The Oceanic Response to Large-Scale Atmospheric Disturbances

Abstract This paper is an analytical and numerical study of the response of the ocean to the fluctuating component of the wind stress as computed from twice-daily weather maps for the period 1973 to 1976. The results are described in terms of (time) mean and rms fields, frequency spectra and horizontal cross spectra, and local cross spectra between oceanic and atmospheric variables. A forcing function with scales strictly larger than O(100 km) induces oceanic motion that is depth independent at periods between the inertial period and ∼300 days. The dynamics is essentially linear so that rectified currents are small, the associated rectified transport amounts to at most 1–2 Sv in the western boundary layer. Root-mean-square currents are typically a few centimeters per second and are most intense in the western part of the basin, and near major topographic features. Fluctuations in the transport of the western boundary layer can be as large as 20–30 Sv. Three distinct frequency bands characterize the wind-i...