Auflistung nach Autor:in "Karstens, Ute"

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  • Vorschaubild
    Publikation
    The regional aerosol-climate model REMO-HAM
    (Copernicus, 01.11.2012) Pietikäinen, Joni-Pekka; O'Donnell, Denis; Teichmann, Christopher; Karstens, Ute; Pfeifer, Samuel; Kazil, Jan; Podzun, Ralf; Fiedler, Susann; Kokkola, Harri; Birmili, Wolfram; O'Dowd, Colin D.; Baltensperger, Urs; Weingartner, Ernest; Gehrig, Robert; Spindler, Gerald; Kulmala, Markku; Feichter, Johann; Jacob, Daniela; Laaksonen, Aatto [in: Geoscientific Model Development]
    REMO-HAM is a new regional aerosol-climate model. It is based on the REMO regional climate model and includes most of the major aerosol processes. The structure for aerosol is similar to the global aerosol-climate model ECHAM5-HAM, for example the aerosol module HAM is coupled with a two-moment stratiform cloud scheme. On the other hand, REMO-HAM does not include an online coupled aerosol-radiation nor a secondary organic aerosol module. In this work, we evaluate the model and compare the results against ECHAM5-HAM and measurements. Four different measurement sites were chosen for the comparison of total number concentrations, size distributions and gas phase sulfur dioxide concentrations: Hyytiälä in Finland, Melpitz in Germany, Mace Head in Ireland and Jungfraujoch in Switzerland. REMO-HAM is run with two different resolutions: 50 × 50 km2 and 10 × 10 km2. Based on our simulations, REMO-HAM is in reasonable agreement with the measured values. The differences in the total number concentrations between REMO-HAM and ECHAM5-HAM can be mainly explained by the difference in the nucleation mode. Since we did not use activation nor kinetic nucleation for the boundary layer, the total number concentrations are somewhat underestimated. From the meteorological point of view, REMO-HAM represents the precipitation fields and 2 m temperature profile very well compared to measurement. Overall, we show that REMO-HAM is a functional aerosol-climate model, which will be used in further studies.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Transport of 222Rn using the regional model REMO. a detailed comparison with measurements over Europe
    (Stockholm University Press, 2002) Chevillard, Anne; Ciais, Philippe; Karstens, Ute; Heimann, Martin; Schmidt, Martina; Levin, Ingeborg; Jacob, Daniela; Podzun, Ralf; Kazan, Victor; Sartorius, Hartmut; Weingartner, Ernest [in: Tellus B: Chemical and Physical Meteorology]
    The 222Rn concentration simulated by the regional atmospheric model REMO over Europe and western Siberia is compared to in-situ records in Europe, and discussed in the context of site effects for stations that are also part of a CO2 observing network. The REMO model has a limited spatial domain, forced at its lateral boundaries with meteorological fields of the European Centre for Medium-Range Weather Forecasts and with tracer concentrations issued from the TM3 global transport model. The modelled 222Rn field is compared to measurements at six stations: two coastal ones (Atlantic Ocean and Baltic Sea), two low-elevation sites in plains, one mountain station and one high-altitude station. We show that the synoptic and diurnal 222Rn variability as simulated by REMO (55 km by 55 km) is realistic. In some cases REMO performs better than TM3, which is of coarser resolution, but this is not always true. At Mace Head, a station located near the western edge of the REMO domain, we show that the 222Rn “baseline” concentration is strongly influenced by boundary conditions, reflecting 222Rn transport from North America across the Atlantic Ocean. At Schauinsland, a mountain station in south western Germany, even though the spatial resolution of REMO is not fine enough to reproduce transport processes induced by local topography, a fairly good agreement between model and measurements can be obtained, provided that one can determine from comparison of observed and modelled diurnal temperature changes which layer of the model is suitable for comparison with the data. Finally, the implications of modelling 222Rn are discussed here in the broader context of interpreting site effects that may also affect CO2 continental observations in Europe.
    01A - Beitrag in wissenschaftlicher Zeitschrift