Satellite assessment of particulate matter and phytoplankton variations in the Santa Barbara Channel and its surrounding waters: Role of surface waves. Issue 1 (22nd January 2017)

• Record Type: Journal Article
• Authors: Henderikx Freitas, Fernanda; Siegel, David A.; Maritorena, Stéphane; Fields, Erik
• Is Part Of: Journal of geophysical research. Volume 122:Issue 1(2017)
• Page Start: 355
• Page End: 371
• Publication Date: 2017-01-22
• Subjects: role of surface waves -- wind and wave processes -- bio‐optical variability -- ocean color remote sensing -- long‐term trends in phytoplankton -- GSM algorithm; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2016JC012152
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Satellite observations of chlorophyll in coastal waters are often described in terms of changes in productivity in response to regional upwelling processes while optical backscattering coefficients are more often linked to episodic inputs of suspended sediments from storm runoff. Here we show that the surface gravity wave resuspension of sediments has a larger role in controlling backscatter than previously considered. Almost 18 years of SeaWiFS, MODIS, MERIS, and VIIRS satellite imagery of the Santa Barbara Channel, California and its surrounding waters spectrally merged with the Garver‐Siegel‐Maritorena bio‐optical model were used to assess the controls on suspended particle distributions. Analysis revealed that chlorophyll blooms in the warmer portions of the domain occur in phase with SST minima, usually in early spring, while blooms in the cooler regions lag SST minima and occur simultaneously to the strongest equatorward winds every year, often in the summer. Tight coupling between the optical variables was seen in offshore areas, as expected for productive waters. However, values of backscatter near the coast were primarily modulated by surface waves. This relationship holds throughout all seasons and is stronger within the 100 m isobath, but often extends tens of kilometers offshore. This forcing of particle resuspension by surface waves is likely a feature ubiquitous in all coastal oceans characterized by fine sediments. The implication of surface wave processes determining suspended particle loads far beyond the surf zone has large consequences for the interpretation of satellite ocean color signals in coastal waters and potentially redefines the extent of the littoral zone. Key Points: Surface waves control variability of particle backscattering near the coast Climatic indices are shown to drive particle variability during specific portions of the time series Regional and local processes control timing and magnitude of chlorophyll blooms