ICE Synthetic Aperture Radar (ICESAR)
Winter Radiation and Turbulence Interaction Study (ARTIST)
Radiation and Eddy Flux Experiment (REFLEX)
In the research project ARTIST scientists from 7 institutions in 3 European countries studied processes of the energy transfer between the ocean and the atmosphere in the Arctic. The project was conducted from 1998 to 2000 with a major field campaign involving aircraft, surface and satellite measurements in the spring of 1998.
The project was supported by funds of the participating institutions and of the programme ``Environment and Climate'' of the European Commission. Artist was conducted during the years 1998 to 2000 with a cooperative field experiment in March and April 1998.
The project addressed the effects of clouds and of Arctic Haze on the radiative fluxes at the surface and in the atmospheric column for various states of the surface in the European Arctic. Major emphasis was put on convective clouds over the ice-free ocean and on stratiform clouds at low levels and their radiational exchange with sea ice.
The effects of clouds on the radiative fluxes for various states of the ocean surface were studied by (a) detailed aircraft measurements, with vertical profiles of temperature, humidity, up- and downwelling radiative fluxes, particle size distributions in clouds and aerosol optical thickness and (b) ground based measurements at a meteorological station in Svalbard with radiation sensors and a rawinsonde equipment. Radiation schemes for atmospheric and sea ice models have been tested and improved by the use of the data.
Parametrizations of the air-sea exchange of heat, momentum and water vapour and of the turbulent fluxes in the Arctic boundary layer have been obtained by aircraft measurements and numerical modelling. The turbulent energy and momentum fluxes were determined directly with aircraft gust probe instruments. The surface temperature was very inhomogeneous for oceans with partial ice cover and classical boundary layer schemes cannot describe area averages of the turbulent exchange adequately.
Two- and three-dimensional mesoscale models are used in studying the thermodynamics and dynamics of the cloudy boundary layer over the ice-covered ocean in the Arctic. They are run with initial and boundary conditions obtained from the measurements and verified by comparison with field data. Aircraft operations have been synchronized with the overpasses of suitable satellites like the ERS-2 and NOAA-satellites. Cloud and sea ice information was obtained from the satellite remote sensing data with standard algorithms and compared with the in-situ-data to achieve algorithm improvements. Surface data are obtained during flights below clouds, which mask the surface and made verification studies of this kind difficult in the past.