Satellite assessment of particulate matter and phytoplankton variations in the Santa Barbara Channel and its surrounding waters: Role of surface waves

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.

Sea Surface Temperature Imagery Elucidates Spatiotemporal Nutrient Patterns for Offshore Kelp Aquaculture Siting in the Southern California Bight

“…The United States portion of the Southern California Bight is a part of the California Current System that stretches from Point Conception to San Diego, California, and experiences a Mediterranean climate of cool, wet winters and warm, dry summers. Seasonal upwelling of cool, nutrient rich waters is driven by intensified winds in late winter and spring along the west coast of the United States (Harms and Winant, 1994;Otero and Siegel, 2004;Henderikx-Freitas et al, 2016). This season is followed by a period of reduced upwelling, when waters warm and stratify throughout the summer and fall months.…”

Quality of a fished resource: Assessing spatial and temporal dynamics

“…Sea urchin larvae begin to feed within the first week of life and remain in the water column for about 40 days (ranging from 27 to 131 days depending on food and temperature; [ 61 , 62 ]). Recent data (1997–2015) suggest that the Santa Barbara Channel experiences extreme inter-annual variability in the timing of chlorophyll peaks, but in general blooms begin between March and June, with some years starting in February and some peaking in September [ 63 , 64 ]. However, red sea urchin spawning begins and peaks in December and January and appears to continue through June (Table A in S3 Appendix ).…”

Formation, Development, and Propagation of a Rare Coastal Coccolithophore Bloom

“…The average significant wave height at NDBC buoy 46216 (Figure ) was small at 0.77 m, and there was no measurable river runoff in the region around the time of the study period. Furthermore, satellite‐based observations of suspended particles (based on the particulate backscattering coefficient at 442 nm) in the SBC region were anomalously low during 2015 (Henderikx Freitas et al, ).…”

“…Instead, initial satellite detection is typically at the beginning of the populations' stationary growth phase when shed coccoliths are abundant and waters have been largely depleted of nutrients by the developing bloom (Balch et al, 1993;Balch et al, 1996;Holligan et al, 1993). Additionally, satellite studies of coastal phytoplankton dynamics are often limited by cloud cover or suspended sediments obscuring the blooms (Henderikx Freitas et al, 2017;Tyrrell & Merico, 2004).…”