Citation: Testor P, Young Bd, Rudnick DL, Glenn S, Hayes D, Lee CM, Pattiaratchi C, Hill K, Heslop E, Turpin V, Alenius P, Barrera C, Barth JA, Beaird N, Bécu G, Bosse A, Bourrin F, Brearley JA, Chao Y, Chen S, Chiggiato J, Coppola L, Crout R, Cummings J, Curry B, Curry R, Davis R, Desai K, DiMarco S, Edwards C, Fielding S, Fer I, Frajka-Williams E, Gildor H, Goni G, Gutierrez D, Haugan P, Hebert D, Heiderich J, Henson S, Heywood K, Hogan P, Houpert L, Huh S, Inall ME, Ishii M, Ito S-i, Itoh S, Jan S, Kaiser J, Karstensen J, Kirkpatrick B, Klymak J, Kohut J, Krahmann G, Krug M, McClatchie S, Marin F, Mauri E, Mehra A, Meredith MP, Meunier T, Miles T, Morell JM, Mortier L, Nicholson S, O’Callaghan J, O’Conchubhair D, Oke P, Pallàs-Sanz E, Palmer M, Park J, Perivoliotis L, Poulain P-M, Perry R, Queste B, Rainville L, Rehm E, Roughan M, Rome N, Ross T, Ruiz S, Saba G, Schaeffer A, Schönau M, Schroeder K, Shimizu Y, Sloyan BM, Smeed D, Snowden D, Song Y, Swart S, Tenreiro M, Thompson A, Tintore J, Todd RE, Toro C, Venables H, Wagawa T, Waterman S, Watlington RA and Wilson D (2021) Corrigendum: OceanGliders: A Component of the Integrated GOOS. Front. Mar. Sci. 8:696100. doi: 10.3389/fmars.2021.696100 Corrigendum: OceanGliders: A Component of the Integrated GOOS

The Wire Flyer towed vehicle is a new platform able to collect high-resolution water column sections. The vehicle is motivated by a desire to effectively capture spatial structures at the submesoscale. The vehicle fills a niche that is not achieved by other existing towed and repeat profiling systems. The Wire Flyer profiles up and down along a ship-towed cable autonomously using controllable wings for propulsion. At ship speeds between 2 and 5 kt (1.02–2.55 m s−1), the vehicle is able to profile over prescribed depth bands down to 1000 m. The vehicle carries sensors for conductivity, temperature, depth, oxygen, turbidity, chlorophyll, pH, and oxidation reduction potential. During normal operations the vehicle is typically commanded to cover vertical regions between 300 and 400 m in height with profiles that repeat at kilometer spacing. The vertical profiling speed can be user specified up to 150 m min−1. The high-density sampling capability at depths below the upper few hundred meters makes the vehicle distinct from other systems. During operations an acoustic modem is used to communicate with the vehicle to provide status information, data samples, and the ability to modify the sampling pattern. This paper provides an overview of the vehicle system, describes its operation, and presents results from several cruises.

Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations.

To address a need for science-based advice on issues of resource exploration, two oceanographic moorings were placed on the abyssal slope of northwest Flemish Cap from July 2013 to July 2014. These yielded some of the first long-term moored measurements of velocity, temperature, and salinity in the region. Hydrographic and lowered-ADCP measurements made during mooring deployment and recovery reveal that the deep Labrador Current flows approximately along isobaths between water depths of 1,200 and 2,200 m. However, these snapshots differ significantly, with stronger currents observed during the deployment survey. The mooring data, obtained near the 1,500 m isobath, reveal a complex temporal variation of the current. The velocity spectrum is dominated by a peak at a period of approximately 21 days, with power increasing with depth in the water column and varying through the year. In other boundary-current studies, variations in the several-week band have been attributed to baroclinic topographic Rossby waves, but with just two widely spaced moorings, we cannot infer the wave number and test for such waves using the dispersion relationship. However, an indirect estimate of wave number can be made by examining the variation of spectral power with depth, and doing this yields results that are reasonably consistent with a linear theory of baroclinic topographic Rossby waves for water of constant stratification over a planar slope. This agreement is somewhat surprising, given the simplicity of the theory and the complexity of the domain, but it appears to offer a clear indication of the importance of baroclinic vorticity dynamics in this region.

Subsurface temperatures in the Slope Water region of the Northwest Atlantic from Argo profiling floats and on the adjacent continental shelf from ship-based measurements are compared with the latitudinal position of the Shelf-Slope Front (SSF) and the Gulf Stream North Wall (GSNW). The Slope Water and shelf temperature anomalies at 200 m depth are in agreement for the period, 2002-2015. For the period 1978-2015, shelf temperatures are significantly correlated with the SSF position, and to a lesser extent with the GSNW position. Annual SSF position anomalies near the Grand Banks at 50 degrees W-55 degrees W lead anomalies to the west at 65 degrees W-75 degrees W by 1-2 years. Wind stress curl is compared with the annual change in the SSF and GSNW latitudinal positions, rather than with the positions directly. Changes in the mean position of the SSF are related to the wind stress curl pattern in the mid-Atlantic, with an 8 month lag. It is suggested that a wind pattern favoring a southward shift of the SSF is associated with a southward shift of the zero-curl line near 40 degrees W, resulting in an expanded subpolar gyre and enhanced flow of Labrador Current Water westward from the Tail of the Grand Banks. However, changes in the GSNW position are related to an NAO-like wind stress curl pattern in the eastern Atlantic in the winter-spring period, in agreement with other studies. High sea surface temperatures in the Gulf of Maine and on the Scotian Shelf in recent years can be largely attributed to positive local onshore wind anomalies.

Fourteen years of data collected by the Atlantic Zone Monitoring Program served to model the habitat of four dominant copepod species (Calanus glacialis, Calanus hyperboreus, Calanus finmarchicus, Paracalanus sp.) on the continental shelf and slope waters in the Northwest Atlantic Ocean. Generalized additive mixed models (GAMMs) were applied to abundance and presence-absence data for C. hyperboreus, C. glacialis and Paracalanus sp. and abundance for C. finmarchicus, to describe the optimal environmental productivity envelopes associated with the occurrence and/or the net productivity of these species. The models for Calanus species considered two main phases of their life cycle: (i) an active population growth phase dominated by early stages that occur primarily in surface layers, and (ii) a dormant phase dominated by overwintering stages generally found in deeper layers. GAMMs identified a marked contrast in environmental envelopes occupied by arctic and temperate species. Our analyses underline the importance of using data representative of all the copepodid developmental stages and occupied habitats in order to accurately model the distribution of Calanus species. The value of our models as tools to understand past events in the Northwest Atlantic or to predict future distributions of the species is also discussed.

We report on our analysis of zooplankton community structure in the western North Atlantic based on spring and fall monitoring surveys from 1999 to 2011 of three large marine ecosystems (LMEs; Newfoundland Shelf, Gulf of St. Lawrence and Scotian Shelf). We aimed to synthesize knowledge of the distribution of zooplankton communities and to evaluate their relationship to environmental conditions as either biogeographic constraints or smaller-scale ecosystems drivers or both. A combination of exploratory and constrained analyses helped identify the dominant roles of bathymetry, surface salinity and temperature, subsurface biogeochemical inventories of nitrate and chlorophyll a on the macroscale distribution of zooplankton. These variables highlight the potential influences of vertical habitat features, latitudinal and estuary-ocean gradients, deep-water intrusions, and differences in the seasonal succession on community structure at biogeographic scales. The spatial pattern in the residual field of the constrained analysis suggests that mesoscale features may play a role in shaping community structure within each of the LMEs and point to the limitation of analytical approaches based principally on water mass tracers applied over broad-scales. Interannual variations in key environmental drivers had inconsistent abilities in predicting changes in community composition across LMEs. Organisms that had the greatest influence on the delineation of communities were similar between spring and fall surveys and consisted of roughly a dozen dominant and ubiquitous taxa. Determining the influence of environmental variations on productivity of key secondary producers requires an approach focussed at the scale of individual LMEs in order to address the consequence of dissimilarities in the dominant trophic relationships or the response to remote forcing across the region. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.

We review opportunities, impediments, regional scope and principles for a Canadian contribution to an Integrated Atlantic Ocean Observing System (IAOOS) in the context of the Galway Alliance. This contribution should build on what exists, plan ahead for data management and data access, be flexible and sustainable, encourage international involvement, be science-led, foster research aggregation, and have close links to remote sensing, data assimilation and prediction programs. Existing programs that can contribute are described, and new initiatives that will broaden relevance of the Observing System are identified, including biological/ ecosystem observations. Specific platforms and technologies for both near-shore and offshore waters are listed, together with areas where new developments are needed. Finally, we outline a strategy for the development of an Atlantic Canada Regional Ocean Observing System (ACROOS).

The structure and variability of the wintertime midshelf front in the New York Bight is examined using moored observations of currents and hydrography during 2007. The front is located near the 50 m isobath, inshore of the shelf break front and offshore of estuarine outflow plume fronts. It spans the water column and is the boundary between cooler, fresher, and less dense inner shelf water and warmer, saltier, and denser outer shelf water. The mean hydrographic front slopes upward offshore, and there is an associated equatorward along‐shelf 5–10 cm/s surface‐intensified current jet. The mean across‐shelf circulation is offshore near the surface and onshore at depth. The across‐shelf velocity is convergent and strengthens across‐shelf property gradients with a time scale for gradient doubling of approximately 8 days. Tidal analysis of currents and temperatures suggests that tidal shear dispersion is not an important mechanism for midshelf front formation. The frontal structure and location are roughly consistent with the theory of bottom boundary layer advected fronts, suggesting that multiple estuarine outflows are collectively responsible. Pulses of strong offshore wind cause the breakdown of the across‐shelf thermal wind balance, which has been commonly assumed to hold in shelf environments. Observed shear significantly exceeds thermal wind shear at middepths, where observation of low‐gradient Richardson number indicates the importance of vertical mixing. The response of currents to wind fluctuations is asymmetric, whereby the combination of upwelling favorable and offshore winds or downwelling favorable and onshore winds produces a stronger response than winds from the remaining quadrants.

Geostrophic adjustment of an isolated axisymmetric lens was examined to better understand the dependence of radial displacements and the adjusted velocity on the Burger number and the geometry of initial conditions. The behavior of the adjustment was examined using laboratory experiments and numerical simulations, which were in turn compared to published analytical solutions. Three defining length scales of the initial conditions were used to distinguish between various asymptotic behaviors for large and small Burger numbers: the Rossby radius of deformation, the horizontal length scale of the initial density defect, and the horizontal length scale of the initial pressure gradient. Numerical simulations for the fully nonlinear time-dependent adjustment agreed both qualitatively and quantitatively with analogous analytical solutions. For large Burger numbers, similar agreement was found in laboratory experiments. Results show that a broad range of final states can result from different initial geometries, depending on the values of the relevant length scales and the Burger number computed from initial conditions. For Burger numbers much larger or smaller than unity, differences between different initial geometries can readily exceed an order of magnitude for both displacement and velocity.

Efficiently profilingthe water column to achieve both high vertical andhorizontalresolutionfrom a moving vessel in deep water is difficult. Current solutions, such as CTD tow-yos, moving vessel profilers, and undulating tow bodies, are limited by ship speed or water depth. As a consequence, it is difficult to obtain oceanographic sections with sufficient resolution to identify many relevant scales over the deeper sections of the water column. This paper presents a new concept for a profiling vehicle that slides up and down a towed wire in a controlled manner using the lift created by wing foils. The wings provide a novel low-power method of propulsion along the cable by using the free stream velocity of the wire moving through the water in similar fashion to a sailboat sailing up wind. Scale model tests show a wide range of achievable profiling glide slopes for tow cable angles between vertical and 458, and effective isolation of cable strum vibration from the towed vehiclebody.Theconceptisnotdepthlimitedandwilloffertwo-dimensionalresolutionthatmeetsorexceeds current undulating tow bodies over the full water column. Additionally, this system could be used simultaneously with many other deep towed instrument packages to produce complementary datasets.

We develop and test a method to observationally estimate lateral intrusive heat flux across a front. The model combines that of Joyce (1977), in which lateral cross-frontal advection by intrusions creates vertical temperature gradients, and Osborn and Cox (1972) in which vertical mixing of those gradients creates thermal microstructure that is dissipated by molecular conduction of heat. Observations of thermal microstructure dissipation chi(T) are then used to estimate the production by intrusions, and hence the lateral heat flux and diffusivity. This method does not depend on the precise mechanism(s) of mixing, or on the dynamical mechanisms driving the frontal intrusions. It relies on several assumptions: (1) lateral cross-frontal advection produces diapycnal temperature gradients that are mixed locally, (2) thermal variance is dissipated locally and not exported, (3) intrusion scales are larger than turbulence scales, and (4) isotropy of temperature microstructure is assumed in order to estimate chi(T).The method is tested using microstructure observations in Meddy "Sharon," where the erosion rate and associated lateral heat flux are known from successive mesoscale hydrographic observations (Hebert et al., 1990). An expression is developed for the production (lateral heat flux times lateral temperature gradient, expected to equal chi(T)) in a front of steady shape that is eroding (detraining) at a steady rate; the production is proportional to the erosion speed and the square of the cross-frontal temperature contrast, both of which are well-known from observations. The qualitative structure and integrated value of the dissipation agree well with model assumptions and predictions: thermal variance produced by lateral intrusive heat flux is dissipated locally, dissipation in intrusive regions dominates total dissipation, and the total dissipation agrees with the observed erosion rate, all of which suggests that microstructure observations can be used to estimate intrusive heat flux. A direct comparison was made between lateral heat flux estimated from mesoscale Meddy structure plus the known rate of erosion, and lateral flux based on microscale temperature dissipation, with excellent agreement in the frontal zone and poorer agreement where lateral temperature gradient is too small to accurately measure.

Laboratory experiments in a rotating, continuously stratified fluid were used to examine the problem of lateral dispersion by the relaxation of diapycnal mixing events. Localized mixing was imposed mechanically to create isolated mixed patches, which were subsequently allowed to adjust under the influence of rotation to spin up balanced eddies. The effect of the superposition of many such eddies on lateral dispersion was quantified via the rate of spreading of a passive tracer released into the flow. Results indicate that the rate of lateral dispersion is approximately inversely proportional to the time between mixing events, and that it depends strongly on both rotation rate and buoyancy frequency of the ambient fluid through the Rossby radius of deformation and the Burger number. The importance of these parameters is consistent with theoretical predictions and numerical simulations of lateral dispersion for the same mechanism as described by previous investigators. However, the particular dependence found in the present laboratory experiments for Bu > 1 suggests a modified scaling that takes into account the finite scale of the initial mixed patches.

We present the observations from a pair of field experiments at the New England shelfbreak front in June and August of 2002, each consisting of 14 cross-frontal surveys using the Lamont Pumping SeaSoar. Measurements of the front's physical, chemical, and bio-optical characteristics were made at high spatial and temporal resolution. The front. based on water-column hydrographic distributions, was found within a few km of the 200 m isobath during both cruises. We present here composite sections, based on averages of individual sections shifted in space to a common frontal location, of the cross-frontal distributions of these properties as a measure of the mean state of the front in both June and August. The observations show the familiar temperature, salinity, and density distributions of the summertime front, dominated by surface thermal heating. Nutrient and bio-optical distributions show the combined effects of water-mass exchange and biological processes. T, S, silicate, and phosphate distributions are suggestive of cross-frontal exchange of slope- and shelf waters, although transport mechanisms and pathways are not apparent. These properties, along with nitrate and optical measures of the suspended particle distributions, show vertical displacements of isopleths as the front is approached: property contours slope upwards toward the front from the shoreward side, and downwards toward the front from the seaward side. Again, actual water-movement pathways are not constrained by these suggestive patterns. Bio-optical distributions show elevated indicators of photosynthetic efficiency both seaward and shoreward of the front, but the front itself is a minimum in biomass. Accumulation of photosynthetic biomass appears to be controlled primarily by nitrate scarcity in waters within and above the pycnocline. At the base of the pycnocline, light limitation appears to be the controlling factor, although the base of the euphotic zone is deeper than the biomass maxima and the base of the pycnocline. Mechanisms explaining this phenomenon are unclear, but tenuous evidence suggests low stratification at the depth of the 1% light level may not allow phytoplankton to optimize for the low-light, high-nutrient conditions at depth. Cross-frontal differences in nutrient and bio-optical parameters, particularly in August, suggest distinct phytoplankton assemblages, and the presence of calcite-forming or nitrogen fixing groups to the community structure, especially in very shallow waters across the front and in pycnocline waters seaward of the front. (C) 2009 Elsevier B.V. All rights reserved.

We present observations from deployments of a microstructure turbulence instrument (the Towed Microstructure and Auxiliary Sensor Instrument) aboard a pumping profiling vehicle (the Lamont Pumping SeaSoar) towed behind a research vessel at the New England shelf break front in August 2002. From these we determined coincident fine‐scale vertical eddy diffusivity and gradients of nitrate, phosphate, and silicate on several transects spanning the front. We then quantified vertical turbulent nutrient fluxes through the base of the euphotic zone (defined as the 1% light level), the base of the density transition zone, maximum nutrient gradients (the nutriclines), and the depth of maximum stratification (the pycnocline). Vertical eddy diffusivity estimates spanned a wide range from near‐molecular levels at the pycnocline to values exceeding 10 −3 m 2 s −1 at depth and in the surface layers. Vertical nutrient fluxes were maximal at the 1% light level and decreased by 2 orders of magnitude as they moved upward through the water column to the depth of the pycnocline. Nutrient fluxes were enhanced shoreward of the front because of high mixing rates and nutrient gradients at the depth of the 1% light level. Nitrate fluxes there averaged about 6 × 10 −5 mmol N m −2 s −1 , sufficient to support a net community productivity of 30 mmol C m −2 d −1 . Seaward of the front, these fluxes averaged about 1 × 10 −5 mmol N m −2 s −1 and would support correspondingly lower productivity. A small part of the upward flux appeared to support a silicifying community of phytoplankton that consumed phosphate in proportion to nitrate at about double the canonical Redfield stoichiometry.