Evaluation and error analysis of the “21.7” heavy rain in Henan simulated by CMA-MESO model
In order to analysis the simulated performance of CMA-MESO model for heavy rain occurred in Henan from 19 to 20 July 2021, not only the conventional observation, but also the unconventional observation as for radar and satellite used traditional and new spatial verified method that could reveal the deviation characteristics of convective storms and mesoscale convective systems (MCS, in satellite infrared channel) simulated by model, and then focus on the source of model deviation from the perspectives of water vapor, momentum, trigger and maintenance mechanism of precipitation. The results showed that: (1) the model could well capture the shape of the rain band, the duration of weak echoes and the evolution trend of intensity and area of MCS before main precipitation. (2)The model deviation appeared on that it underestimated the intensity of precipitation and failed to predict the extreme hourly precipitation at Zhengzhou station, also it misreported the evolution of hourly precipitation of main band and seriously underestimated the duration of convective storms and severe convective storms, as well as it missed the sharp increase of MCS area in the afternoon and the simulated location deviation of MCS was west and south.(3) The origin of model deviation was mainly owing to the simulation of water vapor, as for the vertical distribution of simulated water vapor was not appropriate, and the simulated water vapor transportation from Typhoon In-Fa and Typhoon Cempaka were both weak. In fact, the weak low-level jet and insufficient ultra low-level easterly jet pulsation mainly caused the insufficient of simulated water vapor transportation. Moreover, the failure to forecast the stably maintained convergence line at surface near zhengzhou station, combined with the deficiency of atmospheric instability and underestimation of unstable energy, making the convection not seriously developed and resulting in underestimated of precipitation.