An analysis of a pressure pattern in severe Typhoon Bart hitting the Japanese Islands in 1999 and a comparison of the gradient wind with the observed surface wind

Typhoon Bart (T9918) hit Kyushu in Japan on September 24 in 1999, and caused storm surge at Matsuai-area of Shiranui in Kumamoto Prefecture with 12 deaths. We analyzed the pressure pattern in Typhoon Bart by an objective method and computed the gradient wind from it. The computed wind was compared with the wind observed at the sites of the Network for Wind Measurement in Kyushu (NeWMeK) system. The ratio of the observed wind speed to the gradient wind speed was about 0.5 outside of the maximum wind radius, but it increased rapidly with the decrease of relative radius inside of it. In addition to wind data at six stations of the Japan Meteorological Agency, the wind ratio outside of the maximum wind radius increased with height in proportion to 0.33 power of the anemometer height.