This article is composed of three parts . In the first part, we introduced 1-D Fourier technique to calculate the velocity of the wind , and analyzed the error in tracking cloud motion by 1-D Fourier technique. Because of the problem of "sub-pixel motion", it is difficult to deduce the accurate cloud motion winds (CMW) from high temporal resolution images by the maximum correlation technique. By 1-D Fourier transform, we could analyze wave spectrum and get wave speed by computing phrase shift, then calculate the velocity of the wind , so we can avoid the problem of "sub-pixel motion". 1-D Fourier technique is Based on 1-D moving supposition, but cloud motion is not only horizontal but also vertical, so the error would come into existence. The error in tracking cloud motion by 1-D Fourier technique was analyzed.In the second part, 2-D Fourier technique was put forward. 2-D Fourier technique could compute horizontal and vertical speed of cloud motion in the same time, so it can avoid the error caused by 1-D moving supposition in the 1-D Fourier technique. In this part, the 2-D Fourier technique theory was introduced, and a numerical simulation was given in this paper.In the third part, we compared the 2-D Fourier technique with the 1-D Fourier technique, analyzed their problems and found ways to resolve them. |