Drifter observations of the Mediterranean Sea surface circulation/ Todd A Mauerhan

Abstract

Since June 2, 1986, several institutions have conducted a variety of drifter studies within the Mediterranean Sea for scientific and operational purposes. The data from these studies include 521 individual drifters and span over 13 years. This thesis examines these data in an effort to better describe the Mediterranean Sea surface circulation. Interpretation of the data is conducted by calculating Eulerian and Lagrangian statistics and evaluating some of the errors they contain. An Eulerian framework is employed that best represents the surface flow throughout the Mediterranean Sea as a combination of a deterministic mean and fluctuations due to temporal and mesoscale variability. The results of the Eulerian statistics are presented as charts of Mean Kinetic Energy (MKE), Eddy Kinetic Energy (EKE), mean flow, and velocity variance. Seasonality is analyzed in regions where temporal and spatial coverage of drifter observations is adequate. Drifter wind slippage errors and array biases are evaluated to possibly determine a valid correction. The Lagrangian statistics: diffusivity, velocity covariance, and integral time and space scales are computed. The Eulerian and Lagrangian surface circulation statistics computed from the drifters are in general similar, but much improved and more accurate, to those presented in earlier works