Optical measurements in the North Sea-Baltic Sea transition zone .2. Water mass classification along the Jutland west coast from salinity and spectral irradiance measurements

Spectral irradiance measurements were gathered along three fixed sections outside Thyboron, Hanstholm and Hirtshals on the north west coast of Denmark during seven cruises with R.V. Svanic in the years 1990-1992. It is argued that the irradiance attenuation coefficient K-d (410) can be taken as a good indicator of yellow substance in the study region. Salinity - K-d(410) scatter plots show that three water types can be identified in the area: Atlantic/Central North Sea water, German Bight water and Baltic water. Estimates of the mean width of the part of the Jutland Coastal Current that primarily is influenced by the freshwater inflow to the German Bight are given for each of the three sections. A salinity - K-d(410) water mass analysis was carried out based on long-term mean characteristic values of salinity and K-d(410) for the three core water types and the measurements from this study. The average contents of Atlantic/Central North Sea water, German Bight water and Baltic water was estimated for the surface layer at each of the three sections. Based on the volume flow estimates (provided as a function of salinity) from the three sections as listed in Rydbeg (Report No. 53, Department of Oceanography, University of Gothenburg, Sweden, 1993) an estimate of the mean volume how of water with German Bight origin entering the Skagerrak is given. (C) 1996 Elsevier Science Ltd