Coastal Upwelling Front Detection off Central Chile (36.5–37°S) and Spatio-Temporal Variability of Frontal Characteristics

• Published in: Remote sensing (Basel, Switzerland) Switzerland), 2018-04, Vol.10 (5), p.690
• Main Authors: Oerder, Vera, Bento, Joaquim, Morales, Carmen, Hormazabal, Samuel, Pizarro, Oscar
• Format: Article
• Language: English
• Subjects: Atmospheric forcing; climate change; Coastal ecosystems; coastal upwelling front detection; Coastal waters; Cold; Eastern Boundary Upwelling System; Methods; Oceanography; Probability; Radiometers; Sea surface temperature; Seasonal variations; Upwelling; upwelling spatio-temporal variability; Wind
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs10050690

In Eastern Boundary Upwelling Systems, cold coastal waters are separated from offshore by a strong cross-shore Sea Surface Temperature (SST) gradient zone. This upwelling front plays a major role for the coastal ecosystem. This paper proposes a method to automatically identify the front and define its main characteristics (position, width, and intensity) from high resolution data. The spatio-temporal variability of the front characteristics is then analyzed in a region off Central Chile (37°S), from 2003 to 2016. The front is defined on daily 1 km-resolution SST maps by isotherm T0 with T0 computed from mean SST with respect to the distance from the coast. The probability of detecting a front, as well as the front width and intensity are driven by coastal wind conditions and increased over the 2007-2016 period compared to the 2003-2006 period. The front position, highly variable, is related to the coastal jet configuration and does not depend on the atmospheric forcing. This study shows an increase by 14% in the probability of detecting a front and also an intensification by 17% of the cross-front SST difference over the last 14 years. No trend was found in the front position.