A PRELIMINARY STUDY OF FOURIER SERIES ANALYSIS ON CLOUD TRACKING WITH GOES HIGH TEMPORAL RESOLUTION IMAGES

Fourier series analysis is proposed as a new technique to address the problem of"sub-pixelmotion"in deriving cloud motion winds(CMW)from high temporal resolution images.Based on aconcept different from that of maximum correlation matching technique,the Fourier technique computes phase speed as an estimate of cloud motion.It is very effective for tracking small cellularclouds in 1-min interval images and more efficient for computation than the maximum correlation technique because only two templates in same size are involved in primary tracking procedure.Moreover it obtains not only CMW vectors but potentially also velocity spectrum and variance.Apractical example is given to show the cloud motion winds from 1-min interval images with the Fourier method versus those from traditional 30-min interval images with maximum correlation technique.Problems that require further investigation before the Fourier technique can be regardedas a viable technique,especially for cloud tracking with high temporal resolution images,are alsorevealed.