1:45 PM - 3:15 PM
[AAS04-P04] Detection of complex moving typhoons using steering angle
Keywords:typhoon
Forecasting typhoon tracks is significant from the viewpoint of disaster prevention, because the damage area of a typhoon depends greatly on the typhoon track. Although the accuracy of typhoon track forecast is improving year by year on average, it is often difficult to forecast typhoons with complex track patterns (hereafter “stray typhoons”). It may be possible to improve forecast accuracy for stray typhoons by identifying the conditions that cause their complex movements and understanding their effect on typhoon tracks.
However, there is no established quantitative definition of a stray typhoon, making statistical analysis difficult.
In this study, we aim to quantitatively define and extract stray typhoons to statistically analyze the environmental conditions required for stray typhoons to exist. To extract stray typhoons, a numerical value called steering angle is introduced. Steering angle represents how much the steering wheel is turned from the perspective of the “driver” of a typhoon. When the typhoon passes through coordinates P(n), P(n+1), and P(n+2) every 6 hours, the steering angle is defined as the angle changed from path P(n) → P(n+1) to path P(n+1) → (n+2).
Next, we excerpt stray typhoons using this steering angle based on observations. We identify 31 stray typhoons, whose absolute value of the steering angle is in the top 1%, the maximum wind speed exceeds 25 m/s, and the velocity of movement exceeds 5 kt. We will also discuss the usage of these indices to determine the large-scale field preferable for the existence of stray typhoons.
However, there is no established quantitative definition of a stray typhoon, making statistical analysis difficult.
In this study, we aim to quantitatively define and extract stray typhoons to statistically analyze the environmental conditions required for stray typhoons to exist. To extract stray typhoons, a numerical value called steering angle is introduced. Steering angle represents how much the steering wheel is turned from the perspective of the “driver” of a typhoon. When the typhoon passes through coordinates P(n), P(n+1), and P(n+2) every 6 hours, the steering angle is defined as the angle changed from path P(n) → P(n+1) to path P(n+1) → (n+2).
Next, we excerpt stray typhoons using this steering angle based on observations. We identify 31 stray typhoons, whose absolute value of the steering angle is in the top 1%, the maximum wind speed exceeds 25 m/s, and the velocity of movement exceeds 5 kt. We will also discuss the usage of these indices to determine the large-scale field preferable for the existence of stray typhoons.