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  • 1
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    Large‐eddy simulations over Germany using ICON: a comprehensive evaluation
    Wiley ; 2017
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 143, No. 702 ( 2017-01), p. 69-100
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 143, No. 702 ( 2017-01), p. 69-100
    Abstract: Large‐eddy simulations (LES) with the new ICOsahedral Non‐hydrostatic atmosphere model (ICON) covering Germany are evaluated for four days in spring 2013 using observational data from various sources. Reference simulations with the established Consortium for Small‐scale Modelling (COSMO) numerical weather prediction model and further standard LES codes are performed and used as a reference. This comprehensive evaluation approach covers multiple parameters and scales, focusing on boundary‐layer variables, clouds and precipitation. The evaluation points to the need to work on parametrizations influencing the surface energy balance, and possibly on ice cloud microphysics. The central purpose for the development and application of ICON in the LES configuration is the use of simulation results to improve the understanding of moist processes, as well as their parametrization in climate models. The evaluation thus aims at building confidence in the model's ability to simulate small‐ to mesoscale variability in turbulence, clouds and precipitation. The results are encouraging: the high‐resolution model matches the observed variability much better at small‐ to mesoscales than the coarser resolved reference model. In its highest grid resolution, the simulated turbulence profiles are realistic and column water vapour matches the observed temporal variability at short time‐scales. Despite being somewhat too large and too frequent, small cumulus clouds are well represented in comparison with satellite data, as is the shape of the cloud size spectrum. Variability of cloud water matches the satellite observations much better in ICON than in the reference model. In this sense, it is concluded that the model is fit for the purpose of using its output for parametrization development, despite the potential to improve further some important aspects of processes that are also parametrized in the high‐resolution model.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.2017.143.issue-702
    DOI: 10.1002/qj.2947
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2017
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  • 2
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    The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe
    Copernicus GmbH ; 2018
    In:  Atmospheric Chemistry and Physics Vol. 18, No. 23 ( 2018-12-11), p. 17545-17572
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 23 ( 2018-12-11), p. 17545-17572
    Abstract: Abstract. A regional modeling study on the impact of desert dust on cloud formation is presented for a major Saharan dust outbreak over Europe from 2 to 5 April 2014. The dust event coincided with an extensive and dense cirrus cloud layer, suggesting an influence of dust on atmospheric ice nucleation. Using interactive simulation with the regional dust model COSMO-MUSCAT, we investigate cloud and precipitation representation in the model and test the sensitivity of cloud parameters to dust–cloud and dust–radiation interactions of the simulated dust plume. We evaluate model results with ground-based and spaceborne remote sensing measurements of aerosol and cloud properties, as well as the in situ measurements obtained during the ML-CIRRUS aircraft campaign. A run of the model with single-moment bulk microphysics without online dust feedback considerably underestimated cirrus cloud cover over Germany in the comparison with infrared satellite imagery. This was also reflected in simulated upper-tropospheric ice water content (IWC), which accounted for only 20 % of the observed values. The interactive dust simulation with COSMO-MUSCAT, including a two-moment bulk microphysics scheme and dust–cloud as well as dust–radiation feedback, in contrast, led to significant improvements. The modeled cirrus cloud cover and IWC were by at least a factor of 2 higher in the relevant altitudes compared to the noninteractive model run. We attributed these improvements mainly to enhanced deposition freezing in response to the high mineral dust concentrations. This was corroborated further in a significant decrease in ice particle radii towards more realistic values, compared to in situ measurements from the ML-CIRRUS aircraft campaign. By testing different empirical ice nucleation parameterizations, we further demonstrate that remaining uncertainties in the ice-nucleating properties of mineral dust affect the model performance at least as significantly as including the online representation of the mineral dust distribution. Dust–radiation interactions played a secondary role for cirrus cloud formation, but contributed to a more realistic representation of precipitation by suppressing moist convection in southern Germany. In addition, a too-low specific humidity in the 7 to 10 km altitude range in the boundary conditions was identified as one of the main reasons for misrepresentation of cirrus clouds in this model study.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    DOI: 10.5194/acp-18-17545-2018
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
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  • 3
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    Detection and attribution of aerosol–cloud interactions in large-domain large-eddy simulations with the ICOsahedral Non-hydrostatic model
    Copernicus GmbH ; 2020
    In:  Atmospheric Chemistry and Physics Vol. 20, No. 9 ( 2020-05-13), p. 5657-5678
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 20, No. 9 ( 2020-05-13), p. 5657-5678
    Abstract: Abstract. Clouds and aerosols contribute the largest uncertainty to current estimates and interpretations of the Earth’s changing energy budget. Here we use a new-generation large-domain large-eddy model, ICON-LEM (ICOsahedral Non-hydrostatic Large Eddy Model), to simulate the response of clouds to realistic anthropogenic perturbations in aerosols serving as cloud condensation nuclei (CCN). The novelty compared to previous studies is that (i) the LEM is run in weather prediction mode and with fully interactive land surface over a large domain and (ii) a large range of data from various sources are used for the detection and attribution. The aerosol perturbation was chosen as peak-aerosol conditions over Europe in 1985, with more than fivefold more sulfate than in 2013. Observational data from various satellite and ground-based remote sensing instruments are used, aiming at the detection and attribution of this response. The simulation was run for a selected day (2 May 2013) in which a large variety of cloud regimes was present over the selected domain of central Europe. It is first demonstrated that the aerosol fields used in the model are consistent with corresponding satellite aerosol optical depth retrievals for both 1985 (perturbed) and 2013 (reference) conditions. In comparison to retrievals from ground-based lidar for 2013, CCN profiles for the reference conditions were consistent with the observations, while the ones for the 1985 conditions were not. Similarly, the detection and attribution process was successful for droplet number concentrations: the ones simulated for the 2013 conditions were consistent with satellite as well as new ground-based lidar retrievals, while the ones for the 1985 conditions were outside the observational range. For other cloud quantities, including cloud fraction, liquid water path, cloud base altitude and cloud lifetime, the aerosol response was small compared to their natural variability. Also, large uncertainties in satellite and ground-based observations make the detection and attribution difficult for these quantities. An exception to this is the fact that at a large liquid water path value (LWP 〉 200 g m−2), the control simulation matches the observations, while the perturbed one shows an LWP which is too large. The model simulations allowed for quantifying the radiative forcing due to aerosol–cloud interactions, as well as the adjustments to this forcing. The latter were small compared to the variability and showed overall a small positive radiative effect. The overall effective radiative forcing (ERF) due to aerosol–cloud interactions (ERFaci) in the simulation was dominated thus by the Twomey effect and yielded for this day, region and aerosol perturbation −2.6 W m−2. Using general circulation models to scale this to a global-mean present-day vs. pre-industrial ERFaci yields a global ERFaci of −0.8 W m−2.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    DOI: 10.5194/acp-20-5657-2020
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
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  • 4
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    EARLINET correlative measurements for CALIPSO: First intercomparison results
    American Geophysical Union (AGU) ; 2010
    In:  Journal of Geophysical Research Vol. 115 ( 2010-04-15)
    Details
    In: Journal of Geophysical Research, American Geophysical Union (AGU), Vol. 115 ( 2010-04-15)
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2009JD012147
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2010
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  • 5
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    Seasonal variability of heterogeneous ice formation in stratiform clouds over the Amazon Basin
    American Geophysical Union (AGU) ; 2015
    In:  Geophysical Research Letters Vol. 42, No. 13 ( 2015-07-16), p. 5587-5593
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 42, No. 13 ( 2015-07-16), p. 5587-5593
    Abstract: A unique 1 year stratiform cloud data set was obtained for the Amazon Basin During the dry season, ice forms more efficient than during the wet season Biomass burning aerosols must be the source of ice nuclei during the dry season
    Type of Medium: Online Resource
    ISSN: 0094-8276 , 1944-8007
    URL: Issue
    URL: Article
    DOI: 10.1002/grl.v42.13
    DOI: 10.1002/2015GL064068
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2015
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  • 6
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    Correction to “Volcanic aerosol layers observed with multiwavelength Raman lidar over central Europe in 2008–2009”
    American Geophysical Union (AGU) ; 2010
    In:  Journal of Geophysical Research: Atmospheres Vol. 115, No. D19 ( 2010-10-16)
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 115, No. D19 ( 2010-10-16)
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2010JD014895
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2010
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    SSG: 16,13
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  • 7
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    Simultaneous Measurement of 2':3' Cyclic-Nucleotide 3' Phosphodiesterase and RNase Activities in Sera and Spinal Fluids of Multiple Sclerosis Patients
    Wiley ; 1984
    In:  Journal of Neurochemistry Vol. 42, No. 1 ( 1984-01), p. 12-15
    Details
    In: Journal of Neurochemistry, Wiley, Vol. 42, No. 1 ( 1984-01), p. 12-15
    Type of Medium: Online Resource
    ISSN: 0022-3042 , 1471-4159
    URL: Issue
    URL: Article
    DOI: 10.1111/jnc.1984.42.issue-1
    DOI: 10.1111/j.1471-4159.1984.tb09690.x
    Language: English
    Publisher: Wiley
    Publication Date: 1984
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  • 8
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    Comparison of Raman Lidar Observations of Water Vapor with COSMO-DE Forecasts during COPS 2007
    American Meteorological Society ; 2011
    In:  Weather and Forecasting Vol. 26, No. 6 ( 2011-12-01), p. 1056-1066
    Details
    In: Weather and Forecasting, American Meteorological Society, Vol. 26, No. 6 ( 2011-12-01), p. 1056-1066
    Abstract: Water vapor measurements with the multiwavelength Raman lidar Backscatter Extinction Lidar-Ratio Temperature Humidity Profiling Apparatus (BERTHA) were performed during the Convective and Orographically-induced Precipitation Study (COPS) in the Black Forest, Germany, from June to August 2007. For quality assurance, profiles of the water vapor mixing ratio measured with BERTHA are compared to simultaneous measurements of a radiosonde and an airborne differential absorption lidar (DIAL) on 31 July 2007. The differences from the radiosonde observations are found to be on average 1.5% and 2.5% in the residual layer and in the free troposphere, respectively. During the two overflights at 1937 and 2018 UTC, the differences from the DIAL results are −2.2% and −3.7% in the residual layer and 2.1% and −2.6% in the free troposphere. After this performance check, short-range forecasts from the German Meteorological Service’s (Deutscher Wetterdienst, DWD) version of the Consortium for Small-Scale Modeling (COSMO-DE) model are compared to the BERTHA measurements for two case studies. Generally, it is found that water vapor mixing ratios from short-range forecasts are on average 7.9% drier than the values measured in the residual layer. In the free troposphere, modeled values are 9.7% drier than the measurements.
    Type of Medium: Online Resource
    ISSN: 0882-8156 , 1520-0434
    URL: Article
    DOI: 10.1175/2011WAF2222448.1
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2011
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  • 9
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    The HD(CP)〈sup〉2〈/sup〉 Observational Prototype Experiment (HOPE) – an overview
    Copernicus GmbH ; 2017
    In:  Atmospheric Chemistry and Physics Vol. 17, No. 7 ( 2017-04-13), p. 4887-4914
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 17, No. 7 ( 2017-04-13), p. 4887-4914
    Abstract: Abstract. The HD(CP)2 Observational Prototype Experiment (HOPE) was performed as a major 2-month field experiment in Jülich, Germany, in April and May 2013, followed by a smaller campaign in Melpitz, Germany, in September 2013. HOPE has been designed to provide an observational dataset for a critical evaluation of the new German community atmospheric icosahedral non-hydrostatic (ICON) model at the scale of the model simulations and further to provide information on land-surface–atmospheric boundary layer exchange, cloud and precipitation processes, as well as sub-grid variability and microphysical properties that are subject to parameterizations. HOPE focuses on the onset of clouds and precipitation in the convective atmospheric boundary layer. This paper summarizes the instrument set-ups, the intensive observation periods, and example results from both campaigns. HOPE-Jülich instrumentation included a radio sounding station, 4 Doppler lidars, 4 Raman lidars (3 of them provide temperature, 3 of them water vapour, and all of them particle backscatter data), 1 water vapour differential absorption lidar, 3 cloud radars, 5 microwave radiometers, 3 rain radars, 6 sky imagers, 99 pyranometers, and 5 sun photometers operated at different sites, some of them in synergy. The HOPE-Melpitz campaign combined ground-based remote sensing of aerosols and clouds with helicopter- and balloon-based in situ observations in the atmospheric column and at the surface. HOPE provided an unprecedented collection of atmospheric dynamical, thermodynamical, and micro- and macrophysical properties of aerosols, clouds, and precipitation with high spatial and temporal resolution within a cube of approximately 10  ×  10  ×  10 km3. HOPE data will significantly contribute to our understanding of boundary layer dynamics and the formation of clouds and precipitation. The datasets have been made available through a dedicated data portal. First applications of HOPE data for model evaluation have shown a general agreement between observed and modelled boundary layer height, turbulence characteristics, and cloud coverage, but they also point to significant differences that deserve further investigations from both the observational and the modelling perspective.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    URL: Article
    DOI: 10.5194/acp-17-4887-2017
    DOI: 10.5194/acp-17-4887-2017-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2017
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  • 10
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    peakTree: a framework for structure-preserving radar Doppler spectra analysis
    Copernicus GmbH ; 2019
    In:  Atmospheric Measurement Techniques Vol. 12, No. 9 ( 2019-09-10), p. 4813-4828
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 12, No. 9 ( 2019-09-10), p. 4813-4828
    Abstract: Abstract. Clouds are frequently composed of more than one particle population even at the smallest scales. Cloud radar observations frequently contain information on multiple particle species in the observation volume when there are distinct peaks in the Doppler spectrum. Multi-peaked situations are not taken into account by established algorithms, which only use moments of the Doppler spectrum. In this study, we propose a new algorithm that recursively represents the subpeaks as nodes in a binary tree. Using this tree data structure to represent the peaks of a Doppler spectrum, it is possible to drop all a priori assumptions on the number and arrangement of subpeaks. The approach is rigid, unambiguous and can provide a basis for advanced analysis methods. The applicability is briefly demonstrated in two case studies, in which the tree structure was used to investigate particle populations in Arctic multilayered mixed-phase clouds, which were observed during the research vessel Polarstern expedition PS106 and the Atmospheric Radiation Measurement Program BAECC campaign.
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    DOI: 10.5194/amt-12-4813-2019
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
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