Improving the accuracy of precipitation level forecast is helpful to optimize disaster warning and decision support. Based on the precipitation observation data in the time interval of 12 hours from January 2018 to January 2021 in Shandong Province and the ensemble prediction ensemble mean results of the European Centre for Medium-Range Weather Forecasting, the precipitation level forecast for 12 hours interval within 72 hours are statistically revised. Then, the effects of the original forecast of ECMWF ensemble mean precipitation forecast interpolation (EC_EPEM), the Model Output Statistics (MOS) prediction based on the EC_EPEM (EC_EPEM_MOS) and the Optimal Threat Score (OTS) prediction (EC_EPEM_OTS) are compared, and the improving effects of two statistical correction methods on precipitation level with the time interval of 12 hours prediction of the ECMWF ensemble forecast are discussed. The results indicate that the EC_EPEM_MOS has the best performance on the relatively smaller precipitation grades, while its correction effect is relatively poor for higher grades, even slightly lower than the EC_EPEM. The correction effect of the EC_EPEM_OTS is only lower than the EC_EPEM_MOS for 0.1 and 10.0 mm precipitation grades, and for the other grades it is optimal, especially for the larger grades, its correction effect is more obvious. The EC_EPEM_OTS has the best correction effect from 12 to 72 hours for both 50 mm and 100 mm precipitation grades, because the EC_EPEM_OTS increases the correction coefficient for a slightly larger grade, resulting in a low false report rate for large grades. At the same time, using a smaller correction coefficient for large precipitation also reduces the false report rate. The EC_EPEM_MOS is best in most parts of Shandong Province except for the mountains area in the middle parts for short prediction period and smaller precipitation, while the EC_EPEM_OTS is the best in the mountains area. For above medium grade, especially large precipitation, the EC_EPEM_OTS is the best in most areas of Shandong Province. The EC_EPEM_MOS correction prediction effectively reduces the problem of empty report of the EC_EPEM. The correction effect of the EC_EPEM_OTS is the best, and the rainfall area is closer to the observations in the processes of large-scale heavy rainfalls, and the overall distribution of precipitation is better grasped.

Based on daily precipitation observation data at 120 national meteorological stations in Shandong Province, monthly reanalysis data of ERA-Interim from ECMWF (European Centre for Medium-Range Weather Forecasts) and 6-hour reanalysis data from NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) from 1979 to 2018, the influence of spring atmospheric heat source intensity over the Tibetan Plateau on summer rainstorm in Shandong Province was analyzed. The results show that rainstorm days presented an increasing trend in most areas of Shandong Province from 1979 to 2018, and the increasing trend of rainstorm days was significant in southwestern Shandong and the mid-east part of northwestern Shandong. The atmospheric heat source over the Tibetan Plateau was stronger than that in other areas of East Asia in spring and summer. The intensity of spring atmospheric heat source in strong central region over the Tibetan Plateau was significantly and positively correlated with summer rainstorm index in Shandong. When the atmospheric heat source over the Tibetan Plateau strengthened in spring, the South Asia high enhanced and extended to eastward in summer, and it was easily to appear “the central pattern” at 200 hPa. At the same time, the cold vortex at 500 hPa over northeastern China was easily to generate and moved southward, and the west Pacific subtropical high over eastern Japan strengthened and moved northward, the cold and warm airflow intersected over Shandong. In additional, there was significant water vapor transporting to Shandong from south to north. The circulation configuration with low-level convergence and upper-level divergence prompted updraft enhancement over Shandong, which was beneficial to rainfall. The intensity of atmospheric heat source over the Tibetan Plateau in spring had significantly positive and negative correlation with the South Asia high intensity and the Silk Road teleconnection correlation in summer, respectively, and the circulation situation under atmospheric heat source enhancement was conducive to occurrence of heavy rainfall in Shandong.

The paper analyzed the characteristics of temperature inversion and the impact of temperature inversion on PM2.5 mass concentration in Jinan from 2008 to 2017 based on L-band radar data, temperature profiler data, micro-pulse laser radar data, PM2.5 mass concentration data and conventional meteorological observation data. The frequency of temperature inversion was 47.2%, and it showed a decreasing trend year by year, with an annual decline rate of 0.44%. In general, the frequency of temperature inversion, temperature inversion intensity and thickness were higher in winter and lower in summer, but seasonal variations of different inversion types were different. The mean thickness of ground inversion was 134 m, and the intensity of ground inversion was 2.46°C·(100 m)-1. The thickness of suspension inversion was 212 m, and the intensity of that was 1.34°C·(100 m)-1. Temperature inversion was one of the important factor affecting air quality. The occurrence of temperature inversion led to a 24.8% increase in PM2.5 mass concentration in Jinan. PM2.5 mass concentration was significantly and positively correlated with the thickness of temperature inversion, while the correlation between PM2.5 mass concentration and the intensity of temperature inversion did not pass the significance test.