The CMA land data assimilation system (CLDAS) provides high spatio-temporal resolution datasets, which offers valuable data support for the fine meteorological services, while the applicability assessment of data is an important basis for its application. Based on CN05.1 gridded observation data from the National Meteorological Information Center and observation data at 119 national meteorological stations in Inner Mongolia, the applicability of 2 m mean temperature and precipitation products of CLDAS in Inner Mongolia was examined and evaluated, and was compared with ERA5 from the European Centre for Medium-range Weather Forecasts (ECMWF) and the CRU TS (Climatic Research Unit gridded Time Series) reanalysis data from the UK. The results indicate that three datasets can effectively reflect the spatial distribution characteristics of annual precipitation and annual mean temperature in Inner Mongolia, but they underestimate annual precipitation and overestimate annual mean temperature in most areas, and CLDAS datasets can also describe the influence of terrain change on temperature and precipitation. The spatial distributions of precipitation variability from CLDAS and CRU TS data are better than that from ERA5 data in Inner Mongolia. The linear trends of CRU TS and ERA5 temperature data are similar to CN05.1 observation data, but the warming rates are higher than observations, while the CLDAS temperature product shows the cooling trend in local areas of Inner Mongolia. Whether monthly or seasonal scale, the correlation coefficients between CLDAS precipitation, mean temperature and observation values at 119 stations in Inner Mongolia are higher than those of CRU TS and ERA5 data, and their average absolute errors are smaller than those of CRU TS and ERA5 data. Compared with the station observation data, the largest errors of CLDAS temperature and precipitation products appear in the Hetao region of Inner Mongolia.

Based on the WRF model, a hail process was analyzed and simulated in central Inner Mongolia on 29 July 2015. The influence of cumulus and microphysics parameterization schemes on hail simulation was discussed preliminarily. The temporal changes of the mass concentration of liquid and solid precipitation particles were affected by microphysics and cumulus parameterization schemes, and water vapor and energy and dynamic conditions were mainly affected by cumulus parameterization scheme. Considering the threat score (TS) of different grades precipitation and the simulation effect of the two convective processes in Hohhot, KF scheme was better, followed by G3 and GD, and BMJ was worse in four kinds of cumulus parameterization schemes. Meanwhile Lin and WSM6 schemes were better in five kinds of microphysics parameterization schemes. WSM6-KF scheme had advantages in simulation of temporal changes of precipitation particles, water vapor and energy and dynamic conditions.

Based on  daily rainfall  from 34 national  meteorological observation stations in the Hetao area , Inner Mongolia during 1961-2018, extreme precipitation events and extreme precipitation processes were analyzed in the past 58 years. Atmospheric circulation features of typical extreme precipitation processes were aslo analyzed. The main results are as follows: (1) Average annual precipitation decreased from southeast to  northwest, and precipitation was rich from July to August. The precipitation decreased significantly in August and increased significantly in May, June and December. (2) The thresholds of extreme precipitation became lower from southeast to  northwest, the historical maximum extremum occurred in Wushenzhao  of Ordos,  the historical minimum extremum occurred in Hailisu of Bayannur. The frequency of extreme precipitation events was more than five times in most areas, the intensity became weaker from southeast to northwest. (3) The extreme precipitation events was most from July to August, and its intensity was strongest in August. The frequency of extreme precipitation events and the intensity increased significantly in September. (4) The annual average extreme precipitation process intensity decreased significantly, the process precipitation was concentrated in Tumote Zuo Banner, Ejin Horo Banner and the city of Huhhot. (5) The extreme precipitation processes were influenced by the southwest flow at the front of trough, and the plentiful vapor and exceptionally strong updraft flow could easily cause extreme precipitation events.