The field experiment ACSYS 1998 took place in the Greenland Sea west of Spitsbergen from 10 to 25 March 1998. It was planned and organized by scientists of the Meteorological Institute of the University of Hamburg within the national research project ACSYS (Arctic Climate System Study) which was funded by the German Bundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie (BMBF). The national ACSYS project is part of the international ACSYS research program which is a sub-program of the World Climate Research Program (WCRP).

The objective of the ACSYS 1989 field experiment was the investigation of the atmospheric boundary layer in case of on-ice air flow in wintertime. Cyclones, reaching the Arctic sea ice from the Greenland Sea or Barents Sea are the strongest synoptic-scale weather signals in the Arctic region. They transport warm, moist and cloudy air from the open water to the Arctic shield. Especially in wintertime when the temperature contrast between the ocean and the ice surface is large the effects in the boundary layer over the ice are also significant.

The research aircraft Falcon performed six flight missions from 11 to 21 March measuring meteorological parameters and turbulent fluxes.