A Study on Relations between the Occurrence of Strong-wind and the Boundary from the Water Vapor Satellite Images

The boundary area between the bright and dark side from water vapor satellite images is the air mass with a different moisture condition at the middle-upper layer. Spatially, the degree of contrast between the bright and dark side increases with the significant change of moisture, producing boundaries. Based on Weldon and Holmes's boundary classification system, a base surge boundary and a head boundary can be used for analyzing strong-wind.

According to the case used in this study, base surge boundaries were formed when strong winds occurred, and enhanced the northward winds. In this case, head boundaries were also developed and contributed to the enhancement of wind speed. In addition, by tracking the shape of head boundaries which represents the degree of intensity, the change of wind speed could be predicted. Furthermore, by tracing the shape of cloud on the water vapor satellite images, the direction and timing of strong wind shift could be predicted. With this pattern, the wind speed increases with the elevation. However, when the head boundary was only formed (base surge boundary was not formed), strong wind did not occur, and wind speed did not increase with elevation as well.

In brief, by tracking base surge boundaries and head boundaries from water vapor satellite images, qualitative analysis of wind speed at the higher and lower layer might be possible, and this in turn can provide fundamental information on wind forecast, especially wind warning and advisory.