报告题目：Data Assimilation of Nowcasted Observations

报告专家：Prof. Dr. Roland Potthast

报告时间：2023年10月26日（周四）16:00

会议形式：Webex-线上会议（会议ID: 27441291796）

会议链接：https://yuefeizeng.my.webex.com/meet/pr003558（电脑浏览器直接进入，无需密码)

主 持 人：曾跃飞 教授

专家简介：

Prof. Dr. Roland Potthast is the director for Numerical Weather Prediction at Deutscher Wetterdienst (DWD) and Professor for Applied Mathematics at the University of Reading with research in inverse problems and data assimilation. At Deutscher Wetterdienst he is responsible for a group of more than 30 researchers which work on global and high-resolution atmospheric forecasting, which includes dynamical uncertainty estimation based on ensemble data assimilation and forecasting methods.

报告摘要：

DWD works on the integration of classical nowcasting with classical forecasting. One basic question linked to this integration asks: is it possible and useful to assimilate nowcasted observations into the numerical model for atmospheric prediction？ We study both an oscillator model and the Lorenz 63 model with assimilation based on the Localized Ensemble Transform Kalman Filter (LETKF). We investigate and provide a mathematical framework for the assimilation of nowcasted information, approximated as a local tendency, into the LETKF in each assimilation step. In particular, we derive and discuss adequate observation error and background uncertainty covariance matrices and interprete the assimilation of nowcasted information as assimilation with an L1-type metric in observation space. Further, we show numerical results which prove that nowcasted information in data assimilation has the potential to significantly improve model based forecasting.

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气象灾害教育部重点实验室

气象灾害预报预警与评估协同创新中心

南京信息工程大学大气科学学院

2023.10.24