scholarly journals Near-inertial and tidal currents detected with a vessel-mounted acoustic Doppler current profiler in the western Mediterranean Sea

2003 ◽  
Vol 108 (C5) ◽  
Author(s):  
E. Garcia-Gorriz
2004 ◽  
Vol 34 (3) ◽  
pp. 685-692 ◽  
Author(s):  
Jesús García Lafuente ◽  
Javier Delgado

Abstract An accidentally released drifter in the eastern section of the Strait of Gibraltar, whose successive positions were tracked by the Argos surveillance system, was advected more than 170 km around the western Alboran gyre in the Alboran Sea of the western Mediterranean Sea during four days. The drifter trajectory along the gyre's periphery was wavelike around a hypothetical smoothed streamline, with a period of 35 h and an amplitude of approximately 2 km. Temperature observations confirm the wavelike nature of the trajectory. Neither tidal currents within the Alboran basin nor wind-related forcing are able to explain the observed path. The interaction of the incoming Atlantic jet and the western Alboran gyre at the place where they meet together with the existence of relative vorticity pulses of the Atlantic jet associated with tidal currents in the strait is put forward as a likely mechanism that generates short-scale eddies in which the drifter could have been trapped. The subsequent advection of such an eddy around the gyre would depict the observed wavelike trajectory.


Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 631-649 ◽  
Author(s):  
Davide Guerra ◽  
Katrin Schroeder ◽  
Mireno Borghini ◽  
Elisa Camatti ◽  
Marco Pansera ◽  
...  

Abstract. Diel vertical migration (DVM) is a survival strategy adopted by zooplankton that we investigated in the Corsica Channel using acoustic Doppler current profiler (ADCP) data from April 2014 to November 2016. The principal aim of the study is to characterize migration patterns and biomass temporal evolution of zooplankton along the water column. The ADCP measured vertical velocity and echo intensity in the water column range between about 70 and 390 m (the bottom depth is 443 m). During the investigated period, zooplanktonic biomass had a well-defined daily and seasonal cycle, with peaks occurring in late winter to spring (2015 and 2016) when the stratification of the water column is weaker. Zooplanktonic biomass temporal distribution in the whole water column is well correlated with biomass of primary producers, estimated with satellite data. Zooplanktonic blooming and non-blooming periods have been identified and studied separately. During the non-blooming period zooplanktonic biomass was most abundant in the upper and the deep layers, while during the blooming period the upper-layer maximum in zooplanktonic biomass disappeared and the deep layer with high zooplanktonic biomass became thicker. These two layers are likely to correspond to two different zooplanktonic communities. The evolution of zooplanktonic biomass is well correlated with chlorophyll, with phytoplankton biomass peaks preceding the upper-layer secondary production by a lag of about 3.5 weeks. Nocturnal DVM appears to be the main pattern during both periods, but reverse and twilight migration are also detected. Nocturnal DVM was more evident at mid-water than in the deep and the upper layers. DVM occurred with different intensities during blooming and non-blooming periods. One of the main outcomes is that the principal drivers for DVM are light intensity and stratification, but other factors, like the moon cycle and primary production, are also taken in consideration.


2014 ◽  
Vol 59 (1) ◽  
Author(s):  
Salvatore Mele ◽  
Maria Pennino ◽  
Maria Piras ◽  
José Bellido ◽  
Giovanni Garippa ◽  
...  

AbstractThe metazoan parasite assemblage of the head of 30 specimens of the Atlantic chub mackerel (Scomber colias) from the western Mediterranean Sea was analysed. Eight species of parasites were found, four mazocraeid monogeneans: Grubea cochlear (prevalence = 10%), Kuhnia scombercolias (59%), K. scombri (52%), Pseudokuhnia minor (86%); three didymozoid trematodes: Nematobothrium cf. faciale (21%), N. filiforme (41%), N. scombri (7%); and one laerneopodid copepod: Clavelissa scombri (7%). Results were compared with previously published data from 14 localities of the eastern Mediterranean Sea and the Atlantic Ocean, using non-parametric univariate and multivariate analyses, and the whole parasite fauna of S. colias was compared with that of the congeners (S. australasicus, S. japonicus and S. scombrus). Parasites showed to reflect the biogeographical and phylogenetic history of host. From a methodological point of view, the use of both non-parametric univariate and multivariate techniques proved to be effective tools to detect dissimilarities between parasite assemblages.


2021 ◽  
Vol 9 (2) ◽  
pp. 208
Author(s):  
Valentina Vannucchi ◽  
Stefano Taddei ◽  
Valerio Capecchi ◽  
Michele Bendoni ◽  
Carlo Brandini

A 29-year wind/wave hindcast is produced over the Mediterranean Sea for the period 1990–2018. The dataset is obtained by downscaling the ERA5 global atmospheric reanalyses, which provide the initial and boundary conditions for a numerical chain based on limited-area weather and wave models: the BOLAM, MOLOCH and WaveWatch III (WW3) models. In the WW3 computational domain, an unstructured mesh is used. The variable resolutions reach up to 500 m along the coasts of the Ligurian and Tyrrhenian seas (Italy), the main objects of the study. The wind/wave hindcast is validated using observations from coastal weather stations and buoys. The wind validation provides velocity correlations between 0.45 and 0.76, while significant wave height correlations are much higher—between 0.89 and 0.96. The results are also compared to the original low-resolution ERA5 dataset, based on assimilated models. The comparison shows that the downscaling improves the hindcast reliability, particularly in the coastal regions, and especially with regard to wind and wave directions.


2007 ◽  
Vol 105 (1-2) ◽  
pp. 101-117 ◽  
Author(s):  
Tommaso Tesi ◽  
Stefano Miserocchi ◽  
Miguel A. Goñi ◽  
Leonardo Langone

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