由于众所周知的原因,依靠逐级层层上报的统计数据是不可能获得准确的冬小麦播种面积数据的,所以人们曾寄希望于借助遥感手段去解决问题。然而一个基本困难是:冬小麦的主要生长期仅一百余天,在这样短的生长期内,如果依靠地面分辨率较高的TM或SPOT卫星数据,那么由于它们的重复周期较长,不可能覆盖象一个省那样大的范围,只能获得个别地 Due to well-known reasons, it is impossible to obtain accurate winter wheat sown area data by relying on the statistical data reported step by step, so people have placed their hopes on solving the problem by means of remote sensing. However, one of the basic difficulties is that the main growth period of winter wheat is only one hundred days. In such a short period of growth, it is impossible to rely on TM or SPOT satellite data with a higher ground resolution because of their longer repetition period Coverage as large as a province can only be obtained individually