Research On Cloud Base Height Retrieval And Application Based On FY-4A

The cloud plays a vital role in the radiation balance and water cycle of the earthatmosphere system.Carrying out cloud parameter research has a very positive significance for the protection of meteorological elements,weather modification,and military operations.The paper uses the Advanced Geosynchronous Radiation Imager(AGRI)installed by the latest generation of geostationary orbit meteorological satellite FY-4A in China to study the retrieval and application of cloud base height,and evaluates the cloud top height product of FY-4A,which has certain reference significance for making full use of and developing the cloud parameter products of the FY-4A.The paper mainly carried out the following work:(1)Summarized the research status of cloud top height and cloud base height,highlighted the load and products of FY-4A.(2)Principal component analysis and BP neural network were used to process the cloud top height,visible light reflectance and infrared brightness temperature measured by AGRI to retrieve the cloud base height of single-layer cloud.Based on the cloud base height obtained from the sounding data,the cloud base heights obtained by CloudSat and PCA-BP were compared,which verified the validity of the PCA-BP method to retrieve the cloud base height.(3)Based on the cloud top height acquired by CloudSat,quantitatively evaluate the cloud top height products obtained by FY-4A,and compare and analyze the probability distribution of the cloud top height in two ways.The latitude,different phase and the cloud top height of different layers of clouds are compared and analyzed.The results show that the cloud top height of FY-4A is consistent with the cloud top height of CloudSat,but the results of low latitude area and multi-layer cloud still need to be further improved.(4)Using the macroscopic and microscopic parameters such as cloud top height,cloud particle phase,cloud optical thickness,cloud effective particle radius and cloud water path acquired by AGRI,a random forest model is constructed,and the cloud base height of the single layer cloud is obtained by this retrival.Based on the cloud base height obtained from the sounding data,the cloud base height obtained by the CloudSat product and the random forest is compared and analyzed.The results show that the random forest method can effectively obtain the cloud base height information of the single-layer cloud,which has certain feasibility.