1. Thermohaline and dynamical properties of Mediterranean Water eddies
J.Medeiros (1), I.Bashmachnikov (1,2)
(1) Centro de Oceanografia, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Lisboa, Portugal, e- mail:
(2) Departamento de Engenharia Geográfica, Geofísica e Energia (DEGGE), Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Lisboa, Portugal.
Statistics over the 46 meddies distributed over the six areas are presented in an attempt to study their geometric, thermohaline and dynamic properties as a function of distance from the Iberian coast.
As we can see up to 600 km we have an expected decrease in maximum salinity, an increase in dynamical diameter. From 600 km and farther we have found different behaviour of these properties depending if they are northern or southern of the Azores Current.
Meddies distributed into six areas (A1 to A6) in the North-East Atlantic. Squares represent the 20 meddies with vertical information. The white line at 35 oN marks one of the zonal front of the Azores Current
Maximum Salinity Anomaly for the 46 meddies. Size of the marker are proportional to their dynamic diameter. The white line at 35 oN marks one of the zonal front of the Azores Current
Introduction
A bibliographic review was made for 46 Mediterranean Water eddies (meddies) thoroughly covered with observations. For each meddy, we have collected all the geographical, geometric, termohaline and dynamic information available.
From the 46, only for 20 we were able to retrieve vertical information from vertical sections. For these, we have computed dynamical quantities such as potential vorticity (PV) and the Burger Number (Bl) among others.
For all the 46, we were able to compute the Salinity Volume (Svol) and Rossby Number (R0).
Statistics over the six areas for the 46 meddies for : Maximum salinity, Dynamical diameter and Vertical extension. Each box represent the statistic mean, and the errorbars are refer to the 95% level of confidence error interval.
From 600 km, statistics refer to meddies north of the Azores Current ( black line) and south of the Azores Current ( red line ).
The presented results, show a clearly increase in Svol and a decrease in the R0 up to 600 km away from shore. From 600 km to farther away, again we can expect distinct distribuitions for the meddies statistics north and south of the Azores Current.
For PV, we found an expected increase up to 1600 km. From this point, meddies north and south the Azores current show similar pattern altough in diferent intensities.
Statistics over the six areas for the 46 meddies for the Salinity Volume. Each box represent the statistic mean, and the errorbars are refer to the 95% level of confidence error interval. From 600 km, statistics refer to meddies north of the Azores Current ( black line) and south of the Azores Current ( red line ).
Statistics over the six areas for the 46 meddies for the Rossby Number. Each box represent the statistic mean, and the errorbars are refer to the 95% level of confidence error interval. From 600 km, statistics refer to meddies north of the Azores Current ( black line) and south of the Azores Current ( red line ).
Statistics over the six areas for the 20meddies for the Potential Vorticity. Each box represent the statistic mean, and the errorbars are refer to the 95% level of confidence error interval. From 600 km, statistics refer to meddies north of the Azores Current ( black line) and south of the Azores Current ( red line ).
Concluded Remarks
From the statistics we can underly an increase in the termohalines and geometric properties up to 600 km away from shore. This increase may be due to meddy merging process that can be most frequent to ocurr near the formation sites.
Farther than 600 km and taking into account the Azores Current, we can denote that the meddies that cross the current suffer a loss in Salinity Volume, but most interesting is that they seem to gain relative vorticity becouse of the increase in R0.
The behaviour of PV away from shore, specially from the 600 km indicates that the dynamic feature is not the main influent, so we can expect that the stratification has a more significant influence.
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Aknowledgements : This study had the support of Fundação para a Ciência e Tecnolgia (FCT) and the project MEDTRANS - PTDC/MAR/117265/2010