  A possible deepening of the ocean mixed layer was investigated at a selected
point of the Patagonian continental shelf where a significant positive wind
speed trend was estimated. Using a 1-dimensional vertical numerical model
(S2P3) forced by atmospheric data from NCEP/NCAR I reanalysis and tidal
constituents from TPXO 7.2 global model on a long term simulation (1979-2011),
it was found that the mixed layer thickness presents a significant and positive
trend of 10.1 +/- 1.4 cm/yr. Several numerical experiments were carried out in
order to evaluate the impact of the different atmospheric variables (surface
zonal and latitudinal wind components, air temperature, atmospheric pressure,
specific humidity and cloud coverage) considered in this study. As a result it
was found that an increase in the wind speed can be considered as the main
responsible of the ocean mixed layer deepening at the selected location of the
Patagonian continental shelf. A possible increasing in the mixed layer
thickness could be directly impacting on the sea surface temperature.
Preliminary results obtained in this paper show that a slight but significant
cooling in the temperature of the sea upper layer (of the order of 1 C every 50
years) could be happening since some decades ago at the northern Patagonian
continental shelf waters.
