The field experiment BASIS 1998 took place in the Gulf of Bothnia in the Baltic Sea in a boundary zone between the open sea and the ice-covered sea from 16 February to 7 March, 1998. BASIS 1998 as well as the field experiments BASIS 2001 and ALKOR 2000 and 2001 are part of the research compound BALTIMOS (BALTic sea Integrated MOdel System). BALTIMOS in turn is part of the Baltic Sea Experiment (BALTEX).

The overall objective of all eight field experiments (ALKOR and BASIS) was to collect a comprehensive data set suited to validate the coupled model system BALTIMOS for the Baltic Sea region. The observations mainly focus on:

- the atmospheric boundary layer structure and processes and the air-sea-ice interaction over areas with inhomogeneous sea ice cover

- the atmospheric boundary layer structure over open water under different synoptic conditions such as cold-air advection, warm-air advection or frontal passages.

Observations during BASIS 2001 were made at three land stations and the Finnish research vessel Aranda. All stations performed radiosonde measurements. The German research aircraft Falcon had six flight missions with measurements of meteorological parameters and turbulent fluxes.

In addition to the published datasets several other measurements were performed during the experiment. Corresonding datasets will be published in the near future and are available on request.

Details about all used platforms and sensors and all performed measurements are listed in the fieldreport.

The following datasets are available on request: meteorological stations Kokkola, Umea, Merikarvia, ground data at RV Aranda