Extracting winter wheat area using temporal sequence of Ts-EVI

Winter wheat is one of the most important crops in China. It is significant to extract winter wheat area accurately using remote sensing technology because area information can be used for monitoring growth condition and estimating yield. In this study, temporal series of MYD09A1 and MYD11A2 productions provided by NASA from February to June in 2005 were used to establish temporal sequence of Ts-EVI. Variation characteristics of winter wheat phenology were analyzed and the method to extract winter area using temporal sequence of Ts-EVI was also discussed. Results show that: (1) winter wheat has the particular temporal sequence characteristics in Ts-EVI space. Ts of winter wheat rises with the time after the greenup and EVI increases before heading and milking stages then begins to descend; (2) one dimensional treatment was done for Ts-EVI space information and principal component analysis was used to reduce the dimensions of temporal sequence images, then ISODATA, the unsupervised method was used to extract winter wheat area. The accuracy of classification of winter wheat tested with in situ samples was 91.20%; (3) it is definite to express the physiological meaning with temporal sequence of Ts-EVI. Remote sensed classifying method with temporal sequence of Ts-EVI can extract winter wheat successfully, which shows great feasibility.