Chemical signature of intermediate water masses along western Portuguese margin
- 97 Downloads
Although the circulation of intermediate water masses in the eastern North Atlantic remains poorly defined, the presence of fresher intermediate waters, the Sub-Artic (SAIW) and the Antarctic Intermediate Water (AAIW), as well the saline intermediate Mediterranean Water (MW), has been tracked using biogeochemical properties. Here we assess the hydrographic and chemical structures of intermediate waters along the western Portuguese margin by examining the vertical distributions and property-property plots of chemical tracers (oxygen and nutrients). AAIW was traced by low oxygen and high nutrients, while SAIW was recognized by low nutrients. The Mediterranean Water (MW) undercurrent is shown to spread towards the eastern flank of Gorringe bank. Concurrently, the fresher waters gained salt by direct incorporation of MW, while this water was enriched in nutrients on its way northward and westward owing, to a great extent, to the entrainment of an AAIW branch. The distributions of nutrients and apparent oxygen utilization are discussed in terms of regional ocean circulation. Our analysis suggests a circulation pattern of the various intermediate waters along the western Portuguese margin: MW extends all over the area, but its presence is more pronounced around cape St. Vincent; SAIW apparently moves southward, reaching the Gorringe bank region, and AAIW flows northward along the coast and around the bank.
KeywordsIntermediate water masses biogeochemical properties eastern North Atlantic Portuguese margin
Unable to display preview. Download preview PDF.
- Broecker, W. S. and T.-H. Peng (1982): Tracers in the Sea. Eldigo Press, Palisades, NY, 690 pp.Google Scholar
- Carrit, D. E. and J. H. Carpenter (1966): Comparison and evaluation of currently employed modifications of the Winkler method for determining oxygen in seawater. A NASCO re port. J. Mar. Res., 24, 286–318.Google Scholar
- Coelho, H. and R. Santos (2003): Enhanced primary production over seamounts: a numerical study. 4o Simpósio sobre a Margem Ibérico Atlântica, 3 pp.Google Scholar
- Hinrichsen, H. H. and M. Tomczak (1993): Optimum multiparameter analysis of the water mass structure in the western North Atlantic Ocean. J. Geophys. Res., 98, 10,155–10,169.Google Scholar
- Koutsikopoulos, C. and B. Le Cann (1996): Physical processes and hydrological structures related to the Bay of Biscay anchovy. Scient. Mar., 60(Supl. 2), 9–19.Google Scholar
- Ríos, A. F., F. Fraga and F. F. Pérez (1989): Estimation of coefficients for the calculation of “NO”, “PO” and “CO”, starting from elemental composition of natural phytoplankton. Scient. Mar., 53, 779–784.Google Scholar
- UNESCO (1981): Background papers and supporting data on the Practical Salinity Scale 1978. UNESCO Tech. Paper Mar. Sci., 37, 1–144.Google Scholar
- Zenk, W. (1970): On temperature and salinity structure of the Mediterranean water in the N.E. Atlantic. Deep-Sea Res., 17, 627–632.Google Scholar