Common experiments have been carried out in a maritime environment under the Swedish-Netherlands Memorandum of Understanding. The implementing arrangement was entitled "IR detection of nearhorizon maritime targets" and the objectives of the measurements were to collect data for the study of atmospheric refraction effects and scintillation. Other objectives were to collect IR-background data and data from near-horizon clutter sources. The experiments were carried out at Landsort south of Stockholm with sources for refraction measurements on Nåttarö. Sweden was responsible for two measurements: Optical wave propagation measurements over an 18.6 km optical path. Spectral IR-background measurements. This report covers the results from the Swedish measurements. Results are presented and some conclusions are made. The data from the wave propagation measurements have been analysed and relevant values such as beam deviation and diameter of blur circle have been calculated. Both these parameters were found to be correlated to the ASTD (Air to Sea Temperature Difference). A comparison was made with results from the wave propagation code IRBLEM. For the beam deviation the agreement was good, but for the beam diameter the agreement varied with the ASTD. The report also shows examples of calibrated IR radiance spectra from different background objects. Special interest has been paid to the sky background and the sea surface.