| As the main component of the water cycle,clouds are closely related to the occurrence,development,and extinction of precipitation.Cloud top height is of great significance as a cloud parameter.With the rapid development of remote sensing technology,selecting remote sensing data to retrieve precipitation cloud top height has become an important method,and faster and better retrieval of cloud top height has important practical significance.Based on the single channel brightness temperature method,this thesis selects the data from the Sunflower 8 satellite(H-8)to retrieve cloud top height and introduces a water vapor channel for correction.A single-channel brightness temperature method combined with a water vapor channel is proposed to retrieve cloud top height.Considering the impact of H-8 scanning angle and cloud top temperature in different seasons,the retrieval area is divided,and the cloud top height difference and 10.3 μm radiant brightness temperature are statistically analyzed.Based on the analysis results,the precipitation cloud brightness temperature screening threshold is revised.Finally,the impact of a convective precipitation cloud cluster in Hunan on the traffic capacity of Changsha-controlled airspace is analyzed.The work of this article is as follows:(1)Statistical analysis was conducted on precipitation cloud top height data detected by GPM satellite DPR from 2019 to 2021,including four aspects of precipitation type cloud top height variation,monthly variation,seasonal variation,and annual variation.The precipitation is mainly layered precipitation,with the least convective precipitation but the highest cloud top height of convective precipitation.There is no significant difference in annual changes.Both monthly and seasonal changes show a trend of rising first and then falling.The seasonal changes show a trend of high in summer and low in winter,consistent with monthly changes.The spatiotemporal distribution characteristics of precipitation cloud top height data have a good consistency.(2)Select a 10.3 mm brightness temperature to retrieve the cloud top height and comprehensively compare the mean,correlation,deviation,and fit of H-8 cloud top height and precipitation cloud top height with different precipitation types.The average difference between the two is 1.5 km,and the cloud top height of H-8 is relatively high,with a general correlation.The root means square error of the two is 2.4,the average absolute error is 1.9,and the standard deviation is 1.7.There is a significant deviation.(3)Introducing a water vapor channel to correct the cloud top height of H-8,a single channel brightness temperature method combined with the water vapor channel to retrieve cloud top height is proposed.Compared to the previous revision,the cloud top height of H-8significantly decreased,with a difference of 0.1 km from the cloud top height of precipitation clouds,a correlation coefficient of 0.7,and an average absolute error of 0.8,indicating a significant decrease in the deviation.At the same time,comparing the H-8 cloud top height with the official H-8 cloud top height retrieval product,the correlation coefficient is 0.93,the root mean square coefficient is 0.54,the average absolute error is 0.43,and the standard deviation is 0.54,verifying the feasibility of the proposed method.(4)Considering the impact of H-8 scanning angle and brightness temperature differences in different seasons,the regional division was conducted,and statistical analysis was conducted on cloud top height differences and 10.3 mm radiation brightness temperature.The cloud top height differences increased with the increase of latitude,and there were significant differences in radiation brightness temperature in different seasons.Finally,based on the statistical results,the infrared radiation brightness temperature screening threshold for precipitation clouds was revised.Improve the method of retrieving cloud top height using a single channel brightness temperature method combined with a water vapor channel.(5)The single-channel brightness temperature method combined with the water vapor channel inversion of cloud top height method is applied to Changsha airspace and air routes.Convective precipitation is selected to provide reference opinions for the safe operation of civil aviation from horizontal and vertical directions.The practicality of this method is discussed,and a capacity evaluation model is selected to analyze the impact of this precipitation on the actual operation of Changsha airspace and air routes. |
