Current and temperature measurments with moored instruments in the Norwegian Current showed considerable fluctuations with periods of 2--3 days. An analytical model calculation (Mysak and Schott, 1977) suggested that these current fluctuations are most likely due to baroclinic instability of the mean flow. For current and temperature measurements from a cross of moorings, and from ship section data, vertical profiles of the barotropic and baroclinic instability terms are calculated. It is found that at the position of the mooring cross, energy is transferred into the pertubations by baroclinic instability, but that the barotropic terms transfer energy from the pertubations into the mean flow at a larger rate. The wavelengths of the fluctuations, calculated by high-resolution directional spectra, are in the range of 30--40 km, in agreement with the analytical model results.