Climatic variability in the Skagerrak and coastal waters of Norway

Abstract

The Institute of Marine Research in Norway collects marine data from all national waters. Data are primarily collected from vessels, but observation buoys, manual measurements, and oceanographic gliders are also used. The most valuable long-term data for elucidating decadal hydrographic variability in the Skagerrak and along the Norwegian coast are the time-series from the transect between Norway and Denmark, and observations carried out at eight fixed coastal stations in the region. The time-series date back to the 1950s and the 1930s, respectively, and the observation frequencies range from approximately once a month to 3–4 times per month. The hydrographic data and their long-term fluctuations have been used in several studies, with particular emphasis on the increased salinity and temperature of the 1990s. Trends during the past decade, however, indicate that warming has continued but that a salinity increase is less evident, implying signs of regional warming in parallel with the global warming observed both on land and in the sea. The overall temperature increase off the Norwegian coast at deeper layers from the 1961–1990 period to the 2000–2009 decade is ~0.8°C, but some of this can be related to natural variability in the North Atlantic circulation pattern.