1. COSMO model simulations for COPS IOP 8b, 15 July 2007 Jörg Trentmann, Björn Brötz, Heini Wernli Institute for Atmospheric Physics, Johannes Gutenberg-University Mainz, jtrent@uni-mainz.de Introduction: The Convective and Orographically-Induced Precipitation Study (COPS) was designed to investigate the initiation of deep convective in mountainous terrain. On 15 July 2007, during COPS IOP 8b, a single cell convective storm that lasted for about one hour formed within the COPS area. The objective of the present work is to evaluate the performance of the COSMO model for this event using observations obtained within COPS and to identify deficiencies in the model. On 15 July the COPS region was under the influence of the warm air region associated with a surface low west of Great Britain. High pressure was present over south-east Europe. Shallow cumulus clouds formed in the late afternoon in the COPS region. Conclusions and Outlook: The representation of meteorological conditions on 15 July 2007 during COPS IOP 8b in the COSMO model is investigated. Operational forecast using the COSMO model did not predict the initiation of the single convective cell. The convective cell was captured by the operational forecast of the AROME model. ‘Tuning’ of the COSMO model by using different initial and boundary conditions and modified physical parameterizations did not improve the simulations. An evaluation of the model simulations with observations obtained within COPS (e.g., radiosoundings, GPS-derived moisture field) showed that the model underestimates the low level humidity. In further studies we will extend the model evaluation by using additional COPS data, e.g., from ground-based and airborne lidar. Operational Forecasts COSMO-DE (6 UTC) AROME (0 UTC) ALADIN (0 UTC) COSMO-CH2 (6 UTC) Data provided by Matthias Zimmer from MAP D-PHASE archive. Synoptic Situation MODIS true color image, 15 July 2007 The COSMO Model ModelCOSMO, V4.0 Hor. ResolutionΔx=2.8 km # vert. layer50 Initial/bd. Data COSMO-EU Analysis Model start07 UTC Shallow Convection mod. Tiedke- Scheme TurbulenceTKE-Scheme MicrophysicsGraupel-Scheme Tur_len500 Radiation calc. every time step COSMO model simulations Reference ECMWF initial/boundary conditions reduced turbulent mixing length reduced soil moisture Enhanced soild moisture Start of simulation at 12 UTC On 15 July 2007 a single convective cell formed in the COPS area at about 1440 UTC. The initiation of this cell occurred on the eastern side of the Kinzig Valley in the region with shallow cloud covers in the early afternoon. The maximum amount of surface precipitation derived from the gauge-adjusted radar observations is 11.7 mm. Gauge-adjusted surface precipitation derived from radar, DWD RW product, between 9 and 19 UTC. Radar observations from IMK radar, 1440 UTC High-resolution MSG image, 1442 UTC Case Study, 15 July 2007, IOP 8b Vertical distribution of water vapour COSMO-DE Analysis COSMO-IPA 50 o N 48.5 o N 50 o N 48.5 o N Include GPS, Analysis data, COSMO model, also add some cross section through the Rhine valley, maybe compare with LIDAR obs. Spatial distribution of water vapour GPS derived water vapour, 14 UTCCOSMO-DE Analysis, 14 UTC COSMO-IPA, 14 UTC COSMO-IPA (ECMWF), 14 UTC GPS data kindly provided by GFZ Potsdam, Dr. Galina Dick The model simulations represent well the atmospheric conditions in the morning. This points to the high quality of the initial conditions. Boundary Layer Profiles Achern, 08 UTC Morning: Afternoon: The thickness of the well mixed boundary layer is less than 1 km. The model decently reproduces the temperature and tends to underestimates the moisture. The MESO-NH model was able to predict the convective precipitation. The boundary layer moisture is well reproduced, while the temperature is underestimated. Burnhaupt, 08 UTC MESO-NH data kindly provided by Evelyne Richard