Wind structure analysis of the 0903 typhoon Linfa

Due to the lack of real-time observation data when typhoon is in the sea and the influence of landscape on typhoon after it lands,analysis of the overall inner wind structure of typhoon has always been difficult to conduct.However,as for those typhoons moving along the coast,wind structure analysis is possible as the effect of landscape on them is little and hourly updated data are available from coastal areas automatic stations.Through analyzing the hourly data from coastal automatic stations after typhoon Linfa landed at Jinjiang in Fujian Province and moved northwards along the coast,we studied the wind structure of 0903 typhoon Linfa and made the following conclusions:(1)The forcasted maximum wind speed of near typhoon center was lower than the observed wind velocity,and the forcasted seven-wind circle radii was longer than the observed data.(2)In general,the observed 2 min maximum wind velocity in every hour weakened with time-dependant correlation equation of vmax=28.9-0.61t(n=16,r=0.78,r0.05=0.50).(3)The maximum wind velocity radii of typhoon showed a trend of enlargement with time-dependant correlation equation of R=28.28-4.98t+0.67t2(n=16,r=0.95,r0.05=0.50).(4)The area of maximum wind velocity was at the back of typhoon.Understanding the wind structure of typhoon will help improve forecasting accuracy.