Estimates of gust wind speeds in Kyushu area for a wind hazard map

(1)利用拥有122个测站的九州测风网1994-2002年的资料和各地形的数字信息，研究了平均风速在15m/S以上的阵风因子的特征。各测站资料按台风或非台风、16个风向、气象条件和地形地貌排列。(2)台风阵风因子高于非台风，台风为1.9，非台风为1.7。台风来临时，即使平均风速较高，阵风因子也不会减小。因此，最大阵风速度估计是更高的风速。此外，南风的最大阵风远大于北风。(3)通过风洞试验研究了熊本县石井町的风速增长特性。结果表明，临近风廓线的温度梯度对低层风的增加有很大的影响。分层风流的稳定性通过位于风洞表面的干冰盒冷却平板来增强。然而，在深河、深谷底这样的混合区，很难估计当地的风速。(4)大多数基于台风巴特(1999)破坏的民居信息的住宅损伤率与风速之间的关系的调查表明，与瞬时风速的关系更明确。当风速超过30m/S时，损伤率呈指数增加。此外，在风速超过35m/S的情况下，风速的持续时间对灾害率的影响很大。(5)我们结合我们的阵风因子信息和百年重现期的预期风速图，生成了九州的瞬时最大风速图。该风速图适用于民居和建筑物风险图的绘制。

(1) The properties of the gust factors of mean wind speed of over 15 m/s were investigated based on the data of the network of wind measurement in Kyushu (NeWMeK) from 1994 to 2002, which has 122 measurement stations, and the digital information of each terrain. The data of each station are arranged by typhoon or non-typhoon, 16 directions of wind, its weather condition and its topography of terrain.(2) It is indicated that the gust factors in typhoon are higher than those in non-typhoon: 1.9 in typhoon and 1.7 in non-typhoon. When typhoon approaches, the gust factor does not decrease even though the mean wind speeds are high. And so a maximum gust speed is estimated to be a much higher wind speed. Moreover, the maximum gust is much higher in southern wind than in northern wind.(3) The property of increase of wind speed at Shiranui-cho of Kumamoto prefecture was investigated by wind tunnel test. It is found that the temperature gradient of the approaching wind profile affects strongly the increase of wind in the lower layer. The stability of a stratified wind flow is enhanced by a cooled plate using a dry-ice box located at the wind tunnel surface. However, it is difficult to estimate the local wind speed in a mixed area such as a deep river and a deep valley floor.(4) Most of the investigation of the relationship between residential damage rates and wind speeds based on information of damaged residential houses by Typhoon Bart(1999) indicate clearer relation to a instantaneous wind speed. For wind speeds of exceeding 30 m/s, the damage rate exponentially increases. In addition, the duration of wind affects strongly the damage rates in case of wind speeds of over 35 m/s.(5) We have produced the instantaneous maximum wind speed map of Kyushu, by combining our information of gust factors and the map of expected wind speeds for a return period of a hundred years. This wind speed map is applicable to suggest a wind hazard map of residential houses and buildings.