Filaments on the Western Iberian Margin: A modeling study

Abstract

AbstractCoastal upwelling filaments off the Western Iberian Margin, detected in AVHRR satellite imagery and in a realistic ROMS simulation of sea surface temperature, were studied in the upwelling seasons (May–October) of 2001–2010. Sea surface temperature data were retrieved from AVHRR satellite imagery and from a realistic ROMS numerical simulation. The development and variability of the observed filaments were characterized and analyzed during each upwelling season of the 10 year period. Filaments were generally found anchored to the main bathymetric and coastal features but off the more regular northern coast of the Western Iberian Margin their locations were more variable. The results from the modeling analysis reproduced well the general features of filament development. Moreover results of model and observation showed very similar characteristics as those found in the earlier study of Haynes et al. (1993). The model output was used to relate filament patterns, eddy activity, and wind forcing. There was a clear relation between upwelling‐favorable wind strength and number and length of filaments, although the relation was weaker in the north of the region. Model filaments were clearly related to eddies only during periods of weak winds. The filament detection method was also applied to a climatologically forced ROMS simulation, which reproduced only gross features of the observed and interannually forced model filament development. This suggests that direct wind forcing and its spatial structure are highly important.