Czech Hydro Meteorological Institute

Prague, Czech Republic

Czech Hydro Meteorological Institute

Prague, Czech Republic

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Benard P.,Meteo - France | Vivoda J.,Slovak Hydro Meteorological Institute | Mascaronek J.,Slovak Hydro Meteorological Institute | Smolikova P.,Czech Hydro Meteorological Institute | And 5 more authors.
Quarterly Journal of the Royal Meteorological Society | Year: 2010

Drawing from the results of theoretical studies about the behaviour of constant-coefficients semi-Drawing from the results of theoretical studies about the behaviour of constant-coefficients semi-implicit schemes, the dynamical kernel of the Aladin-NH spectral limited-area numerical weather prediction (NWP) model has been modified in order to allow for a stable and efficient integration of the fully elastic Euler equations. The resulting dynamical kernel offers the possibility to use semi-Lagrangian transport schemes together with two-time-level discretizations at kilometric scales for NWP purposes. The main characteristics of the adiabatic part of the model formulation and the space and time discretization are described in this article. In order to illustrate the dependence of the results on adjustable parameters of the dynamical kernel, some real-case dynamical-adaptation forecasts performed with a basic physical parameterization package are presented. The results obtained with this model in real-case experiments fully confirm the conclusions drawn in previous numerical analysis studies. The good quality of the results is found to be compatible with a routine exploitation in a NWP framework. The Aladin-NH dynamical kernel has been used in the operational NWP AROME model since December 2008 at the kilometric scale, with an appropriate physical parameterization package and data assimilation systemDrawing from the results of theoretical studies about the behaviour of constant-coefficients semi-implicit schemes, the dynamical kernel of the Aladin-NH spectral limited-area numerical weather prediction (NWP) model has been modified in order to allow for a stable and efficient integration of the fully elastic Euler equations. The resulting dynamical kernel offers the possibility to use semi-Lagrangian transport schemes together with two-time-level discretizations at kilometric scales for NWP purposes. The main characteristics of the adiabatic part of the model formulation and the space and time discretization are described in this article. In order to illustrate the dependence of the results on adjustable parameters of the dynamical kernel, some real-case dynamical-adaptation forecasts performed with a basic physical parameterization package are presented. The results obtained with this model in real-case experiments fully confirm the conclusions drawn in previous numerical analysis studies. The good quality of the results is found to be compatible with a routine exploitation in a NWP framework. The Aladin-NH dynamical kernel has been used in the operational NWP AROME model since December 2008 at the kilometric scale, with an appropriate physical parameterization package and data assimilation system. © 2010 Royal Meteorological Society and Crown Copyright.


Zacharov P.,Academy of Sciences of the Czech Republic | Rezacova D.,Academy of Sciences of the Czech Republic | Brozkova R.,Czech Hydro Meteorological Institute
Atmospheric Research | Year: 2013

In this paper, quantitative precipitation forecasts (QPF) are evaluated using several verification techniques and analysis of the results from these techniques. The forecasts were produced by two limited-area numerical weather prediction models: the ALADIN-CZ model operated by the Czech Hydro-Meteorological Institute (CHMI) and the COSMO model operated by the German Weather Service (DWD). Each model was run using two horizontal resolutions over the domain covering the Czech Republic. The ALADIN-CZ model outputs were obtained using resolutions of approximately 9. km and 4.7. km, and the COSMO model outputs were obtained using resolutions of approximately 7. km and 2.8. km.The forecast quality is studied for the flash flood period that occurred in June and July of 2009, when convective rainfalls with durations of 1 to 3. h and a return period of more than 100. years caused devastating floods in many Czech localities. The radar-based rainfalls used to verify the forecasts were produced by the CHMI operational product MERGE, which merges radar-derived rainfalls with the rainfalls that are measured by ground rain gauges.A series of 56 consecutive forecasts of 3-h rainfalls were verified using traditional and spatial verification techniques, and the results from these analyses were compared. The verification was performed using traditional verification scores based on a contingency table, spatial verification by the fractions skill score (FSS) and the SAL (structure-amplitude-location) technique. The FSS represents a fuzzy verification technique and compares the fractional coverage of precipitation grids over a threshold in spatial windows around the observations and forecasts. The SAL is a spatial object-oriented verification technique used to evaluate the structure, amplitude, and location of a precipitation field.The quality of QPF depends strongly on the scale of convective precipitation, and all models provide good forecast quality for extended rainfall systems. The opposite is true for the local and more or less chaotic convection during the final part of the time period. The FSS indicates how the results depend on the threshold and scale of precipitation. The COSMO 2.8 model is able to determine the largest local rainfall values, but models with lower resolution, such as the ALADIN 9. km and COSMO 7. km, provide better results for lower thresholds and larger scales. The use of more verification techniques is suitable for a modeller-oriented evaluation of different aspects of forecast quality. © 2013 Elsevier B.V.

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