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Infos on Prudence

Infos on Prudence. Nested regional model ensemble Global model (at least for the 2 models we present): HadAM3H CTL and A2 (other scenarios and global models were used too), Auflösung 1.875x1.25 10 verschiedene Regionalmodelle, inkl einiger Varianten, Auflösung 0.5x0.5 Grad

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Infos on Prudence

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  1. Infos on Prudence • Nested regional model ensemble • Global model (at least for the 2 models we present): HadAM3H CTL and A2 (other scenarios and global models were used too), Auflösung 1.875x1.25 • 10 verschiedene Regionalmodelle, inkl einiger Varianten, Auflösung 0.5x0.5 Grad • Windvalidierungen (10m wind und gust) der Regionalmodelle: Burkhardt Rockel, GKSS (naechste 2 Folien). a) model gusts gegen Stationsmessungen, und b) CTL 10m-wind 99% Quantile und Means

  2. Burkhardt Rockel, GKSS obs

  3. Nur GKSS und ETHZ brauchbar, bessere gust-parametrisierung und TKE Schema (?) • (b) CHRM • The limited area model CHRM derives from the operational weather forecasting model HRM of the German and Swiss meteorological services (Majewski 1991), which has been adapted into a climate version by ETH Zürich (Lüthi et al. 1996, Vidale et al. 2002). The model's computational grid is a regular latitude/longitude grid (81x91 grid points) with a rotated pole, a resolution of 0.5° (about 55 km) and 20 vertical levels in hybrid coordinates. The model has a full package of physical parameterizations, including a mass-flux scheme for moist convection (Tiedtke 1989) and a Kessler-type microphysics (Kessler 1969, Lin et al. 1983). The lateral boundaries are updated every six hours (with linear interpolation in between), while the soil state is only initialized. A detailed description of the actual model version and further evaluations are given in Vidale et al. (2002). CHRM and REMO (see below) share the same dynamical core, but they differ in terms of physical parameterizations.

  4. (h) CLM: • The Climate version of the Lokalmodell (CLM) has the same dynamic and physical core as the weather forecast model LM (Lokalmodell) of the German Weather Service (DWD) (Steppeler et al. 2003, and http://cosmo-model.cscs.ch/cosmoPublic/frame.htm). • The CLM is non-hydrostatic and fully elastic. Calculations are performed on a rotated spherical Arakawa C-grid in horizontal direction, and on hybrid terrain-following coordinates in the vertical. The integration in time follows a horizontally explicit and vertically implicit time-splitting scheme. Lateral boundary formulation in grid space is due to Davis (1976). Optionally a boundary formulation in spectral space (called spectral nudging) can be used (von Storch, 2000). A fourth-order linear horizontal diffusion and a Rayleigh-damping in upper layers is part of the model. • Grid scale precipitation is considered including parameterized cloud microphysics (water and ice). Moist convection is parameterized by the mass flux convection scheme after Tiedtke (1989) modified by using a CAPE-closure. A level 2.5 vertical diffusion scheme is implemented including a laminar boundary layer. The delta-two-stream radiation scheme is after Ritter and Geleyn (1992) for short- and longwave fluxes with full cloud-radiation feedback. Soil temperature and water/ice are calculated by a multi-layer soil model. The soil temperature is predicted by a direct solution of the heat conduction equation. A prognostic TKE (turbulent energy) 2.5 level closure scheme can optionally be switch on. • For the requested simulations within PRUDENCE the CLM is run on a rotated spherical grid with a grid mesh of 0.5 degrees (i.e. approx. 56 km) and a total of 101x107 grid points. In a boundary zone of about 8 grid points the influence of the driving model is significant. The vertical height coordinates are hybrid terrain-following height on 20 levels. The multi-layer soil model is run with 9 soil layers (deepest layer at approx. 15m). Deep soil temperature is set to annual mean temperature from the CRU data set. Prognostic cloud ice parameterization and prognostic TKE scheme are switched on for Simulations CTRL and SA2. • The data sets in the PRUDENCE archive with the acronyms CTRL and SA2 were performed with two optional parameterizations switched on: a prognostic ice cloud parameterization and a prognostic TKE scheme. As it turned out the prognostic ice scheme is very sensitive to the driving model. In contrary to experiences at the DWD (were the LM is driven by their own global model which contains basically the same physics as the LM) the CLM produced too high precipitation amount when driven by the Hadley Centre AGCM. For CTRL and SA2 spectral nudging is not applied.

  5. OUR STRATEGY Chosen criterion at every land grid point: v/v98 > 1.3 (all winter days: October-March) for at least 3 gridpoints Minimum windspeed has to exceed 15m/s (loss model cut-off) Applied to ERA40 to test criteria on identification of real storms Many tests with thresholds, pdfs and all models Select wind events (days), generate wind fields and remap to new grid (SwissRe), apply loss model Probabilistic sets Calibration issues/tests (SSI, return periods, wind pdfs) Now used: calibration to total loss in CTL vs SwissRe set Apply criteria to A2 and work out change in storm loss

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