Analysis of internal soliton signals and their eastward propagation in the Alboran Sea: exploring the effect of subinertial forcing and fortnightly variability

Abstract

Internal waves are commonly observed in oceans and lakes where high stratification exists. In the present study in the Strait of Gibraltar, we analyse internal soliton signals recorded in different locations in their eastward propagation from their release point (Camarinal Sill) to the continental slope of the northwestern Alboran Sea. Moreover, the effect of subinertial forcing on the release of solitons is also explored. The internal soliton activity was assessed from different approaches: (i) in-situ data (i.e., current and temperature measurements or High-Frequency Radar), (ii) numerical modelling, and (iii) an analytical approach. The arrival of solitons over the continental slope of the north-western Alboran Sea showed fortnightly variability in both number (occurrence) and amplitude during spring tides when compared with during neap tides. The observed arrival times of the solitons oscillated between 14 (spring tides) and 20 h (neap tides). Nevertheless, to provide a comprehensive explanation for the fluctuations in travel times, it is necessary to consider the subinertial variability driven by atmospheric forcing, which impacts both the flow in the Strait of Gibraltar and the mesoscale patterns in the Alboran Sea (e.g., the Coastal Cyclonic Gyre)