Directional characteristics of probability distribution of extreme wind speeds by typhoon simulation

Wind directional fluctuations under typhoon condition was studied on the basis of its effect on the directional probability of annual maximum wind speed. A typhoon model that accurately models the average field observations, underestimates the maximum wind speed. Thus, a probability method is proposed for accurately evaluating the maximum wind speed probability distribution. This probability method is extended to corporate wind directional fluctuations. Before modeling is carried out, uncertainties are divided into physical and other conditions. The physical variation of wind direction is modeled probabilistically as directional fluctuations, and its formula is shown. Other uncertainties include statistical uncertainty (e.g., sampling error), modeling uncertainty and measurement error. These uncertainties are modeled considering two general situations: the maximum uncertain situation, where wind speed is used regardless of its direction, and minimum uncertain (definite), where wind direction is accurately evaluated. Taking these situations into account, a directional wind speed evaluation was formulated. Effects of physical wind directional fluctuations and wind directional uncertainties are indicated as a small increase in wind speeds for long-term wind speed recurrence. More effects were shown in the shorter return period range. (C) 2002 Elsevier Science Ltd. All rights reserved.