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Abstract: Backscatter data from moored acoustic Doppler current profilers (ADCPs) are analysed to quantify the diel vertical migration patterns of zooplankton on the Newfoundland Shelf, Canada. Data from 11 moorings [...]

With increasing pressure for a more ecological approach to marine fisheries and environmental management, there is a growing need to understand and predict changes in marine ecosystems. Biogeochemical and physical [...]

The synoptic variability in adjusted sea level at coastal tide gauge stations around the North Atlantic can be studied by use of a barotropic shallow-water model, using time scales of a few days or months. The resolution of the model is 1/3 degree latitude and 0.4 degree longitude. A comparison of the model results with coastal tide gauge data indicates that coherence squared is in the range 0.5-0.75 over a 3-10 day period. The model-computed variability inside the ocean is also discussed.

Ocean gliders can provide high spatial and temporal resolution data and target specific ocean regions at a low cost compared to ship-based measurements. An important gap, however, given the need for carbon measurements, is the lack of capable sensors capable for glider-based CO2 measurements. We need to develop robust methods to evaluate novel CO2 sensors for gliders. Here we present results from testing the performance of a novel CO2 optode sensor (Atamanchuk et al., 2014), deployed on a Slocum glider, in the Labrador Sea and on the Newfoundland Shelf. We demonstrate our concept of validating data from this novel sensor during a long glider deployment using a secondary autonomous observing platform - the SeaCycler. Comparing data between different sensors and observing platforms can improve data quality and identify problems such as sensor drift. SeaCycler carried an extensively tested gas analyzer: the Pro-Oceanus's CO2-Pro CV, as part of its instrument float. The CO2-Pro CV has shown stable performance during lengthy observations (e.g. Jiang et al., 2014), but has a slow response time for continuous profiling, and its power consumption is not affordable for glider operations. This CO2 optode is an early prototype sensor that has not undergone rigorous testing on a glider, but is compact and uses little power. This paper summarizes the test results for this sensor on a Slocum glider. We capture the performance of the sensor, and for the Labrador Sea mission, comparing the glider data against the SeaCycler's measurements to compute an in-situ correction for the optode. We use the referenced data set to investigate trends in spatial and temporal variability captured by the glider data, pointing to short time and distances scales as drivers of change in this region. [ABSTRACT FROM AUTHOR]

Transport of freshwater from the Labrador Shelf into the interior Labrador Sea has the potential to impact deep convection via its influence on the salinity of surface waters. To examine this transport, the authors deployed two underwater gliders on a mission to traverse the continental shelf break multiple times between 5 July and 22 August 2014, the period when Arctic meltwater has historically peaked in transport down the Labrador Shelf. The field campaign yielded a unique dataset of temperature, salinity, and oxygen across the shelf break to a depth of 1000mat unprecedented spatial resolution. Two mechanisms of cross-shelf transport were examined: Ekman transport and transport due to mesoscale eddies. Ekman transport is quantified using satellite wind stress and near-surface hydrographic properties, and eddy-induced transport is scaled using a parameterized eddy diffusivity and thickness gradients of layers of uniform potential density, as well as the tracer gradients along those isopycnals. Both the Ekman and eddy terms transport high-oxygen and low-salinity water from the shelf to the Labrador Sea during the field campaign. The influence of the eddy-driven oxygen flux fromthe shelf to theLabrador Sea on oxygen budgets depends strongly on the size of the region over which this eddy flux converges. The deduced offshore transport of freshwater (4 ± 6mSv; 1mSv = 103m3 s-1) from both Ekman and eddy mechanisms, which is likely at a seasonal maximum during this summertime survey, represents about 3%of the annual-mean freshwater flowing through Hudson and Davis Straits but may be an important component of the total freshwater budget of the interior Labrador Sea. [ABSTRACT FROM AUTHOR]

Nonlinear barotropic vortical patterns on a -plane are investigated analytically. The solutions describe large-scale Rossby waves rotating anticyclonically with zero circulation. The Rossby waves are predicted to rotate with a specific angular velocity. The stream function-vorticity relation is assumed to be nonlinear, which may lead to a pronounced asymmetry within the pattern. The similarity between the simulated patterns and the Antarctic Circumpolar Wave is highlighted. [ABSTRACT FROM AUTHOR]

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A three-dimensional, baroclinic, finite-volume ocean model (FVCOM) is used to examine hurricane induced responses in Placentia Bay, Newfoundland. Hurricane Igor (2010) and Hurricane Leslie (2012) made landfall within 100 km of the mouth of the bay, with the former to the eastern side and the latter on the western side. The model results have reasonable agreement with field observations on sea level, near-surface currents and sea surface temperature (SST). During landfall the two hurricanes cause the opposite shifts in inner bay circulation. Hurricane Igor overwhelms the mean inflow into the inner bay and shifts the currents to outflow. Hurricane Leslie reinforces the inflow into the inner bay. The peak storm surge is significantly influenced by local wind and air pressure during Leslie, accounting for 34% and 62% at the Argentia and St. Lawrence tide-gauge stations respectively, but predominately due to remote forcing entering the upstream eastern open boundary during Igor. There is a strong near-surface near-inertial response during Leslie, but a weak one during Igor. Stratification plays an important role in both generation and dissipation of near-inertial oscillation. A strong pre-storm stratification during Leslie favours the generation of near-inertia oscillation. Strong turbulent mixing induced on the right side of Leslie generates large vertical movement of the thermocline and thus contributes to strong near-inertia oscillation inside the mixed layer. The barotropic simulation results in a significant underestimation of near-surface currents and near-inertial oscillation. The baroclinic simulation shows a large increase of the current gradient in the vertical, as the first baroclinic mode in response to the hurricane forcing. [ABSTRACT FROM AUTHOR]