Large‐scale dynamic, heat and moisture structures of monsoon‐influenced precipitation in the East Asian monsoon rainy area. (8th January 2021) - Zhang, Chunyan
Abstract: This study investigated large‐scale dynamic structures along with heat and moisture budgets associated with monsoon‐influenced precipitation over a typical rainy domain in the East Asian monsoon region. Large‐scale dynamically and thermodynamically consistent forcing data based on multiple measurements were produced by a one‐dimensional constrained variational analysis method. Using the forcing data, distinct characteristics of large‐scale states were documented for cases of notable pre‐monsoon rainfall before the South China Sea monsoon onset (SCSMO), extreme rainfall during SCSMO, and persistent strong rainfall after SCSMO. The pre‐monsoon period mainly resulted from weak and discrete cloud regimes. The extreme‐rain period was associated with a severe deep convective system moving from the west, and the persistent‐rain period was related to moderate convective cells separated from the strong convective system over the northern South China Sea. Large‐scale features including vertical velocity, wind convergence, and diabatic heating and drying were the strongest (weakest) during the extreme‐rain (pre‐monsoon) period. For the pre‐monsoon and persistent‐rain periods, the period‐averaged profiles of vertical velocity and diabatic heating and drying showed a one‐peak structure. However, during the extreme‐rain period, a leap‐forward mutation was seen in the vertical structure and magnitude of these large‐scale states. The multiple peaks shown in the vertical profiles of vertical velocity and diabatic heating during the extreme‐rain period may indicate various convective cloud systems co‐existed. The diabatic heating profiles of extreme rainfall indicated that the first rainfall peak was related to the successive occurrence of stratiform anvils and convective clouds, while the second rainfall peak, which was most intense, was associated with shallow convective clouds, severe deep convective clouds, and detraining stratiform anvils. Abstract : Time‐pressure cross‐section of apparent heat source Q1 (K‐day‐1) during extreme‐rain period. The black line represents the surface rainfall rate. Cloud regimes were different for rainfall cases before, during, and after the South China Sea monsoon onset. Rapid enhancements existed in the diabatic heating and drying structure and magnitude between two rainfall peak processes during a sudden extreme rainfall event. Large‐scale dynamic structures as well as heating and drying profiles showed a one‐peak structure during the pre‐monsoon and persistent‐rain periods, while a multi‐peak structure was observed during the extreme‐rain period.