Part of this work has been supported by the European Union Environment and Climate project DUACS (ENV4-CT96-0357). The altimeter products have been produced by the CLS Space Oceanography Division as part of the European Union Environment and Climate project AGORA (ENV4-CT9560113) and DUACS (ENV4-CT96-0357). Author AT received support from the NERC through a WOCE grant during the early part of this work. We thank Jocelyn Williams for drawing Fig. 1 and Michael McPhaden for supplying us with the CTD data used in Figure 12 and Billy Kessler for the observation data used in Fig. 11, including extending his analysis to the end of 1998 for us.
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