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This study assesses the midsummer precipitation prediction over eastern China by the dynamic downscaling method. Based on the Climate Forecast System version 2 of the National Centers for Environmental Prediction and the Weather Research and Forecasting Model, the prediction performance of global and regional models on the July precipitation over eastern China is further analyzed by hindcast experiments from 1982 to 2010 and prediction experiments from 2011 to 2021. The results suggest that the regional model forced by the global model can noticeably improve the prediction skill for precipitation in eastern China, especially in the region from the South of North China to the Yangtze River Basin, referred as the northern China in this paper. In addition, we perform a diagnostic analysis of the reason for the improvement of the model prediction skill. The results indicate that the high resolution of the regional model and the refinement of physical process parameterizations contribute to improving the simulation ability for the East Asian atmospheric circulation pattern, heat flux, especially for the meridional teleconnection pattern in East Asia and the sensible heat flux in the northern China, thus further improving precipitation prediction. [ABSTRACT FROM AUTHOR]

The data of lightning flash count, rainfall, radar reflectivity, vertical wind shear (WS), surface dew point temperature (DP) and particulate matter up to 10 μm in size (PM10) over Guilin, China from July 2010 to December 2019 were studied to check whether aerosol invigoration effect (AIV) exists in the study area. It was found that convective rainfall fluctuates less when compared with lightning in convective system. A hypothesis was put forward that the difference in fluctuations between convective rainfall and lightning is attributed to AIV. To test this hypothesis, lightning yield, which is defined as the ratio between lightning and rainfall, was analyzed. It was found that lightning yield has a positive correlation with PM10 when WS is low and DP is high for convective precipitation. It was also found that for the weak WS cases, when aerosol conditions are shifted from super pristine to the optimal concentration (Nop), lightning yield increases with increasing PM10; whereas for concentrations greater than Nop, lightning yield decreases with increasing PM10. Nop would be larger for higher DP. The results are in line with the previous studies showing that AIV depends strongly on weak wind shear and/or warm cloud base. This suggests that AIV exists in the study area, and suggests that the hypothesis is reasonable, and lightning yield can be used as a surrogate to study AIV. [ABSTRACT FROM AUTHOR]

Using the NCEP/NCAR reanalysis and station observations in China during 1979–2018, features of propagation of baroclinic wave packets in the upper troposphere and their relationships with precipitation over the middle and lower reaches of the Yangtze River (MLRYR) in daily climatology are investigated after having components with periods longer than 9 days filtered out. It is demonstrated that in the filtered daily climatology, the baroclinic wave packets still exist. The wave packet migrates eastward on the northern sides of the westerly jet stream axis whereas it does not move explicitly in the southern side of the axis in the upper troposphere. The filtered daily precipitation over MLRYR is mainly affected by the wave packets in the region south of the westerly jet axis. These results are very meaningful for better understanding behaviors of Rossby waves in daily climatology and the causes of daily precipitation variations in MLRYR. [ABSTRACT FROM AUTHOR]