A method of control is developed in order to compute the variability of the velocity and pressure (u, p) in an oceanic doman Omega during a time T. The observation is the variability of p of Gamma(0) x]0, T[, where Gamma(0) is the upper surface of Omega and corresponds to the undisturbed sea surface. The observation is deduced from satellite data. The control is the variability of the wind-stress f, which acts as the forcing of the perturbation. The mean circulation in Omega is supposed to be known. The equations verified by (u, p) are linearized around this mean circulation. The continuity of the application : f --> (u(f),p(f)) in convenient functional spaces is proved. We deduce from this result the existence and uniqueness of an optimal control, which is characterized by a set of equations including the direct problem of linearized Navier-Stokes type verified by (u,p) and the adjoint problem. The cost function and consequently the optimal control depend on a real parameter alpha. We prove the convergence of the sequence (f(alpha)), when alpha tends to 0, toward a wind-stress f which minimizes the distance between the observed and computed pressures. This result is obtained by means of minimizing sequences.