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Internal wave observations from ERS-2 SAR in the Patagonian Shelf

Dohyung Koo(1) and Ian Robinson(1)

(1) National Oceanography Centre, Southampton, Waterfront Campus, Southampton, SO14 3ZH, United Kingdom


ERS-2 SAR PRI data (ordered via project C1P. 2521) indicate the existence of internal waves in the Patagonian Shelf from austral spring to early autumn. Here we will present a series of ERS SAR observations during the year of 2001. During the spring tide, the rank-ordered internal waves propagate shoreward in the northern part of the shelf region. However, over the deeper slope region, SAR imagery show along-slope propagation internal waves where the Malvinas/Falkland Current flows equatorward. Also, it is clearly visible that the intense current leads to strong refraction of internal waves. Generally we expect internal wave speed over greater depths to be accelerated but these data show the opposite. Hence we assume that the refraction of internal wave crests is caused by the Current. Additionally the different direction of propagation and smaller signatures of internal waves are observed over the Current regime. The availability of SAR data has allowed us to map the space-time distribution of internal waves in a region where in situ observations are sparse. No internal waves were observed on the shelf region (< 50 m) and were concentrated near the shelf-break. We can expect an internal wave energy sink to relate to high chlorophyll a concentrations along the shelf-break during austral summer. Interaction and breaking of internal waves can enhance nutrients at the surface during the summer. The paper will demonstrate the synergy between SAR and ocean colour satellite data for the study of biophysical interactions in the ocean.



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