Internal solitary waves from L-band SAR over the Argentine inner Patagonian shelf

Abstract

Internal waves represent an important mechanism of energy exchange influencing primary production through the turbulent transport of nutrients and changes in the intensity of light available for photosynthesis. Internal solitary waves (internal solitons) appear in packages and retain their shape and speed even after interacting with other internal waves. We detected solitons in the inner Patagonian shelf with the active L-band microwave satellite sensor (ALOS-PALSAR). Packages found in the satellite images were digitized. Generation mechanisms and propagation speeds were assessed using historical CTD profiles near the detected waves, assuming linear theory and atwo-layer vertical structure. The estimated propagation speeds of the waves ranged from 0.5 to 0.7m s−1. The generation regimes of waves originated at asill near the coast were classified as subcritical or near-critical according to the Froude number. We hypothesize that at this site, the generation mechanism starts leeward from the sill (lee wave mechanism), after the relaxation of the tidal current. Generation mechanisms of waves detected elsewhere over the shelf are not so obvious. More images are necessary to better determine the wave generation site. We will continue the analysis with L-band images aboard the SAOCOM 1A (CONAE), put in orbit in October 2018.