canonical transfer, we have analyzed the warm-sector torrential rain on May 7, 2018 in southern Fujian Province for an understanding of its underlying dynamical processes. First, the atmospheric fields from the ERA5 data are reconstructed onto three scale windows, namely, the background window, the synoptic scale window, and the rainstorm window. From the reconstructed fields the upper-layer and lower-layer jets are well represented on the background window, and the vertical motion is clearly seen on the rainstorm window. Previously it has been believed that the warm-sector rainstorms are characterized by weak baroclinicity, but here baroclinic instability matters as well as barotropic instability. It is found that the dynamical processes differ with height. In the lower layer, barotropic instability dominates, and the barotropic canonical transfer directs to the rainstorm window from both the background and synoptic scale windows. In the middle layer, the instability is mixed; apart from barotropic instability, the baroclinic canonical transfer also brings available potential energy from the background window to the rainstorm window, which is then converted into kinetic energy, maintaining the rainstorm-scale motion in the middle layer. The same as the lower layer, the upper layer sees only the canonical energy transfer from the background window to the rainstorm window. [ABSTRACT FROM AUTHOR]