Resumen

JERONIMO, G  y  GOMEZ-VALDES, J. Mean temperature and salinity along an isopycnal surface in the upper ocean off Baja California. Cienc. mar [online]. 2006, vol.32, n.4, pp.663-671. ISSN 0185-3880.

The mean thermodynamic fields along the 25σ_θ surface in the southern region of the California Current were studied using the 1998-2005 data from the IMECOCAL (Mexican Research of the California Current) program. The method of objective analysis was implemented and subsequently validated by Monte Carlo tests. The optimum correlation scales, in parallel and perpendicular direction to the coast, were L_Y = 110 km and L_X = 90 km, respectively. In agreement with geostrophic balance, the mean 25σ_θ surface was inclined, with the shallower part (38 m) near the shore and the deeper part (68 m) offshore. The area farthest from the coast was dominated by eddies. Extensive areas of low temperature (<14.0°C) and salinity (<33.6) were found to the north of Point Eugenia, while higher temperatures (>14.4°C) and salinities (>33.7) occurred to the south. Point Eugenia, therefore, is generally the converging zone where warm, salty equatorial water meets the cold, less salty subarctic water. The variability of the thermodynamic fields revealed the presence of three different zones: the northern (29-31°N) low variability zone, the southern (25-27.5°N) high variability zone, and the central zone of moderate variability. The distinction of these three zones was corroborated by analysis of temperature and salinity gradients, as well as by in situ vertical profiles.

Palabras llave : 25σ_θ surface; potential temperature; salinity; objective analysis; IMECOCAL.