Sea Surface Circulation Structures in the Malta-Sicily Channel from Remote Sensing Data

Abstract

The Malta-Sicily Channel is part of the Sicily Channel system where water and thermohaline properties between the Eastern and Western Mediterranean basins take place. Several mesoscales features are detached from the main circulation due to wind and bathymetric forcing. In this paper, surface circulation structures are studied using different remotely sensed datasets: satellite data (absolute dynamic topography, Cross-Calibrated Multi-Platform wind vector analysis, satellite chlorophyll and sea surface temperature) and high frequency radar data. We identified high frequency motions (at short time scales—hours to days), as well as mesoscale structures fundamental for the understanding of the Malta-Sicily Channel circulation dynamics. One of those is the Malta-Sicily Gyre; an anticyclonic structure trapped between the Sicilian and Maltese coasts, which is poorly studied in the literature and often confused with the Malta Channel Crest and the Ionian Shelf Break Vortex. In order to characterize this gyre, we calculated its kinetic properties taking advantage of the fine-scale temporal and spatial resolution of the high frequency radar data, and thus confirming its presence with an updated version of the surface circulation patterns in the area.

First report of Alvania scuderii Villari, 2017 (Gastropoda: Mollusca) from Tyrrhenian Sea: Some biogeographic implications

“…Such coastal waters, that are colder than the close Ionian and Tyrrhenian typical water masses, have different origin, since southward they are tied to a wind-induced upwelling regime (Levi et al, 2003), whilst northward the effect of the Messina Strait tidal upwelling is recognizable (Bôhm et al, 1987). The records from the isle of Linosa, although concerning an area that is almost peripheral in respect to the core of such peculiar water-masses, can be explained by the Atlantic-Ionian Current pathway, one branch of which originates an anticiclonic gyre circling around Linosa, before flowing towards Sicily (Reyes Suarez et al, 2019). We may suppose, in agreement with Cuttitta et al (2016), that mesoscale oceanographic structures play a key role in shaping the actual distribution of A. scuderii.…”

Observations of Surface Currents and Tidal Variability Off of Northeastern Taiwan from Shore-Based High Frequency Radar

“…HFRs hav lized to derive wind-driven surface currents in many studies and to illustrate tion between coastal currents and wind. Coastal currents respond rapidly to w with currents changing speed or reversing in response to changing wind pa wind stresses [17][18][19][20]. Since the angle between two observed vectors (e.g., cu…”

“…Ocean currents can be depicted as a blend of geostrophic and ageostrophic terms, with the latter representing wind-driven ageostrophic currents [17]. HFRs have been utilized to derive wind-driven surface currents in many studies and to illustrate the connection between coastal currents and wind.…”

“…HFRs have been utilized to derive wind-driven surface currents in many studies and to illustrate the connection between coastal currents and wind. Coastal currents respond rapidly to wind effects, with currents changing speed or reversing in response to changing wind patterns and wind stresses [17][18][19][20]. Since the angle between two observed vectors (e.g., currents and wind) can be a function of time, one method to investigate correlations is to find the average angular displacement between two vectors.…”

Ocean Exchange and Circulation

“…On the other hand, generation mechanisms like wind curl and dense water flow of the mesoscale eddies in the Ionian Sea (central Mediterranean) were addressed and some comparisons between the two forcing mechanisms were discussed in the paper by Menna et al [5]. The Sicily Channel, in between the eastern and western Mediterranean basins, is another area characterized by large mesoscale variability and water mass exchanges that was analyzed in the paper by Reyez-Suarez et al [6]. In this paper, data obtained by the High Frequency (HF) radar enabled authors to identify semi-permanent gyres, which were clearly evident from altimetry data also.…”