Joint SRNWP/COST-717 WG-3 session, Lisbon Stefan Klink Data Assimilation Section Early results with rainfall assimilation at DWD RADVOR-OP, supported by LAWA Joint SRNWP/COST-717 WG-3 session, Lisbon Early results with rainfall assimilation at DWD Radar data Real case study Humidity adjustment Filtering of vertical profiles Influence of convective parameterisation scheme Influence of mesh size Summary Joint SRNWP/COST-717 WG-3 session, Lisbon Radar data Input data currently used radar reflectivity at the ground (int. Composite: Germany and surrounding countries) pixel size: 4km 4km time resolution: 15 minutes (data from volume scan) conversion: reflectivity to precipitation rate by simple Z-R-relation problems: clutter, only 7 reflectivity classes Joint SRNWP/COST-717 WG-3 session, Lisbon Radar data new radar data input data: reflectivities from precipitation scan, mesh: 1km 1, time resolution: 5 minutes correction of orographic attenuation variable Z-R-relation compositing still incomplete clutter correction Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: experimental setup Convective event on 28. Aug over western Germany LM runs on the operational domain: mesh size 7 km LM runs on an experimental domain: covering almost Germany mesh size 2.8 km convective parameterisation scheme switched off laterally driven by GME 6h Nudging + LHN starting at 6 UTC adjustment of humidity during LHN 6h free forecast starting at 12 UTC operational domain (7 km) experimental domain (2.8 km) evaluation domain Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: humidity adjustment Increased heating increase q to reach f=100% over nudging timescale Reduced heating decrease q (maintain f) Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: humidity adjustment LM runs on the experimental domain: mesh size 2.8 km without humidity adjustment during LHN with humidity adjustment during LHN Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: humidity adjustment Hourly sums of modeled and radar- observed precipitation in mm/h Nudging UTC Nudging UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: humidity adjustment free forecast UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: filtering of vertical profiles vertical cross section W-E, t = 11 UTC, with humidity adjustment specific cloud liquid water content in g/kg no filtering filtering Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: influence of convective parameterisation scheme LM runs on the operational domain: mesh size 7 km no adjustment of humidity during LHN without convective parameterisation scheme with convective parameterisation scheme Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: influence of convective parameterisation scheme Hourly sums of modeled and radar- observed precipitation in mm/h Nudging UTC Nudging UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: influence of convective parameterisation scheme Nudging UTC free forecast UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Real case study: influence of convective parameterisation scheme free forecast UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Case Studies: comparison: mesh sizes 7 km and 2.8 km LM runs: CTRL 7 km: mesh size 7km (operational domain) LHN 7 km: mesh size 7 km (operational domain) LHN 2.8 km: mesh size 2.8 km (smaller model domain) Joint SRNWP/COST-717 WG-3 session, Lisbon Case Studies: comparison: mesh sizes 7 km and 2.8 km Hourly sums of modeled and radar- observed precipitation in mm/h Nudging UTC Nudging UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Case Studies: comparison: mesh sizes 7 km and 2.8 km Nudging UTC free forecast UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Case Studies: comparison: mesh sizes 7 km and 2.8 km free forecast UTC free forecast UTC Joint SRNWP/COST-717 WG-3 session, Lisbon Summary Results: adjustment of humidity supports the assimilation of precipitation and leads to more exact free forecasts explicit simulation of convection produces more realistic patterns and amounts of precipitation than the corresponding model run with a parameterisation scheme model with 2.8 km mesh size shows potential for further improvements of precipitation forecast sporadical occurrence of spurious precipitation influence of the assimilation lasts for several hours Joint SRNWP/COST-717 WG-3 session, Lisbon Summary Future work: numerical problems with noisy profiles of latent heat (2 z-structures) quality of radar data improvements to extend the influence of assimilation during free model run prognostic precipitation