PIs: Kerstin Ebell, Marion Maturilli, Justus Notholt

The overarching goal of this project is to characterize the thermodynamic structure, clouds, aerosols, trace gases and radiative effects in the atmospheric column on a long–term basis at the German/Frenchresearch site in Ny–Ålesund/Svalbard, exploiting the synergy of various remote sensing instruments (CONCORD: Continuous characterization of the Ny–Ålesund column and radiative effects from ground–based remote sensing). Thereby, the Ny–Ålesund column will become a valuable piece of the puzzle in the determination of Arctic climatologies from ground–based observations. The data will be used in various ways: for model evaluation and improvement (D01, D02, E01, E03, E04, B05), as a reference for satellite and airborne retrieval algorithms (B01, B02, B03, C01), and to complement in–situ experiments (A02, B03, B06). In order to achieve the long–term column characterization, we will make use of the established routine observations at the research station in Ny–Ålesund as well as from new observation methods and instrumentation that will be installed within (AC)³. Quality and consistency checks will be applied to the measurements in order to provide a comprehensive data set of the various instruments and their uncertainties. On the basis of this high–quality observational data, vertical profiles of the thermodynamic state, clouds, aerosols and trace gas concentrations will be retrieved using integrated profiling approaches. The comprehensive characterization of the Ny–Ålesund column allows then for the analysis of the radiative impact of clouds, aerosols, trace gases (including water vapour and ozone), as well as its variability and accuracy, which is limited by the accuracy of the retrieved atmospheric properties. Finally, the long–term column characteristics at Ny–Ålesund and its variability will be connected to the large–scale and local meteorology. In the context of observations at other Arctic sites (supersites, ship–based and airborne campaigns; A01, B03, B06), the representativeness of the Ny–Ålesund site will be analysed: Climatologically, Ny–Ålesund is located in the warmest part of the Arctic where relatively high tropospheric temperatures are maintained by diabatic heating from the warm ocean.

In order to test the hypothesis, we will address the following central questions:

• To what extent and with which accuracy can we gain insight into the thermodynamic, trace gas, aerosol and cloud macro– and microphysical properties at Ny–Ålesund?
• What is their impact on the radiation and energy budget throughout the vertical extent from the surface to the lower mesosphere?

• How representative are the Ny–Ålesund observations across other Arctic sites?

CONCORD obeservations and retrievals

• as benchmark for model evaluation (B05, D01, D02, E01, E03, E04)

• as reference and validation data set for satellite and airborne retrieval algorithms (B01, B02, B03, B06)
• as complement and tie campaign experiments (A01, A02, B03, B06)