Fusion of Radar Polarimetry and Numerical Atmospheric Modelling Towards an Improved Understanding of Cloud and Precipitation Processes



Major objectives and visions

Cloud and precipitation processes are the main source of uncertainties in weather prediction and climate change projections since decades. A major part of these uncertainties can be attributed to missing observations suitable to challenge the representation of cloud and precipitation processes in atmospheric models. The whole atmosphere over Germany is since recently monitored by 17 state-of-the-art polarimetric Doppler weather radars, which provide every five minutes 3D information on the liquid and frozen precipitating particles and their movements on a sub-kilometer resolution, which is also approached by the atmospheric models for weather prediction and climate studies. Data assimilation merges observations and models for state estimation as a requisite for prediction and can be considered as a smart interpolation between observations while exploiting the physical consistency of atmospheric models as mathematical constraints. However, considerable knowledge gaps exist both in radar polarimetry and atmospheric models, which impede the full exploitation of the triangle radar polarimetry – atmospheric models – data assimilation and call for a coordinated interdisciplinary effort. The priority programme will exploit the synergy of the new observations and state-of-the-art atmospheric models to better understand moist processes in the atmosphere, and to improve their representation in climate- and weather prediction models. The programme will extend our scientific understanding at the verges of the three disciplines for better predictions of precipitating cloud systems by addressing the following objectives:

Objective 1: Exploitation of radar polarimetry for quantitative process detection in precipitating clouds and for model evaluation

Polarimetry Influenced by CCN aNd INP in Cyprus and Chile (PICNICC)
Joint project between Leibniz-Institute for Tropospheric Research (TROPOS) and University of Leipzig

Investigation of the initiation of convection and the evolution of precipitation using simulations and polarimetric radar observations at C- and Ka-band (IcePolCKa)
Joint project between Uni Bonn and Deutsches Zentrum für Luft- u.Raumfahrt(DLR), Ludwig-Maximilians-Universität (LMU)

A seamless column of the precipitation process from mixed-phase clouds employing data from a polarimetric C-band radar, a microrain radar and disdrometers (HydroColumn)
Project at Deutscher Wetterdienst - Observatorium Hohenpeißenberg

Investigating the impact of Land-use and land-cover change on Aerosol-Cloud-precipitation interactions using Polarimetric Radar retrievals (ILACPR)
Project by University of Bonn

An efficient volume scan polarimetric radar forward OPERAtor to improve the representaTION of HYDROMETEORS in the COSMO model (OPERATION HYDROMETEORS)
Joint project between University of Bonn and Deutscher Wetterdienst

Polarimetric signatures of ice microphysical processes and their interpretation using in-situ observations and cloud modeling (POLICE)
Joint project between University of Bonn and University Mainz

Understanding Ice Microphysical Processes by combining multi-frequency and spectral Radar polarImetry aNd super-parTicle modelling (IMPRINT)
Joint project between Deutscher Wetterdienst, DWD and University of Cologne

Web-based radar data portal fort the access of archived radar data Web-based radar data portal
Project based at Deutscher Wetterdienst (DWD)

Objective 2: Improvement of cloud and precipitation schemes in atmospheric models based on process fingerprints detectable in polarimetric observations

Understanding Ice Microphysical Processes by combining multi-frequency and spectral Radar polarImetry aNd super-parTicle modelling (IMPRINT)
Joint project between Deutscher Wetterdienst, DWD and University of Cologne

Investigating the impact of Land-use and land-cover change on Aerosol-Cloud-precipitation interactions using Polarimetric Radar retrievals (ILACPR)
Project by University of Bonn

Evaluating and Improving Convection-Permitting Simulations of the Life Cycle of Convective Storms using Polarimetric Radar Data (Life Cycle of Convective Storms)
Project by Karlsruhe Institute of Technology

Spectrally resolved Polarimetric Observation and Computation of Clouds (SPOCC)
Project by TROPOS

Climate model PArameterizations informed by RAdar (PARA)
Joint project between University of Bonn and University of Leipzig

Objective 3: Monitoring of the energy budget evolution due to phase changes in the cloudy, precipitating atmosphere for a better understanding of its dynamics


Polarimetry Influenced by CCN aNd INP in Cyprus and Chile (PICNICC)
Joint project between Leibniz-Institute for Tropospheric Research (TROPOS) and University of Leipzig

Evaluating and Improving Convection-Permitting Simulations of the Life Cycle of Convective Storms using Polarimetric Radar Data (Life Cycle of Convective Storms)
Project by Karlsruhe Institute of Technology


Objective 4: Generation of precipitation system analyses by assimilation of polarimetric radar observations into atmospheric models for weather forecasting


Representing model error and observation Error uncertainty for Data assimilation of POLarimetric radar measurements (REDPOL)
Joint project between Ludwig Maximilians University (LMU) of Munich and Deutscher Wetterdienst (DWD)

An efficient volume scan polarimetric radar forward OPERAtor to improve the representaTION of HYDROMETEORS in the COSMO model (OPERATION HYDROMETEORS)
Joint project between University of Bonn and Deutscher Wetterdienst

Objective 5: Radar-based detection of the initiation of convection for the improvement of thunderstorm prediction


Investigation of the initiation of convection and the evolution of precipitation using simulations and polarimetric radar observations at C- and Ka-band (IcePolCKa)
Joint project between Uni Bonn and Deutsches Zentrum für Luft- u.Raumfahrt(DLR), Ludwig-Maximilians-Universität (LMU)

A Low-cost Mechanically-Steered Phased-Array Polarimetric Doppler Weather Radar (Polarimetric Phased-Array Radar)
Project by Fraunhofer-Institut für Hochfrequenzphysik und Radartechnik FHR

Representing model error and observation Error uncertainty for Data assimilation of POLarimetric radar measurements (REDPOL)
Joint project between Ludwig Maximilians University (LMU) of Munich and Deutscher Wetterdienst (DWD)