基于MODIS EVI图像时间序列的冬小麦面积提取

植被指数的时间序列能够很好的反映植被在时间维上的生长变化，这为地表植被的分类以及作物面积的提取提供了思路。将TM数据作为过渡数据，利用地面测量数据间接对MODIS EVI数据进行了样本提取和验证，并结合冬小麦物候信息，将冬小麦植被指数时间曲线参量化为生长速率、衰减速率和峰值与休眠期比值，建立了华北平原冬小麦的面积提取模型。经验证，兖州地区MODIS数据和TM数据提取的冬小麦面积一致性为89.13%，整个华北地区选取13县市的MODIS提取面积与官方统计数据比对，表明有12县市的提取误差小于20%，误差主要源于MODIS的空间分辨率较粗而华北平原的地块较为细碎。

Winter wheat planting area extraction based on MODIS EVI image time series

The vegetation index time series can reflect the growth changes of the vegetation in the time dimension, and this provides a potential way for the land cover classification and cropland area extraction. The field survey data were used to extract sample and validate for MODIS EVI data indirectly by using TM data as the transition data. Considering the winter wheat phenological calendar, the identifiers of winter wheat were parameterized as growth rate, declining rate, ratio of peak to dormancy, and then the winter wheat area of Huabei Plain was extracted. The extraction result was quite consistent with TM-based result with a precision of 89.13%. For the whole Huabei Plain, twelve out of 13 selected counties/cities had errors less than 20% than those from the official statistics data. The errors were caused mostly by the coarse resolution of MODIS and the smaller area of cropland of Huabei Plain.