Variational Assimilation of Geosat Data into an Eddy-resolving Model of the Gulf Stream Extension Area Schröter, J; Seiler, U; Wenzel, M Journal of Physical Oceanography 23(5): 925-953 1993 0022-3670 10.1175/1520-0485(1993)023<0925:vaogdi>2.0.co;2 https://eurekamag.com/research/062/350/062350977.php