Fluctuations in the surface temperature and surface salinity of the north‐east Atlantic at frequencies of one cycle per year and below

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Abstract
Time‐series of monthly sea surface temperature and salinity data (1951‐1974) from stations in the N.E. Atlantic were investigated by calculating cross‐spectra using the method of maximum entropy analysis. This new technique has not previously been applied to climatological problems. The temperature and salinity data were also compared with surface heat‐flux and evaporation time‐series and wind observations. The main features of the seasonal cycle are apparent in the results, in particular, the close synchronism of the temperature cycle across the region. In addition, the results show that: variations in the seasonal flux of low salinity water led to short period anomalous salinity values, salinity and temperature anomalies tended to drift with the surface currents, and salinity and temperature changes at the lowest frequencies were caused by displacements of water masses which do not seem to have been forced locally. Fluctuations in heat‐flux and evaporation contributed to variations on a timescale of about three years and it is shown that these gave rise to additional spectral peaks by interacting with the seasonal cycle.