| Abstract |
The simple analytical two-strait and two-basin model built by (Candela et al., 1989), which well describes the barotropic flow through the Strait of Gibraltar forced by homogeneous fields of oscillating atmospheric pressure over the Eastern and Western Mediterranean, was improved by allowing the coefficient of linear bottom friction lambda to be frequency-dependent. The coefficient lambda is here proportional to the magnitude of the volume flow through the Strait of Gibraltar, and therefore increases with the frequency at very low frequencies, starting from zero. After reaching the extreme, which was tuned to be close to the value of frequency-independent lambda, the coefficient slowly decreases with frequency. Both approaches, with frequency-dependent and independent lambda give almost the same frequency dependence for all variables, therefore the disagreement between model values and cross-spectral analysis remains at high frequencies. Using the values of cross-section dimensions proposed by Candela et al. the estimates of the drag coefficient are by about two orders of magnitude too high in both approaches. If the geostrophic control of the flow through the Strait of Gibraltar plays a role at low frequency range also when friction is included, then its upper frequency limit is estimated to be approximately 4 x 10(-3) cph. |
