Tidal currents in the Malta – Sicily Channel from high-frequency radar observations

Abstract

Two years of sea surface current measurements acquired since August 2012 by High-Frequency SeaSonde radars over the relatively shallow shelf area dividing the Maltese Islands from Sicily (the Malta - Sicily Channel), are used to characterize the surface tidal currents in the region. Tidal currents are generally weak and concentrated in the semidiurnal and diurnal bands, barely exceeding 3 cm s1 in the semi- diurnal band (M2, S2), and below 6 cm s1 in the diurnal band (K1, O1). In the middle part of the basin, the M2 currents oscillate along the main Channel axis; on the contrary the S2 oscillations are oriented along the energetic Atlantic Ionian Stream (AIS) flow. Diurnal tides have a more circular pattern, also following the AIS path and with a significant intensification in proximity of the shelf break, thus suggesting a substantial contribution from internal tides in the region. Phase contours suggest the presence of amphidromic points for both the semidiurnal and diurnal constituents, located in the central area of the Channel for S2, O1 and K1, but slightly shifted towards north-west for the M2 component.