Project Details
Projekt
Assimilation of polarimetric information and observation-based nowcasted fields in numerical weather prediction
Applicants
Professor Dr. Roland Potthast; Professor Dr. Clemens Simmer; Privatdozentin Dr. Silke Trömel, Ph.D.
Subject Area
Atmospheric Science
Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Term
since 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 320397309
RealPEP improves observation-based estimation (QPE, Project P1), nowcasting (QPN, Project P2) and numerical prediction of quantitative precipitation (QPF, this project P3) by exploiting information on micro- and macro-physical processes hidden in polarimetric radar and in satellite observations. Our goal is a significant improvement in quantitative precipitation forecasts by NWP, and thus in predicting discharge and potential flash floods in small- to meso-scale catchments (FFP, project P4). The predictive power of observation-based nowcasting rapidly decreases with forecast lead time due to missing physical constraints offered only by dynamical models, and due to the fundamental restriction caused by the limited lifetime of precipitating systems. This project will exploit along different pathways the extended information on cloud and precipitation states and processes in satellite and radar polarimetric observations as derived in P1 including tendencies and future states from P2 to achieve seamless precipitation prediction for about a day. We will extend data assimilation to satellite observations and radar polarimetry by (a) assimilating polarimetry-derived hydrometeor types and respective mixing ratios (cooperation C1, P1), by (b) assimilating predictive information including convection initiation extracted from observations (cooperation C1 and P2), by (c) directly assimilating - besides reflectivity and radial winds - polarimetric moments like differential reflectivity, specific differential phase, and cross-correlation coefficient, and by (d) extending the assimilation of observed states to nowcasted states (cooperation P2). The results of the different pathways will be evaluated in cooperation with P4 (FFP) for their added value in discharge and flash flood prediction. During Phase I of RealPEP the project will concentrate on pathways (a) – (c) while Phase II will finalize pathway (d) with the most successful variant(s) of (a) – (c). Our vision is to approach the replication of the observation-based 3D-composite by the NWP model to best serve high-resolution QPE, QPN and QPF.
DFG Programme
Research Units
