CoAuthors

Laura Ruiz Etcheverry (UBA-CONICET-CIMA-IFAECI, Argentina); Celeste López Abbate (IADO-CONICET, Argentina)

Marine fronts are narrow boundaries between two water masses with different physical properties. Fronts are dynamic, meaning they vary in space, time, and intensity. Therefore, their detection based on a fixed value of a physical variable such as Absolute Dynamic Topography (ADT) may not be the most optimal method. In order to detect the spatial and temporal variations of the most important fronts in the Drake Passage (DP), namely the Subantarctic Front (SAF), the Polar Front (PF), and the Southern Front of the Circumpolar Antarctic Current (SCACC), we proposed a methodology that utilizes 27 years of daily satellite altimetry maps. This methodology involves calculating the probability density function (PDF) of daily ADT in a polygon with a fixed area (5º width x 12.5º length) that moves eastward every 3º from 73ºW to 53ºW. Water masses are identified as relative maximas in the PDF associated with a value of ADT, while the frontal zone is represented by a minimum located between these maximas. In each box, the minimum of the PDF and the associated ADT value were detected, and the connection between boxes was established by finding the ADT value closest to the ADT value of the previous box. The results at a climatological scale show good agreement with the mean positions of SAF, PF and SACCF found by Orsi et al. (1995). The detected fronts exhibit some spatial variation during a climatological year. The next step will be to improve the technique by using a greater number of boxes in the DP to refine the front detection and study the interannual variability.

Keywords: marine fronts, Drake Passage, absolute dynamic topography, probability density function.