抄録
It is generally desired to estimate wind aloft by the use of satellite successive images of clouds and this estimate is called "cloud motion wind" (CMW). The CMW, however, has been known sometimes very erroneous. This paper aims to estimate the causes of error statistically and analytically, and to improve the CMW.
It is found that most of the wrong CMWs aloft are associated with the jet stream, the local steep slope in the tropopause and the frontal layer frequently appearing just below the jet stream core.It should be noted that, related to the meteorological features stated above, slight failure in assigning the cloud height would give larger error to the CMW.
Based on those findings, the original CMW data are applied a kind of quality control and modified with the help of winds observed by rawinsonde, if available. With this method, the errors are found to be about 8m/s, on the average, though they are about 12m/s without this.
