|Deutsches Zentrum für Luft- und Raumfahrt |
Institut für Physik der Atmosphäre (IPA)
Project team: George Craig, Hartmut Höller, Thorsten Fehr
The Instiut für Physik der Atmosphäre, DLR, has a long-standing experience in thunderstorm research. The experimental tools include research aircraft (DLR Falcon-E20), polarimetric Doppler radar (POLDIRAD) with a network of bistatic receivers, lightning detection network (LINET) and water vapor DIAL and Doppler wind Lidar systems. Along with numerical models, (DWD-Lokal-Model), for simulating thunderstorms and convective systems, these provide an ideal research background for field investigations of convective processes.
Many aspects of deep convection will be addressed by the DLR: The upward moisture flux in the planetary boundary layer (PBL) is a crucial limiting factor for the initiation of convection. The DLR will provide simultaneous airborne lidar measurements of the PBL water vapor distribution and wind field. From these observations an estimate for the water vapor flux can be derived. Following an initial study with data from the IHOP field campaign (Fig. 1), the DLR water vapor DIAL and the 2µm Doppler wind lidar onboard the DLR Falcon aircraft will take part in the COPS/QPF field campaign adding a dataset to the COSI-TRACKS project.
The potential of convection to develop into a severe storm, producing adverse weather conditions like heavy rain, hail, lightning, and damaging winds, will be investigated using radar and lightning measurements. The microphysical processes leading to extreme storm conditions will be investigated using the DLR POLDIRAD at Oberpfaffenhofen. In combination with lightning measurements from existing systems and the new DLR LINET (Fig. 2), storm mechanisms with the potential of predictive indicators will be identified for several case studies. In addition, the DLR will provide LINET lightning data and radar information from field campaigns in tropical regimes, e.g., for southern Brazil during TROCCINOX (Jan./Feb. 2005) and West Africa during AMMA (June/July 2006).
The prediction of convective storms in numerical models will be addressed using ensemble forecasts. Due to their small size and rapid development severe thunderstorms are inherently difficult to predict. Ensemble forecasts provide a promising way to give a probabilistic guidance in convective situations. A prototype ensemble system based on the German Weather service Lokal-Model is being developed at the DLR. The model uses the operational horizontal resolution of 7 km. A new stochastic convective parameterization will be added to the system during COSI-TRACKS. The effects of this new parameterization on ensemble spread and predictive skill will be verified using the results from the observational case studies using synthetic satellite (Fig. 3) and radar data.