Assimilation and Process Studies for selected COPS IOPs using GPS STD and radar radial velocities in the WRF-Var system (APRO-GRAVAR)

• Applicants: Dr. Hans-Stefan Bauer; Professor Dr. Jens Wickert
• Subject Area: Atmospheric Science
• Term: from 2010 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 175716011

This work applies observations of the field experiment COPS where GFZ collected a unique, real-time GPS data set (STD, ZTD, IWV), which was re-processed and extended during the last two years. Furthermore, radar radial velocities from the German radar network as well as in-situ observations from the ECMWF MARS archive will be included into the investigations.It shall be demonstrated by IPM that advanced data assimilation systems combined with the dense COPS data set are capable to construct accurate initial states so that the evolution of the 4D thermodynamic state in complex terrain can be simulated in dependence on largescale forcing mechanisms. Particularly interesting are the formation of thermally induced upslope flows and mesoscale vortices. These are expected to play a key role for the formation of convergence lines and convection initiation. Furthermore, shallow and deep convection and its organization shall be investigated as well as the performance of e.g. different parame-terizations of the atmospheric boundary layer and cloud microphysics.Another key topic is the demonstration of the value of the high-resolution observations for validation and model improvement purposes. Comparisons of high-resolution simulations and observations collected during COPS shall reveal systematic model errors paving the way to improve parameterizations.The work in the field of GPS meteorology will be continued by validating the improved GPS processing strategies developed at the GFZ in the preceding COPS-GRID project. Extensive validation studies based on water vapor radiometers, radiosondes and analyses of numerical weather models (ECMWF, COSMO) will provide the error characteristics of the slant total delays. These results are not only required by the data assimilation studies described above but will also be used to refine the processing algorithms. The stages of the GPS processing procedure will be investigated separately in order to validate all quantities contributing to the slant total delay, e. g. the dry and wet zenith delays, the atmospheric gradients and the residuals. The required observations will be taken from the COPS database, the COPS-COSMO-reanalysis currently carried out by the DWD and ECMWF data.The near real-time data processing and the reprocessing of the COPS GPS data set will be continued in order to extend the GPS networks and to provide most reliable GPS observations processed with the latest version of the GPS processing software.

• DFG Programme: Research Grants
• Participating Persons: Dr. Gerd Gendt; Professor Dr. Volker Wulfmeyer