3�C11.3 ��m; IR2, 11.5�C12.5 ��m and WV 6.3�C7.6 ��m) from China��s first BTB06584? operational geostationary meteorological satellite FemgYu-2C (FY-2C). FY-2C was launched successfully from Xichang city, Sichuan Province, China on October 19, 2004. The present operational cloud classification product of FY-2C is based on a clustering method and uses 32 �� 32 pixels window as basic classification unit. This method uses single Infrared channel (IR1) data to detect clouds, then use Inhibitors,Modulators,Libraries Tbb gradient of WV channel to classify high-level clouds. It provides unrealistic cloud edges at two adjacent windows due to its large classification unit (32 �� 32 pixels). It has limited capacity in identifying low-level cloud and thin cirrus from underlying surface, because it does not make use of FY-2C multi-Infrared split window information which is proved to be useful in cloud detection.
At present, no other more sophisticated cloud classification methods are used in FY-2C operational products. Therefore Inhibitors,Modulators,Libraries one overarching goal of this study is to identify more Inhibitors,Modulators,Libraries suitable techniques for the multi-channel cloud image classification in order to upgrade the currently use of FY-2C. Results of this study will also help choosing automated cloud classification algorithms for the upcoming launch of the FY-4 series . This paper is organized as the follows. Section 2 introduces the FY-2C images and data. Section 3 provides a brief description of the classification methods. In Section 4, the capability of ANNs is demonstrated and compared with two other traditional classification methods and the current FY-2C operational classification method at two levels: pixel level and image level.
The discussions and summary are given in Section 5.2.?Data2.1. Satellite DataFY-2C is positioned over the equator 105�� E, and carries VISSR (Visible and Infrared Spin Scan Radiometer). Its nadir spatial resolution is 1.25 km for visible channel, and 5 km for Inhibitors,Modulators,Libraries infrared channels (Table 1).Table 1.Specifications of VISSR channels: spectral range and spatial resolutions.According to the remote sensing characteristics, FY-2C split window (IR1, IR2) can discriminate underlying surface and cloud area. The water vapor channel (WV) can indicate the height of clouds well. VIS is useful for the detection of low clouds, but it is not accessible at night. IR4 is sensitive to objects with higher Entinostat temperature.
It is usually used for the estimation of underlying surface temperature and detection of fog and low-level clouds. However, great efforts are needed to eliminate the influence of visible light on the Tbb of IR4 channel . To develop an automatic cloud classification system by which clouds in daytime and night can be compared, this study chooses three infrared channels promotion information data: IR1, 10.3�C11.3 ��m; IR2, 11.5�C12.5 ��m; WV 6.3�C7.6 ��m.2.2.