Assimilation of Lagrangian data into a numerical model

Abstract During 1983 and 1984, approximately 40 neutrally buoyant (isopycnal) floats were released into the Gulf Stream. These floats, which were released at approximately weekly intervals, measured their location and depth three times a day for 30–45 days. The basic statistics of these floats are briefly described. This float data set has been applied to the important problem of assimilation of Lagrangian information into a numerical model of the oceanic mesoscale. The assimilation method is a Kalman-filter type technique. Since the processed float data consists of a time series of position, velocity and depth it is natural to use a dynamical model that uses these variables directly. For this purpose a simple shallow-water model utilizing a Lax-Wendroff numerical scheme is used. This type of numerical model has been successfully used in meteorological data assimilation studies. Some results using both one- and two-dimensional versions of this model are described.

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