Large Ensemble Data Assimilation Experiment
The ensemble weather forecast data is the critical starting point for everything in this project. The data assimilation team creates extensive ensemble weather forecast data of more than 1,000 members through data assimilation and provides it to the mathematical research team. In addition, the team back-projects the control input obtained by the mathematical research team to the meteorological field and verifies the controllability.
The left figure is an ensemble forecast of Typhoon LIONROCK (track prediction), which made landfall in the Tohoku region after a complicated track in August 2016. For this typhoon LIONROCK has advanced to the start point of the forecast (start time), it’s subsequent paths are estimated using an ensemble forecast method. For this typhoon, the ensemble predictions are split left and right. In other words, it is an example of a typhoon whose course is difficult to predict.
The data assimilation research team conducts extensive ensemble forecasts of over 1,000 members. Preparing a vast amount of weather forecast data contributes to the identification of adequate control inputs for the weather by the mathematical research team. In addition, the group supports the quantification research of damage reduction effects by the economic damage research team. Using various tools such as machine learning, the data assimilation research team itself also works on enhancing ensemble data assimilation techniques.
Details of the "ensemble forecast" can be found on the Japan Meteorological Agency website, for example, https://www.jma.go.jp/jma/kishou/know/whitep/1-3-8.html.