Articles | Volume 13, issue 4
Research article
07 Jul 2017
Research article |  | 07 Jul 2017

Differences between 1999 and 2010 across the Falkland Plateau: fronts and water masses

M. Dolores Pérez-Hernández, Alonso Hernández-Guerra, Isis Comas-Rodríguez, Verónica M. Benítez-Barrios, Eugenio Fraile-Nuez, Josep L. Pelegrí, and Alberto C. Naveira Garabato

Abstract. Decadal differences in the Falkland Plateau are studied from the two full-depth hydrographic data collected during the ALBATROSS (April 1999) and MOC-Austral (February 2010) cruises. Differences in the upper 100 dbar are due to changes in the seasonal thermocline, as the ALBATROSS cruise took place in the austral fall and the MOC-Austral cruise in summer. The intermediate water masses seem to be very sensitive to the wind conditions existing in their formation area, showing cooling and freshening for the decade as a consequence of a higher Antarctic Intermediate Water (AAIW) contribution and of a decrease in the Subantarctic Mode Water (SAMW) stratum. The deeper layers do not exhibit any significant change in the water mass properties. The Subantarctic Front (SAF) in 1999 is observed at 52.2–54.8° W with a relative mass transport of 32.6 Sv. In contrast, the SAF gets wider in 2010, stretching from 51.1 to 57.2° W (the Falkland Islands), and weakening to 17.9 Sv. Changes in the SAF can be linked with the westerly winds and mainly affect the northward flow of Subantarctic Surface Water (SASW), SAMW and AAIW/Antarctic Surface Water (AASW). The Polar Front (PF) carries 24.9 Sv in 1999 (49.8–44.4° W), while in 2010 (49.9–49.2° W) it narrows and strengthens to 37.3 Sv.

Short summary
The decadal differences between the ALBATROSS (April 1999) and MOC2-Austral (February 2010) hydrographic cruises are analyzed. Changes in the intermediate water masses beneath seem to be very sensitive to the wind conditions existing in their formation area. The Subantarctic Front is wider and weaker in 2010 than in 1999, while the Polar Front remains in the same position and strengthens.