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- ItemRegional climate model simulations as input for hydrological applications: Evaluation of uncertainties(München : European Geopyhsical Union, 2005) Kotlarski, S.; Block, A.; Böhm, U.; Jacob, D.; Keuler, K.; Knoche, R.; Rechid, D.; Walter, A.The ERA15 Reanalysis (1979-1993) has been dynamically downscaled over Central Europe using 4 different regional climate models. The regional simulations were analysed with respect to 2m temperature and total precipitation, the main input parameters for hydrological applications. Model results were validated against three reference data sets (ERA15, CRU, DWD) and uncertainty ranges were derived. For mean annual 2 m temperature over Germany, the simulation bias lies between -1.1°C and +0.9°C depending on the combination of model and reference data set. The bias of mean annual precipitation varies between -31 and +108 mm/year. Differences between RCM results are of the same magnitude as differences between the reference data sets.
- ItemReliability of regional climate model simulations of extremes and of long-term climate(Göttingen : Copernicus GmbH, 2004) Böhm, U.; Kücken, M.; Hauffe, D.; Gerstengarbe, E.-W.; Werner, P.C.; Flechsig, M.; Keuler, K.; Block, A.; Ahrens, W.; Nocke, T.We present two case studies that demonstrate how a common evaluation methodology can be used to assess the reliability of regional climate model simulations from different fields of research. In Case I, we focused on the agricultural yield loss risk for maize in Northeastern Brazil during a drought linked to an El-Niño event. In Case II, the present-day regional climatic conditions in Europe for a 10-year period are simulated. To comprehensively evaluate the model results for both kinds of investigations, we developed a general methodology. On its basis, we elaborated and implemented modules to assess the quality of model results using both advanced visualization techniques and statistical algorithms. Besides univariate approaches for individual near-surface parameters, we used multivariate statistics to investigate multiple near-surface parameters of interest together. For the latter case, we defined generalized quality measures to quantify the model's accuracy. Furthermore, we elaborated a diagnosis tool applicable for atmospheric variables to assess the model's accuracy in representing the physical processes above the surface under various aspects. By means of this evaluation approach, it could be demonstrated in Case Study I that the accuracy of the applied regional climate model resides at the same level as that we found for another regional model and a global model. Excessive precipitation during the rainy season in coastal regions could be identified as a major contribution leading to this result. In Case Study II, we also identified the accuracy of the investigated mean characteristics for near-surface temperature and precipitation to be comparable to another regional model. In this case, an artificial modulation of the used initial and boundary data during preprocessing could be identified as the major source of error in the simulation. Altogether, the achieved results for the presented investigations indicate the potential of our methodology to be applied as a common test bed to different fields of research in regional climate modeling.
- ItemEvaluation of water balance components in the Elbe river catchment simulated by the regional climate model CCLM(Stuttgart : Gebrueder Borntraeger Verlagsbuchhandlung, 2014) Volkholz, J.; Grossman-Clarke, S.; Hattermann, F.F.; Böhm, U.For investigations of feedbacks between the hydrological cycle and the climate system, we assess the performance of the regional climate model CCLM in reconstructing the water balance of the Elbe river catchment. To this end long-term mean precipitation, evapotranspiration and runoff are evaluated. Extremes (90th percentile) are also considered in the case of precipitation. The data are provided by a CCLM presentday simulation for Europe that was driven by large-scale global reanalyses. The quality of the model results is analyzed with respect to suitable reference data for the period 1970 to 1999. The principal components of the hydrological cycle and their seasonal variations were captured well. Basin accumulated, averaged daily precipitation, evapotranspiration and runoff differ by no more than 10% from observations. Larger deviations occur mainly in summer, and at specific areas.
- ItemWasserverfügbarkeit sowie ökologische, klimatische und sozioökonomische Wechselwirkungen im semiariden Nordosten Brasiliens am Beispiel der Bundesstaaten Piauí und Ceará : Fachbereich: Klimaanalyse/ -modellierung - großskaliges hydrologisches Modell ; Teilprojekt: Klimaanalyse/ -modellierung ; Vorhabensbezeichnung: Analyse und Modellierung der raumzeitlichen klimatischen Bedingungen im Nordosten Brasiliens zur Entwicklung von Klimaszenarien im Verbundprojekt WAVES - Water Availability, Vulnerability of Ecosystems and Society in the Northeast of Brazil ; Abschlussbericht(Hannover : Technische Informationsbibliothek (TIB), 2002) Gerstengarbe, Friedrich-Wilhelm; Werner, P.C.; Böhm, U.; Kücken, M.; Hauffe, D.[no abstract available]
- ItemSimulation von Extremereignissen mit dem regionalen Klimamodell CLM : Schlussbericht ; Projektlaufzeit: 01.01.2009 bis 31.12.2011(Hannover : Technische Informationsbibliothek (TIB), 2012) Gerstengarbe, F.-W.; Böhm, U.; Grossmann, S.; Österle, H.; Kücken, M.; Volkholz, J.; Werner, P.C.; Werner, U.; Wodinski, M.[no abstract available]