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This paper presents new observations of the overflow waters downstream of the Faroe Bank Channel (FBC) and the Iceland-Faroe Ridge (IFR). Between 2006 and 2009, over 17 400 hydrographic profiles were collected during quarterly deployments in the region by autonomous gliders, providing previously unrealized spatial resolution to observations downstream of the FBC. Observations show that the second sill of the FBC coincides with the largest changes in the overflow plume, including significant thinning, widening, and entrainment. Between the second sill and a topographic feature 75 km downstream, the plume bifurcates with the densest portion (65% of the transport), descending below 1000 m. On the IFR, near-bottom velocities are directed alongslope with speeds averaging 21.5 cm s−1. Observations indicate that 80% of baroclinic velocities associated with mesoscale variability of the overflow plume are smaller than the alongslope topographically induced circulation. Evidence of overflow is found at all locations on the Atlantic flank of the IFR. However, the meridionally oriented portion at 13°W has anomalously warm bottom water and divides FBC and eastern IFR overflow from overflow found in the Western Valley. Individual Seaglider sections identify IFR overflow in a narrow current (8-14 km wide) along the Iceland shelf with a mean transport of 0.43 Sv (1 Sv ≡ 106 m3 s−1) with significant variability from days to weeks. A lower-bound estimate of 0.8 Sv of total IFR overflow is presented. These results provide constraints on regional models that inform the representation of this crucial, yet underresolved, region in large-scale ocean and climate models. [ABSTRACT FROM AUTHOR]

The use of new autonomous and Lagrangian platforms (e.g. gliders, drifters, etc.) has revolutionized sampling of the ocean. The incorporation of in vivo chlorophyll-a fluorometers into these platforms for characterizing chlorophyll-a concentrations and phytoplankton biomass has reinforced the need for a thorough 5 understanding of the variability and biases associated with basic fluorescence measurements. Seaglider, a long-range autonomous glider, has been deployed routinely in Northeast Pacific waters off the Washington coast, USA. Measurements of chlorophyll-a fluorescence (proxy for chlorophyll-a concentration) and optical backscattering (proxy for particle concentration) were collected on the continental shelf and along a V-shaped transect that extended 200 km from the continental shelf into deep oceanic waters. Daytime fluorescence quenching (i.e. the reduction in the fluorescence quantum yield often observed during daylight hours) could be detected throughout the dataset, with near-surface daytime fluorescence quenched by as much as 80% during summer. Quenching was 15 observed throughout the region, at all times of year, and to depths greater than 50 m. The degree of quenching was positively correlated with incoming solar radiation and the observed pattern was remarkably similar to what has been observed in other areas, suggesting some degree of universality for the underlying relationship. [ABSTRACT FROM AUTHOR]