Probability forecast of storm surge levels in the Changjiang Estuary induced by tropical cyclones based on the Error-Estimation Ensemble method

Abstract

This paper proposed a probability forecast methodology for the storm surges induced by tropical cyclones, including a probability forecast method of tropical cyclone tracks and a probability forecast scheme of storm surge levels. The probability forecast method of tropical cyclone tracks is developed based on the Error-Estimation Ensemble (EEE) method. Empirical distributions of the positions of the tropical cyclone centers around the EEE-forecasted ones are gained and used to make probability forecast of tropical cyclone tracks. It performs well in hindcasting the tropical cyclones that moved in the 24-h warning line of China in 2018. The probability forecast of storm surge levels is based on the probability forecast of tropical cyclone tracks. Under a given target fall-in probability, five possible tracks are used to drive the storm surge model and yields five forecasts of storm surge levels, the envelope of which is taken as the possible variation range of water level under the target fall-in probability. Using the probability forecast method, six launches of the probability forecast of three typical storm surges that affects the Changjiang Estuary are conduced, and the performance of the probability forecast method is assessed via a comparison between the target and realistic fall-in probabilities.