Prediction of probability distribution of Tropical Cyclone trajectories under future climate around Japan

Extreme events such as severe storms, tropical cyclones, and floods, could have serious risks and influences on the human life under the climate change. Our study assesses probability distribution of trajectories of tropical cyclones (TCs) that attack Japan under future climate. It is challenging, so we divide this subject into two problems. The first one is about the TC formation and an uncertainty for its position. The uncertainty of the initial position of a TC is represented by a statistical model based on the atmospheric and oceanic background. The second one is about TC tracks. In the present study, we express probability distribution of TC trajectories estimated on the basis of reanalysis data and GCM output. The TC trajectories are mainly controlled by the atmospheric circulation such as the trade winds and the Westerlies as well as are influenced to move northward by the Beta effect. The trajectories calculated with trajectory analysis would thus correspond to the movement of TCs due to the atmospheric circulation. Comparing the result of the trajectory analysis from reanalysis data with the Best Track (BT) of TC in the present climate, the structure of the trajectory seems to be similar to the BT in the lower and middle troposphere. We are going to assess the probability distribution of the TC trajectories adapted with BTs and apply the method for the estimation of the TC trajectories under the future climate where no BT.