Research And Application On Key Technology Of Snow Cover Extractation In Tibetan Plateau Based FY-3/VIRR Data

Snow is an important type of land and sea-ice surface, and the change of snow coverage have much impact on energy exchange of land surface,climate change and hydrological processes, which is very active in nature. Tibetan Plateau, one of China’s three major snow area, is located in the middle and low latitudes in the Northern Hemisphere. The distribution of snow can influence local and national climate change, even in the other global regions. Snowstorm can cause economic losses to local animal husbandry. Therefore, it is important to monitor the snow cover of Tibetan Plateau, and the use of foreign satellite data was in most cases. But remote sensing capabilities of domestic satellite has been improved continually, and product independent data. In this paper, with Tibetan Plateau for the study region, and domestic satellite data for research data, we research from the establishment of model about Identification of snow pixel, accurate snow cover extractation, analysis of the temporal and spatial variation characteristics of snow cover, snow cover information automatic extraction system, and so on. It provides a scientific basis for analysis of snow conditions and disaster prevention and mitigation, reduce the economic loss of animal husbandry, and promote the development of Meteorological Service.Firstly, we use domestic self-developed FY-3/VIRR data as the primary research data, snow depth ground weather observation data as the validation data, and daily snow cover of MODIS as the comparative data. According to the visible light reflectance and infrared brightness temperature characteristics of the snow, cloud and various other objects in different bands, we propose a general method of identifying snow pixel with multi-channel by dynamic threshold. Through many examples, it proves that the algorithm is reasonable and feasible. Then, extracting the information of snow cover in Tibetan Plateau Based this method, and product snow cover data set of Tibetan Plateau for analysis of the temporal and spatial variation characteristics of snow cover. Finally, in order to meet the massive remote sensing data processing and business development needs, we design and development an automatic system for snow cover information extraction based on hybrid programming technology of IDL and C#.The main research results of this paper can be summarized as follows:(1) A general method of identifying snow pixel with multi-channel by dynamic threshold based on FY-3/VIRR data was proposed. Research shows that the algorithm is reasonable and feasible, and easy to realize. FY-3/VIRR data is a kind of reliable data source to extract snow information. This research has certain theory and business application value.(2) It is the first time using this method to extract snow cover information of Tibetan Plateau with effective threshold, and product snow cover data set of Tibetan Plateau from 2009 January to 2014 April for analysis of the temporal and spatial variation characteristics of snow cover in annual distribution, multiyear variation and different height. It can provide some comprehensive decision-making guidance for the meteorological service.(3) On the basic of theoretical research, in order to meet the massive remote sensing data processing and business development needs, we design and development an automatic system for snow cover information extraction based on hybrid programming technology of IDL and C#. This system has a powerful function, friendly interface, convenient operation, fast processing speed,which prompt data of domestic satellite to be fully applied and spread.