Using Radar Altimeter data to study mesoscale ocean circulation in enclosed seas

by      Julia Figa, jfiga@estec.esa.nl, +31 71 565 5370
        Johnny Johannessen, jjohannes@jw.estec.esa.nl, +31 71 565 5959

        Earth Sciences Division, ESTEC
        Posbus 299, 2200 AG Noordwijk, The Netherlands
        FAX: +31 71 565 5675

	Marc A. Garcia, garcial@etseccpb.upc.es
	Laboratori d'Enginyeria Maritima, Universitat Politecnica de Catalunya
	Gran Capita s/n. 08034, Barcelona, Spain.
	Tel: +34 3 401 6471
	FAX: +34 3 401 7357


The Radar Altimeter (RA) data has proved to be of significant value in
basin and global scale circulation. This study intends to evaluate the
feasibility of using RA data in the enclosed sea of the Bransfield
Strait, in Antarctica. This area is characterized by a coastal, channel
type, circulation regime, generally less intense than the Gulf Stream or
the Kuroshio Current, and with tidal current variability of
approximately the same magnitude as the mesoscale background current. 

The RA data provided by the TOPEX/POSEIDON and ERS-1 satellites in the
period of 1992 to 1994 are used. A classical repeat track analysis is
performed, in order to estimate the residual sea surface topography. The
corresponding time-varying, mesoscale surface geostrophic currents are
then computed.

Two different tide models have been applied in the residual sea surface
topography computation, in order to assess the impact of the tide
corrections. These are the Texas University global tide model and a zoom
of Le Provost hydrodynamic model over the Bransfield.

The RA resaults are further validated by an in situ data base consisting
of current meter measurements and CTD observations. Possible evidences
of mesoscale circulation are discussed.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry