Manifestation of two meddies in altimetry and sea-surface temperature 1Centro de Oceanografia, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lissabon, Portugal
05 Mar 2013
2Departamento de Engenharia Geográfica, Geofísica e Energia (DEGGE), Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lissabon, Portugal
Received: 31 August 2012 – Published in Ocean Sci. Discuss.: 27 September 2012 Abstract. Two meddies were identified in the Iberian Basin using shipboard ADCP
(Meddy 1) and Argo float (Meddy 2) in contrasting background conditions.
Meddy 1 was observed while interacting with the Azores Current (AzC), while
Meddy 2 was observed in a much calmer dynamical background, north from the AzC
jet. In both cases the meddies formed a clear anticyclonic surface signal,
detectable in altimetry as well as in sea-surface temperature (SST).
Analysis of the in situ observations of the dynamic signal over Meddy 1
showed that the signal, generated by the moving meddy, dominated the AzC
dynamics at least up to the base of the seasonal thermocline even at the late
stages of its interaction with the jet. The centre of rotation of the surface
signal was shifted south-westward from the axis of the meddy by about 18 km,
and its dynamic radius was 2 times bigger than that of the meddy.
In the centre of the anticyclonic surface signals of both meddies, SST was
colder than that of the surrounding water, in contrast to warm SST anomalies
in the cores of surface anticyclones generated by meandering surface
currents. The latter difference gives ground for identification of meddies
(as well as other sub-surface anticyclones) in comparatively dynamically calm
regions using coupled altimetry–SST remote sensing data. An identification
of Meddy 1 prior to the shipboard ADCP measurements was the first
successful experience. At the same time, SST anomalies over the meddies were
rather weak, often unstable and statistically significant only over periods
Revised: 22 December 2012 – Accepted: 08 February 2013 – Published: 05 March 2013
Citation: Bashmachnikov, I., Boutov, D., and Dias, J.: Manifestation of two meddies in altimetry and sea-surface temperature, Ocean Sci., 9, 249-259, doi:10.5194/os-9-249-2013, 2013.