Joint Centre for Mesoscale Meteorology (JCMM)
Fourier series analysis is proposed as
a new technique for deriving cloud motion winds from high temporal resolution
satellite images. Based on the change of harmonic phase, the Fourier
technique computes phase speed as an estimate of cloud motion. A
speed spectrum is also derived, the standard deviation of which might provide
information on speed difference of clouds in different scales in an analysed
area if contribution from noise could be removed. A practical example
shows the ability to obtain more extensive and detailed cloud motion winds
from high temporal resolution images with the Fourier method than from
traditional 30-minute interval images with maximum correlation technique.
It also reveals problems of noisy wind fields that require further investigation
before the Fourier technique can be regarded as a viable technique.