The accuracy evaluation of satellite-derived cloud cover is foundation of operational applications, and it is of great significance for effectively leveraging the high spatiotemporal resolution advantages of satellite remote sensing and compensating for the scarcity of ground-based observations. This study focuses on the Ningxia region, a typical arid and semiarid region, and utilizes ground observations of total cloud cover amount at five time points (08:00, 11:00, 14:00, 17:00, and 20:00, Beijing time, the same below) in 2019 to validate and evaluate the Fengyun-4A ( referred to as “FY-4A”) satellite cloud cover fraction product, then uses the normalized mixed correction method to correct the monthly cloud cover fraction products and analyze the daytime spatiotemporal distribution characteristics of cloud cover fraction in Ningxia. The results indicate that: 1) The monthly and daily variation trends of the FY-4A cloud cover fraction product in Ningxia region are highly consistent with those of ground manual observations of total cloud amount. The correlation coefficients between FY-4A satellite-derived cloud cover fraction and ground observed total cloud amount range from 0.7 to 0.9 across the whole region and at individual meteorological stations, but the derived cloud cover fractions are generally lower than the observed total cloud amounts. 2) In terms of the consistency rate between the total cloud amount and cloud cover fraction at five different times of a day, the consistency rates at 11:00, 14:00, and 17:00 are higher than those at 08:00 and 20:00. For cloud cover categories test, the consistency rates are in the order of clear sky > overcast > partly cloudy > mostly cloudy. 3) The normalized mixed correction method effectively reduces the bias between the FY-4A cloud cover fraction product and the manual total cloud amount observations. After correction, the monthly average values of the cloud cover fraction product are in good agreement with the cloud amounts observed at meteorological stations. 4) The annual average daytime cloud coverage in Ningxia ranges from 30% to 70%. Higher cloud cover fractions are found along the Helan Mountains, in the Yellow River irrigation area (from Shapotou District, Zhongwei, to Yinchuan), and in Haiyuan County and Guyuan City. The lowest cloud cover occurs in the eastern parts of Huinong District, Dawukou District, and Pingluo County in Shizuishan City. Cloud cover fraction is generally higher in May and June, and lowest in December.

Heavy rainfalls and floods, waterlogging triggered by rainstorms are one of the most serious natural disasters in Ningxia. This paper constructs an integrated rainstorm hazard risk warning model in Ningxia to effectively predict the risk of heavy rainfall and issue risk warnings in advance, by using the Analytic Hierarchy Process (AHP) and Delphi method, and considering four factors including hazard, exposure, vulnerability, and disaster mitigation capacity, the model incorporates 14 evaluation indicators such as population, economy, elevation, and vegetation etc. in Ningxia. Combined with GIS technology, a rainstorm event simulation was conducted. The results show that the model comprehensively and objectively reflected integrated risk distribution during rainstorms. The analysis of the rainstorm on July 10, 2022 indicated that the regions with the highest hazard were Jinfeng District and Xixia District of Yinchuan, Litong District of Wuzhong, Qingtongxia County, eastern Yanchi County, and Yuanzhou District of Guyuan; the highest exposure was in Yinchuan; the highest vulnerability was in western Qingtongxia, Tongxin County, Haiyuan County, Xiji County, and Pengyang County; the weakest disaster mitigation capacity was in Haiyuan County, and the highest integrated risk areas were Jinfeng District of Yinchuan, Litong District of Wuzhong, Haiyuan and Xiji County. Integrating the model with smart grid forecasting, the integrated rainstorm hazard risk can be calculated, which provides scientific basis for precise prevention in practical operations.