Abstract
We propose a simple polynomial expression for neutral density and nutrients as a function of potential temperature, pressure and salinity. The expression is applied to the 1988 North Atlantic A16N WOCE meridional section and the polynomial coefficients are calculated using an inverse technique. The resulting polynomials show good skill in reproducing the nutrients and density structure, as verified through an analysis of variance (ANOVA) test. The large-scale changes in the polynomial coefficients occur between equatorial (E), tropical (T), subtropical (ST), and subpolar (SP) waters. The temperature and pressure coefficients experience substantial changes at all transitions (E-T, T-ST, and ST-SP), while the salinity ones only have major variations at the T-ST transition. Mesoscale-like oscillations occur all along the section but are relatively small, except between about 40 and 50°N, in a region of rough bottom topography. The density field is reconstructed using individual and group coefficients, and the contribution of each coefficient is identified. The method is also applied to analyze the neutral density distribution in a nearly identical 2003 section, removing near-surface density values that may be related to different warming/cooling of the surface layer. The results show close resemblances but also some significant variations, which are discussed in terms of interdecadal variability. Hence, we argue that the set of calculated coefficients provides good integral descriptors for the vertical structure of the ocean.
Similar content being viewed by others
References
Boyer, T., S. Levitus, J. I. Antonov, R. A. Locarnini and H. Garcia (2005): Linear trends in salinity for the World Ocean, 1955–1998. Geophys. Res. Lett., 32, L01 604.
Boyer, T., S. Levitus, J. Antonov, R. Locarnini, A. Mishonov, H. Garcia and S. A. Josey (2007): Changes in freshwater content in the North Atlantic Ocean 1955–2006. Geophys. Res. Lett., 34, L16 603.
Holfort, J. and G. Siedler (2001): The meridional oceanic transports of heat and nutrients in the South Atlantic. J. Phys. Oceanogr., 31, 5–29, 373.
Jackett, D. and T. McDougall (1997): A neutral density variable for the world’s oceans. J. Phys. Oceanogr., 27, 237–263, 202.
Johnson, G. C., J. L. Bullister and N. Gruber (2005): Labrador Sea Water property variations in the northeastern Atlantic Ocean. Geophys. Res. Lett., 32, L07 602.
Levitus, S., J. Antonov and T. Boyer (2005): Warming of the world ocean, 1955–2003. Geophys. Res. Lett., 32, L02 604.
Lozier, M. S., W. B. Owens and R. Curry (1995): The climatology of the North Atlantic. Prog. Oceanogr., 36, 1–44, 180.
Machín, F., A. Hernández-Guerra and J. L. Pelegrí (2006): Mass fluxes in the Canary Basin. Prog. Oceanogr., 70(2–4), 416–447.
McDougall, T. (1987): Neutral surfaces. J. Phys. Oceanogr., 17, 1950–1964.
Menke, W. (1984): Geophysical Data Analysis: Discrete Inverse Theory. Academic Press, Inc., Orlando, 260 pp., 46.
Munk, W. and C. Wunsch (1979): Ocean acoustic tomography, a scheme for large scale monitoring. Deep-Sea Res., 26, 123–161.
Pastor, M., J. Pelegrí, A. Hernández-Guerra, J. Font, J. Salat and M. Emellanov (2008): Water and nutrient fluxes off Northwest Africa. Cont. Shelf Res., 28(7), 915–936.
Pelegrí, J. L. and G. T. Csanady (1991): Nutrient transport and mixing in the Gulf Stream. J. Geophys. Res., 96(C2), 2577–2583, 440.
Stramma, L. and F. Schott (1999): The mean flow field of the tropical Atlantic Ocean. Deep-Sea Res. II, 46, 279–303.
Tsuchiya, M., L. Talley and M. McCartney (1992): An eastern Atlantic section from Iceland southward across the Equator. Deep-Sea Res., 39(11/12A), 1885–1917, 145.
Wunsch, C. (1977): Determining the general circulation of the oceans: a preliminary discussion. Science, 196, 871–875, 313.
Wunsch, C. (1996): The Ocean Circulation Inverse Problem. Cambridge University Press, 442 pp.
Zenk, W., B. Klein and M. Schröder (1991): Cape Verde Frontal Zone. Deep-Sea Res., 38(Suppl. 1), 505–530, 467.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Machín, F., Pelegrí, J.L. Integral descriptors of the vertical structure of the ocean. J Oceanogr 65, 499–510 (2009). https://doi.org/10.1007/s10872-009-0043-7
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10872-009-0043-7