The purpose of this study was to improve utilization rate of climate resources and reasonably optimize layout of winter facility agriculture in Henan Province. Based on daily minimum temperature data from 113 national meteorological stations during 1981-2018 in Henan Province, the mathematical statistics method was used to calculate standard deviation of minimum temperature in winter and climatic probability, frequency and occurrence intensity of different low temperature disaster indices. The low temperature risk index of facility agriculture was constructed by using the equal weight method. The low temperature risk levels of facility agriculture were classified using the optimal clustering method of ordered samples combined with low temperature disaster data, and the risk assessment was conducted using the risk level combined with land-cover data. The results show that the climatic probability and occurrence frequency of low temperature disaster (less than or equal to -5 ℃ ) in all parts of Henan Province are more than 0.80, so it is not suitable for development of small plastic arch sheds, and it is not suitable to use single-layer plastic greenhouses for facility agricultural production. The climatic probability and occurrence frequency of temperature less than or equal to -10 ℃ in both Xinyang and southern Nanyang are less than 0.20, it is suitable for development of plastic greenhouses. The climatic probability and occurrence frequency of temperature less than or equal to -10 ℃ in Hebi, Anyang and Puyang are all more than 0.80, so in these regions solar greenhouses should be developed to ensure crop growth in facilities. In the plastic greenhouse development area, Gushi County and Shangcheng County of Xinyang are mild risk areas for low temperature disasters, most of Xinyang, parts of Nanyang and Zhoukou are moderate risk areas, and all other areas are severe risk areas. In the solar greenhouse development areas, Puyang, Anyang and parts of Hebi are areas with high risk of low temperature disasters. Therefore, the low temperature disaster risk of different levels in Henan Province in winter has a certain regional pattern. Arrangements on planning of facility agriculture should be done in different regions according to local low temperature disaster risks.

Based on the merged data of CloudSat from June to August during 2007-2010, the occurrence probability, vertical structure, type, microphysical structure of single-layer and multi-layer clouds and their environmental temperature and humidity over Liaoning Province were investigated. The results are as follows: (1) The clouds were mainly composed of single-layer cloud over Liaoning Province in summer from 2007 to 2010, and then followed by double-layer cloud. The single-layer clouds were mainly consisted of cirrus and altostratus, and then followed by altocumulus and deep convection. The cirrus mainly distributed at upper layer of multi-layer clouds. The altocumulus, altostratus and stratocumulus mainly distributed at lower layer of double-layer clouds, while the altostratus and altocumulus mainly dominated at middle layer and the stratocumulus mainly dominated at lower layer of triple-layer clouds. (2) The echo intensity and cloud thickness for each layer of multi-layer clouds were less than those of single-layer cloud. (3) The vertical profiles of microphysical quantities (particle number density, effective radius and cloud water content) for each layer of multi-level clouds were similar to single-layer cloud, while their average values were relatively smaller, and they decreased gradually from top to bottom, which were related to cloud types, namely the values of deep convection were the largest and cirrus were the smallest. (4) Compared with clear sky, the specific humidity on cloudy weather was larger, which indicated that the water vapour of atmosphere on cloudy weather was more abundant. The average near-surface temperature was lower under the cloudy weather during the daytime, while it was opposite at night.

Based on conventional ground observation data of weather stations and pollutant mass concentration observation data from environment monitoring stations in Liaoning Province, ECMWF reanalysis data with 0.5°×0.5° spatial resolution, a heavy pollution process caused by straw burning from 7 to 10 November 2015 in Liaoning Province, the differences and its causes of pollution among different cities were analyzed. The results are as follows: (1) CO was main pollutant during the heavy pollution process. The mass concentration of PM2.5 appeared two peak stages, and it was well corresponded to CO and NO2 mass concentrations. The visibility was mainly affected by PM2.5 concentration and relative humidity. (2) The effect of previous weak precipitation more than 1.0 mm on wet deposition of pollutants was obvious in Yingkou and Panjin, while the precipitation in other cities was smaller, and the high humidity environment was conducive to moisture absorption and growth of pollutants. (3) The horizontal wind speed from ground to 700 hPa during the heavy pollution was close to 4 m·s-1, the atmospheric stratification was stable, and the temperature inversion was obvious, which was beneficial to inhibit the vertical diffusion of pollutants. (4) The warm layer around 0 ℃ between 850 hPa and 900 hPa over cities except for Jinzhou maintained for a long time, which might provide favorable environment for the melting, collision and growing of pollutant particles. (5) There were many fire points in Jilin and Heilongjiang Province during the pollution process. Therefore, the main sources of pollution in central Liaoning Province came from the wide straw burning upwind, so it was necessary to strengthen the control of local and external pollution sources under the favorable weather conditions to the pollutants accumulation.

By using the data of the visibility observations and NCEP reanalysis data during 2002 － 2011，the processes of low visibility weather in North China has been studied．The results show that the circulation situation on 500 hPa that caused low visibility weather in studied area could be divided into three types including two troughs and a ridge type，low trough type and zonal flow type，and the automatic identification system could be established to recognize the three weather types and eliminate other situations from these three types． On this basis，the use of K － index，the dew point temperature difference and pseudo－equivalent potential temperature difference between 500 hPa and 850 hPa gave a further physical diagnosis，and at last the forecast of low visibility weather could be obtained． The low visibility weathers occurring in North China in 2012 were forecasted by using the method mentioned above，the results show that the prediction effect of this forecast method was fine．