TY - GEN A1 - Böhm, Uwe A1 - Keuler, Klaus A1 - Österle, Hermann A1 - Kücken, Martin A1 - Hauffe, Detlef T1 - Quality of a climate reconstruction for the CADSES regions T2 - Meteorologische Zeitschrift N2 - We used the regional climate model CCLM 4 to reconstruct the climate over the CADSES regions for the period 1961-2000. This most recent model version is currently still in a test phase. The simulation quality for this part of the entire simulation area is exemplarily analyzed by using a small but representative subset of model variables. Mean sea level pressure is chosen as an indicator for the behavior of the near-surface dynamics. Furthermore, the two regional variables 2 m temperature and precipitation are evaluated, which are of relevance for hydrological applications. For additional analyses to identify sources of uncertainty, we used soil moisture and cloudiness. Altogether, the accuracy of the simulation results can be judged as being in good agreement with the results of similar simulations by other regional climate models over Europe. Area-averaged monthly mean 2 m temperatures during winter show a cold bias of about -2 K. The simulated mean sea level pressure is with a bias of about 2 hPa slightly too high compared to the used reference data set. Although cloud cover evaluation hints at insufficiencies in the corresponding parameterization, further analyses are required to unambiguously identify the causes for this cold bias. During summer, higher 2 m temperatures linked to reduced precipitation are identified in nearly identical regions over southern and southeastern Europe. Further analyses of soil moisture evolution and cloud cover give evidence for a source of uncertainty in the surface hydrological scheme. Altogether, the detected differences do not exceed the typical ranges of uncertainty in comparable regional climate simulations over Europe. For input in hydrological applications, however, the uncertainties produced by the CCLM simulation described here have to be reduced in the medium term. N2 - Das Klima über den CADSES-Regionen wurde mit dem regionalen Klimamodell CCLM, Version 4.0 für den Zeitraum 1961-2000 rekonstruiert. Diese aktuellste Modellversion befindet sich gegenwärtig noch in einer Testphase. Die Qualität der Simulation für diesen Teil des Simulationsgebietes wird beispielhaft anhand einer kleinen, aber repräsentativen Teilmenge von Modellvariablen analysiert. Der Druck auf Meeresniveau wurde ausgewählt als Indikator für das Verhalten der bodennahen Dynamik. Weiterhin wurden die beiden Variablen 2 m Temperatur und Niederschlag als wichtige regionale Variablen für hydrologische Anwendungen bewertet. Für zusätzliche Analysen zur Identifizierung von Ungenauigkeitsquellen verwendeten wir die Bodenfeuchte und die Bewölkung. Insgesamt kann die Genauigkeit dieser Simulationsresultate als gut im Vergleich zu Ergebnissen von Simulationsläufen anderer regionaler Klimamodelle für Europa beurteilt werden. Gebietsmittel der monatlichen 2 m Temperaturen im Winter zeigen einen systematischen Fehler von etwa -2 K. Der simulierte Druck auf Meeresniveau ist mit einem systematischen Fehler von etwa 2 hPa etwas zu hoch im Vergleich zum verwendeten Referenzdatensatz. Obwohl die Evaluierung der Wolkendecke auf Unzulänglichkeiten in der entsprechenden Parametrisierung hinweist, sind weitere Analysen nötig, um die Ursachen für das systematisch zu kalte Modellverhalten eindeutig zu identifizieren. Im Sommer treten über nahezu identischen Regionen in Süd- und Südosteuropa höhere 2 m Temperaturen sowie geringere Niederschlägen auf. Weitere Analysen der zeitlichen Entwicklung der Bodenfeuchte und der Wolkenbedeckung geben Anhaltspunkte für eine Quelle von Ungenauigkeit im hydrologischen Teil des Bodenmodells. Insgesamt überschreiten die nachgewiesenen Unterschiede nicht die typischen Fehlerbereiche in vergleichbaren Klimasimulationen über Europa. Als Antrieb für hydrologische Anwendungen ist es allerdings mittelfristig erforderlich, die Ungenauigkeiten der hier beschriebenen CCLM-Simulation zu verringern. Y1 - 2008 U6 - https://doi.org/10.1127/0941-2948/2008/0318 SN - 1610-1227 VL - 17 IS - 4 SP - 477 EP - 485 ER - TY - RPRT A1 - Böhm, Uwe A1 - Kücken, Martin A1 - Ahrens, Wilfried A1 - Block, Alexander A1 - Hauffe, Detlef A1 - Keuler, Klaus A1 - Rockel, Burkhardt A1 - Will, Andreas T1 - CLM - The Climate Version of LM: Brief Description and Long-Term Applications Y1 - 2006 UR - http://www.cosmo-model.org/content/model/documentation/newsLetters/newsLetter06/cnl6_clm.pdf PB - COSMO Newsletter CY - Offenbach, Germany ER - TY - GEN A1 - Böhm, Uwe A1 - Kücken, Martin A1 - Hauffe, Detlef A1 - Gerstengarbe, F.-W. A1 - Werner, P. C. A1 - Flechsig, Michael A1 - Keuler, Klaus A1 - Block, Alexander A1 - Ahrens, Wilfried A1 - Nocke, Th. T1 - Reliability of regional climate model simulations of extremes and of long-term climate T2 - Natural Hazards and Earth System Sciences N2 - 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. Y1 - 2004 U6 - https://doi.org/10.5194/nhess-4-417-2004 VL - 4 IS - 3 SP - 417 EP - 431 ER - TY - GEN A1 - Böhm, Uwe A1 - Kücken, Martin A1 - Ahrens, Wilfried A1 - Block, Alexander A1 - Hauffe, Detlef A1 - Keuler, Klaus A1 - Rockel, Burkhardt A1 - Will, Andreas T1 - The Climate Version of LM: Brief Description and Long-Term Applications T2 - COSMO Newsletter Y1 - 2006 UR - http://www.cosmo-model.org/content/model/documentation/newsLetters/newsLetter06/newsLetter_06.pdf IS - 6 SP - 225 EP - 235 ER -