Das Projekt "ARTIST: Studie zur Wechselwirkung von Strahlung und Turbulenz (ARTIST)" wird vom Umweltbundesamt gefördert und von GKSS-Forschungszentrum Geesthacht, Institut für Atmosphärenphysik durchgeführt. The ARTIST programme aims to improve the understanding and formal description of the radiative and thermodynamic interaction between Arctic clouds and sea-ice. For this purpose the energy fluxes within the atmosphere and at the surface of the polar ocean as well as the cloud physical properties will be investigated by direct field measurements, aircraft and satellite remote sensing and by numerical modelling. ARTIST will assess the effects of clouds and Arctic Haze on the radiative fluxes at the sea surface and within the atmospheric column for various atmospheric states and different lower boundary conditions. Major emphasis will be put on studies of stratiform clouds at low levels, their time and space variability and their radiation interaction with the sea ice. Improvement of actual radiation schemes are expected to be obtained from detailed considerations of the cloud optical thickness, liquid and solid water content as well as the particle size distributions in clouds. Furthermore the parametrisations of the air-sea exchanges of heat, momentum and water vapour and of the vertical turbulent fluxes within the Arctic boundary layer will be improved by measurements and model experiments. For the latter the ARTIST data will provide initial and boundary conditions and they will also serve to validate experiments by which the thermodynamics and dynamics of the cloudy boundary layer over the ice-covered ocean are studied. Measurements will be synchronized with the overpasses of suitable satellites as much as possible to test and to improve retrieval algorithms of sea surface and atmospheric properties for passive and active microwave as well as for visible and infrared channels.
Das Projekt "Fine Structure of the Stably Stratified Atmospheric Boundary Layer in Antarctica" wird vom Umweltbundesamt gefördert und von Technische Universität Braunschweig, Institut für Luft- und Raumfahrtsysteme durchgeführt. As element of the cooperation between the Inst. f. Luft- und Raumfahrtsysteme, Techn. Univ. Braunschweig (ILR), and the British Antarctic Survey (HAS) in total three small meteorological flight robots (M2AV) are sent to Halley station. There the fully autonomously operating aircraft (developed at the ILR) are going to measure the turbulent characteristics of the stable atmospheric boundary layer (SBL) above the ice shelf. These in situ measurements are then used to verify, support and complete the already installed BAS sodar systems and the meteorological tower. Main research goal is the fine structure of the SBL especially regarding thin layers, intermittent and fossil turbulence, and (solitary) waves. The use of structure functions, multi-resolution co-spectra and wavelet analysis give information on the spectral characteristics of turbulent structure and transport within the layered SBL. Applying inverse models to the observed data, gradients, divergence and energy fluxes are calculated in order to quantify the turbulent energy transfer between SBL and surface, and between individual layers. Furthermore the horizontal representativeness of the installed remote sensing systems is validated. In the preceding project PSBL a large quality-controlled database from Helipod flights over Arctic sea ice (Polarstern campaigns ARK-XI, ARK-XII and ARK-XIX) was already created. This data base is now used to analyse the resemblance and difference between the SBL over shelf ice (Antarctic) and sea ice (Arctic). The project will contribute to the understanding of specific elements and processes of the SBL particularly under polar conditions. At the beginning of the project all experiments and journals will be already completed. Thus we apply only for man power to analyse the unique data sets from Halley station and M2AVs.
Das Projekt "North Atlantic Climate: Predictability of the climate in the North Atlantic/European sector related to North Atlantic/Arctic sea surface temperature and sea ice variability and change (NACLIM)" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Fakultät für Mathematik, Informatik und Naturwissenschaften, Team 452.1: EU-Projekte durchgeführt. Objective: NACLIM aims at investigating and quantifying the predictability of the climate in the North Atlantic/European sector related to North Atlantic/Arctic sea surface temperature (SST) and sea ice variability and change on seasonal to decadal time scales. SST and sea-ice forcing have a crucial impact on weather and climate in Europe. Rather than running climate forecasts ourselves, we will analyse the multi-model decadal prediction experiments currently performed as part of the fifth Coupled Model Intercomparison Project (CMIP5) and critically assess the quality of predictions of the near-future state of key oceanic and atmospheric quantities relevant to the SST and sea-ice distribution and the related climate. Long-term observations of relevant ocean parameters will be carried out, necessary to assess the forecast skill of the model-based prediction results. We will identify those observations that are key to the quality of the prediction and in turn optimize the present observing system. We will quantify the impact of North Atlantic/European climate change on high trophic levels of the oceanic ecosystem as well as on urban societies.