Convergent Shelf Flow at Cape Mendocino

Abstract

Observations taken during tile course of the Northern California Coastal Circulation Study (NCCCS) pilot e.rperiment fiom Mareh through August of 1987 show that shelf currents often converge near Cape Mendocino, resulting in offshore transport. This convergence occasionally, though not always, is accompanied by convergence in the large-scale winds. A cyclonic eddy. roughly 20 km in diameter, is commonly found on the south side of the Cape, where, on the shelf, the average cutv'ents are directed to the north. The water temperature in this area is colder than that observed north of the Cape, where the average current is to the south. Correlation between currents aim the local wind near the Cape is lower than expected from previous results obtained during the Coastal Ocean Dynamics Experiment (CODE) conducted in the same general region, though farther south, along a straight section ~?f the coast. Similarly. temperature and ~'ind fluctuations at a given location are less correlated than they were during CODE. These patterns are not those expected for typical coastal upwelling areas. The coincidence of coldest surface temperatures and persistent northward she![flow is particularly intriguing, as is the lack of colv'elation between currents and wind. Interactions between the shelf flow and the California Cltrrent, variations in the large-scale structure of the wind, the influence of poleward-traveling shelf waves, and the role of Cape Mendoeino in determining flow in the atmosphere as well as in the ocean are discussed as possible causes of the observed convergence. Some of these effects may be responsible Jbr enhanced upwelling near other capes and headlands.

Plastic responses of bryozoans to ocean acidification

“…Although studies of additional replicate populations are needed, our findings are consistent with local adaptation to persistent oceanographic differences between these sites (Sanford and Kelly, 2011). Whereas both of our sites are within the upwelling zone of northern California, VD lies within a recognized center of upwelling, immediately south of Cape Mendocino (Magnell et al, 1990;Feely et al, 2008). Our field sensor data indicate that intertidal habitats at VD receive more consistent upwelling compared with BMR, resulting in more frequent exposure to low Ω aragonite values at VD.…”

Genetic Structure Among 50 Species of the Northeastern Pacific Rocky Intertidal Community

“…In these cases, genetic differences occur closer to Cape Mendocino itself and may be driven by offshore movement at Cape Mendocino of the south-flowing California Current. Surface drifters released from Oregon tend to veer offshore at this point [30] : strong upwelling jets and seasonal offshore currents [39] , [40] may form a barrier that has a structuring effect on some marine populations in this area. This barrier is not impenetrable, however: many species, including some with low pelagic durations, have no discernable structure.…”

Surface circulation and upwelling patterns around Sri Lanka

“…However, numerical experiments indicate that 940 941 there is recirculation to the north of the island, and the upwelling is due mainly to the Kuroshio current encroaching onto the shelf (Chang et al, 2010). On a smaller scale, Magnell et al (1990) show enhanced upwelling at Cape Mendocino resulting from converging currents at the tip of the cape. Through continuity, horizontal divergence at the sea surface results in vertical upwelling of water from depth.…”