Abstract:

Planetary boundary layer (PBL) parameterization has significant impacts on the simulation and prediction of climate, weather, and environmental air quality. Here, ideal experiments were conducted using the single-column model to study the response characteristics of specific humidity and potential temperatures on soil moisture under different PBL parameterizations. A heavy precipitation synoptic process in Xinjiang from 15th-18th August 2019 was simulated and verified with six PBL parameterizations, including YSU, ACM2, BOULAC, GBM, MYJ, and QNSE. As the soil moisture increases, the simulated atmospheric boundary layer presents significant characteristics, namely, increasing specific humidity, decreasing potential temperatures, and decreasing boundary layer height. In GBM and ACM2 cases, the vertical water vapor transport efficiency was low, atmospheric specific humidity was also low, the potential temperature was high, eddy action scope was large, and precipitation was underestimated. In QNSE and MYJ cases, the vertical water vapor transport efficiency was high, atmospheric specific humidity was high, the potential temperature was low, eddy action scope was small, and precipitation was overestimated. The maximum 2 m specific humidity was achieved using QNSE and MYJ, while the minimum 2 m specific humidity was by ACM2. The lowest 2 m temperature was achieved at nighttime using QNSE, while the highest 2 m temperature was at daytime using MYJ. The highest 10 m wind speed was achieved using QNSE and MYJ. These simulating characters are closely related to the differences in the vertical water vapor transport efficiency of the different PBL parameterizations.

Key words: weather research and forecasting model, single column model, planetary boundary layer parameterization, soil moisture