Based on CLDAS grid temperature data from National Meteorological Information Center of China, SCMOC grid temperature forecast data from Central Meteorological Observatory of China and temperature observation data at weather stations of Shanxi Province, the applicability of CLDAS temperature in Shanxi Province was evaluated comprehensively by using non-independence test method. And on this basis, based on CLDAS grid temperature data, the objective correction of SCMOC temperature forecast field was studied by using the sliding training period scheme. The results are as follows: (1) The complex terrain in Shanxi Province had a certain influence on the accuracy of CLDAS temperature, and the maximum temperature of CLDAS exhibited a better accuracy than the minimum temperature of CLDAS, which indicated that the influence of terrain on deviation of the minimum temperature was more significant, and the deviation of the minimum temperature in high altitude areas was negative generally, while that in low altitude areas was positive. (2) The deviation of CLDAS grid temperature had a continuity of time in space. After the simple deviation correction, the accuracy of the maximum and minimum temperature of CLDAS promoted by 1.1% and 9.7%, respectively, the revised temperatures were more consistent with observation. (3) Based on improved CLDAS grid temperature, the accuracy rate of SCMOC temperature forecast improved significantly by using the sliding deviation correction scheme. Compared to SCMOC, the accuracy rate of the 24-hour maximum and minimum temperature forecast in Shanxi Province in 2019 respectively increased by 2.7% and 4.7% after the sliding deviation correction. The quality of short-term temperature forecast after the sliding deviation correction had greatly improved, and it was superior to the subjective forecast of forecasters.

Based on the model sounding analysis field and forecast field of North China RMAPS (rapid-refresh multi-scale analysis and prediction system), the environmental parameter characteristics of four types of severe convection weathers were contrastively analyzed in Shanxi Province, and the classification indexes and criterion of severe convection weathers were summarized. And on this basis, the category forecasting scheme of severe convection weathers was designed in Shanxi Province, then the occurrence probability of severe convection weathers with four types on grid points was calculated, and the feasibility of classification forecast of severe convection weathers was further explored. The results are as follows: (1) The environmental parameters including convective available potential energy (CAPE), K index, temperature difference between the middle and lower level, temperature dew point deficit on low level, 600 hPa temperature and low-level vertical wind shear had a certain indicative significance for distinguishing types of severe convection weathers in Shanxi. (2) The low-level vertical wind shear and 600 hPa temperature between hail or thunderstorm-gale and short-term heavy precipitation or thunderstorm had significant difference. Using the 20.0 ℃ temperature difference between 700 hPa and 500 hPa as a threshold, the thunderstorm-gale could be distinguished from short-term heavy precipitation, hail and thunderstorm weathers. Taking the 4.0 ℃ temperature-dew point deficit on 700 hPa as a threshold, the short-term heavy precipitation could be distinguished from hail, thunderstorm-gale and thunderstorm weathers. The above results could be used as the basic criteria of recognition of severe convection in Shanxi Province. (3) The classification forecasting scheme had a certain forecasting ability to severe convections in Shanxi Province, and it could capture the possible falling areas of hail, thunderstorm-gale and short-term heavy precipitation to some extent during a large-range severe convection process. The short-term forecasting ability of classification scheme was slightly higher than that of average level of forecasters’ subjective forecast, and the threat score was improved by about 0.01-0.06.

Based on the monthly precipitation observation data at 21 weather stations in North China, global reanalysis data from NCEP/NCAR and circulation indexes data from National Climate Center of China from 1955 to 2014, the variation tendency, mutation and periodic characteristics of cyclonic wind shear frequency in low level in North China were analyzed by using the trend analysis, Mann-Kendall test and wavelet analysis methods, and the influence factors of cyclonic wind shear were preliminary discussed. Results show that the frequency of low-level cyclonic wind shear in North China decreased significantly during 1955-2014, the mutation of cyclonic wind shear frequency appeared in 1967, and there was quasi-3-year period oscillation during 1955-1965 and 1992-2000, while the 4-year period oscillation was significant during 1980-1992. The mutation and periods characteristics of low level cyclonic wind shear frequency were basically coincide with the precipitation in the same periods in North China. The turning change of low-level cyclonic wind shear was obvious in North China, which was mainly caused by the more significant adjustment of atmospheric circulation in the previous year.