Blair J.W. Greenan

Fisheries and Oceans Canada | DFO · Bedford Institute of Oceanography

Biogeochemical- (BGC-) Argo aims to deploy and maintain a global array of autonomous profiling floats to monitor ocean biogeochemistry. With over 250,000 profiles collected so far, the BGC-Argo network is rapidly expanding toward the target of a sustained fleet of 1,000 floats. These floats prioritize the measurement of six key properties: oxygen,...

Have you ever wondered how scientists know what is happening deep below the surface of the ocean? There are several types of robots that can dive below the sea surface and bring back data from underwater. One type of robot, called an Argo float, moves through the middle depths of the ocean with the currents and comes to the surface once every 10 da...

Climate change affects virtually all marine life and is increasingly a dominant concern for fisheries, reinforcing the need to incorporate climate variability and change when managing fish stocks. Canada is expected to experience widespread climate-driven impacts on its fisheries but does not yet have a clear adaptation strategy. Here, we provide a...

In the past two decades, the Argo Program has collected, processed, and distributed over two million vertical profiles of temperature and salinity from the upper two kilometers of the global ocean. A similar number of subsurface velocity observations near 1,000 dbar have also been collected. This paper recounts the history of the global Argo Progra...

Climate change impacts on fisheries will undoubtedly have socio-economic impacts on coastal communities and the seafood market. However, it is a challenge to integrate climate change information in a form that can be used efficiently by adaptation planners, policy makers, and fishery managers. In this study, we frame a climate change impact assessm...

A storm surge hindcast for the west coast of Canada was generated for the period 1980–2016 using a 2D nonlinear barotropic Princeton Ocean Model forced by hourly Climate Forecast System Reanalysis wind and sea level pressure. Validation of the modeled storm surges using tide gauge records has indicated that there are extensive areas of the British...

The Argo Program has been implemented and sustained for almost two decades, as a global array of about 4000 profiling floats. Argo provides continuous observations of ocean temperature and salinity versus pressure, from the sea surface to 2000 dbar. The successful installation of the Argo array and its innovative data management system arose opport...

The Argo Program has been implemented and sustained for almost two decades, as a global array of about 4000 profiling floats. Argo provides continuous observations of ocean temperature and salinity versus pressure, from the sea surface to 2000 dbar. The successful installation of the Argo array and its innovative data management system arose opport...

A 1/12 degree North Atlantic model is used to investigate the Atlantic Meridional Overturning Circulation (AMOC) variability from 1990 to 2015. The seasonality of the AMOC in depth and density spaces is dominated by the Ekman transport from low to high latitudes. At interannual timescales, the AMOC in depth and density spaces has different characte...

This chapter describes physical and chemical changes in the oceans surrounding Canada on decadal and longer time scales, and discusses these changes in the context of anthropogenic climate change and natural climate variability.

An array of overturning data The Atlantic meridional overturning circulation (AMOC) has a strong influence on climate, so it is important to understand how global warming may affect it. Lozier et al. report initial results from the Overturning in the Subpolar North Atlantic Program (OSNAP) (see the Perspective by Rhein). OSNAP has been measuring th...

The potential benefits of using a geometric mean method for computing a vulnerability index are presented using both simulated variables as well as data from a Canadian coastal geodatabase (CanCoast). The assessment of vulnerability of natural and built coastal infrastructure to sea level rise is used to demonstrate the advantages of this method fo...

The understanding of the seasonal variability of carbon cycling on the Scotian Shelf in the NW Atlantic Ocean has improved in recent years; however, very little information is available regarding its short-term variability. In order to shed light on this aspect of carbon cycling on the Scotian Shelf we investigate the effects of Hurricane Arthur, w...

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...

The understanding of seasonal variability of carbon cycling on the Scotian Shelf, NW Atlantic Ocean, has improved in recent years, however, very little information is available regarding its short-term variability. In order to shed light on this aspect of carbon cycling on the Scotian Shelf we investigate the effects of Hurricane Arthur, which pass...

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...

For decades oceanographers have understood the Atlantic meridional overturning circulation (AMOC) to be primarily driven by changes in the production of deep-water formation in the subpolar and subarctic North Atlantic. Indeed, current Intergovernmental Panel on Climate Change (IPCC) projections of an AMOC slowdown in the twenty-first century based...

For decades oceanographers have understood the Atlantic meridional overturning circulation (AMOC) to be primarily driven by changes in the production of deep-water formation in the subpolar and subarctic North Atlantic. Indeed, current Intergovernmental Panel on Climate Change (IPCC) projections of an AMOC slowdown in the twenty-first century based...

Acoustic Doppler Current Profilers and underwater gliders were simultaneously deployed as part of the Ocean Tracking Network to continuously monitor the Halifax Line (HL) and the Nova Scotia Current (NSC) between 2008 and 2014. The HL transects the Scotian Shelf, which connects dynamically important areas, such as the Grand Banks, the Gulf of Maine...

The behavior of the Labrador Current during the period from 1990 to 2007 is investigated with an eddy-resolving circulation model for the North Atlantic Ocean. An EOF analysis of the model output suggests that the variability in the Labrador Current can be partitioned into a western Labrador Current (WLC; from the 300-2500 m isobaths), and an easte...

Repeated glider transects across the Scotian Shelf (Eastern Canadian Seaboard) completed between 2011 and 2015 provide a dataset with high temporal and spatial resolutions. This new dataset is used to characterize the seasonal variability of the Nova Scotia Current (NSC): a southwestward, coastally-trapped, alongshore current flowing from the Gulf...

Sea-level allowances at 22 tide-gauge sites along the east coast of Canada are determined based on projections of regional sea-level rise for the Representative Concentration Pathway 8.5 (RCP8.5) from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) and on the statistics of historical tides and storm surges (s...

The Ross Sea sustains a rich ecosystem and is the most productive sector of the Southern Ocean. Most of this production occurs within a polynya during the November–February period, when the availability of dissolved iron (dFe) is thought to exert the major control on phytoplankton growth. Here we combine new data on the distribution of dFe, high-re...

This paper documents the methodology of computing sea-level rise allowances for Atlantic Canada in the 21st century under conditions of uncertain sea-level rise. The sea-level rise allowances are defined as the amount by which an asset needs to be raised in order to maintain the same likelihood of future flooding events as that site has experienced...

The layered structure of stratification and mixing on the New England Shelf (NES) in summer is examined by analyzing a comprehensive set of observations of hydrography, currents and turbulence. A clear distinction in mixing characteristics between the mid-column water (consisting of sub-surface stratification, mid-depth weak stratification and lowe...

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 involvemen...

Understanding nearshore migration of Atlantic Salmon is a key to further improve management and conservation of this species. While monitoring migration remains a challenge, the rapid development of fish tracking techniques and fixed listening arrays leads to unprecedented opportunities to map migration routes and measure their spatial and temporal...

The Sable Gully, a broad, shelf break submarine canyon approximately 40 km east of Sable Island on the eastern Scotian Shelf, separates Banquereau and Sable Island Banks. Unique among canyons on the eastern Canadian continental shelf because of its depth, steep slopes and extension far onto the shelf, its ecological significance and increasing huma...

Abstract The model results from 1990 to 2012 are presented for the Newfoundland Shelf and adjacent ocean in order to help better understand physical oceanographic conditions in the region. The model used in this report is a 1/12 degree North Atlantic model developed at Bedford Institute of Oceanography. The model is driven by CORE (Common Ocean-ice...

The Sable Gully is a broad deep underwater canyon located to the east of Sable Island on the edge of the Scotian Shelf. Being the home of many marine species including the endangered Northern Bottlenose Whale, the Gully was designated as a marine protected area (MPA) in 2004. Better understanding of physical environmental conditions over this MPA i...

Three midwater-trawl surveys of the nekton and micronekton at meso- and bathypelagic depths in The Gully, a submarine canyon and Marine Protected Area immediately east of Sable Island, were conducted in August / September 2008, August 2009 and March 2010 respectively. The surveys were designed to gather data on fish, cephalopods and crustaceans but...

Instrumented, subsurface moorings deployed in the Scotian shelf and slope regions of the North Atlantic provide data in low to moderate flows for a current meter intercomparison. The primary instruments being evaluated are two acoustic Doppler single-point current meters, the Aanderaa Seaguard (SG) and the Teledyne RD Instruments (RDI) Doppler volu...

Phytoplankton plays a critical role in the uptake of atmospheric carbon dioxide by the ocean, and is comprised of a spectrum of cell sizes that are strongly associated with different oceanographic conditions. Studies suggest that the ocean will become increasingly stratified in response to a warming climate, limiting nutrient exchange to the upper...

To investigate the processes by which sediment is transported through a submarine canyon incised in a glaciated margin, the bottom boundary layer quadrapod RALPH was deployed at 276-m depth in the West Halibut Canyon (off Newfoundland) during winter 2008–2009. Two main sediment transport processes were identified throughout the deployment. Firstly,...

Much of the variability in the surface ocean's carbon cycle can be attributed to the availability of sunlight, through processes such as surface heat flux and photosynthesis, which regulate carbon flux over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and m...

The short, but intense spring bloom, occurring late March to early April on the Scotian Shelf in the northwest Atlantic draws down approximately 50% of the total carbon fixed over the annual cycle in this region. In the spring and summer months following the collapse of the bloom, nutrient and chlorophyll levels plummet suggesting that further draw...

The Sable Gully is the largest submarine canyon along the shelf break off the east coast of North America. The circulation and hydrography in the Gully have significant temporal and spatial variability. This paper presents a numerical study of the three-dimensional circulation and hydrography in the Gully using a multi-nested ocean circulation mode...

Much of the variability in the surface ocean's car-bon cycle can be attributed to the availability of sunlight, trig-gering surface heat flux and photosynthesis, which in turn regulate the biogeochemical cycling of carbon over a wide range of time scales. The critical processes of this carbon cy-cle regulation, occurring at time scales of a day or...

Since 2008, operations to deploy an “acoustic curtain” of hydrophone receivers along the Halifax Line on the Scotian Shelf have been carried out as part of the Ocean Tracking Network research project. Preliminary results of acoustic tag detections by the hydrophones suggested that marine species cross the Halifax Line away from the Nova Scotian Cur...

Much of the surface ocean carbon cycle variability can be attributed to the availability of sunlight, through processes such as heat fluxes or photosynthesis, which regulate the ocean carbon cycle over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and most o...

Much of the variability in the surface ocean's carbon cycle can be attributed to the availability of sunlight, through processes such as heat fluxes and photosynthesis, which regulate over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and most of these have...

Quantitative descriptions and interpretations of currents over the Atlantic Canadian slope for applications to oil and gas (and other) issues

Tidal oscillations dominate the flow field in many submarine canyons. Observations have shown that semidiurnal tidal energy in submarine canyons is significantly amplified with respect to adjacent shelves. This amplification is thought to be caused by focusing of propagating internal tides incident from the open ocean, or local in-canyon generation...

The Labrador Sea experienced very warm winter surface air temperatures in 2010 similar to the previous year; temperatures ranged from approximately 10°C above normal in the northern region near Davis Strait to about 5°C above normal in the southern Labrador Sea. Sea surface temperature anomaly was more than 2°C in the Labrador Sea throughout the wh...

The seasonal variability of inorganic carbon in the surface waters of the Scotian Shelf region of the Canadian northwestern Atlantic Ocean is investigated. Seasonal variability is assessed using hourly measurements covering a full annual cycle of the partial pressure of CO2, (pCO2), and hydrographic variables obtained by an autonomous moored instru...

The coastal oceans have relatively large fluxes of CO2, but the temporal variability of these systems is high. Compared to open ocean systems, the variability of the CO2 system in coastal regions remains poorly understood. The Scotian Shelf is a highly productive area of the Canadian northwestern Atlantic Ocean. The region is host to active fisheri...

The Labrador Sea experienced very warm winter surface air temperatures in 2009; temperatures ranged from approximately 8°C above normal in the northern region near Davis Strait to about 2-4°C above normal in the southern Labrador Sea. This is in strong contrast to the 2008 winter conditions during which the central Labrador Sea experienced the cold...

The development of seismic oceanography requires direct comparison of seismic data to high-resolution oceanographic measurements over long horizontal scales. Here, we compare multichannel seismic (MCS) reflection images to 300 km of spatially-coincident, high-resolution (<1 km) expendable bathythermograph (XBT) surveys that were collected near a fr...

The spring bloom on the Scotian Shelf is examined using a mooring array deployed from 18 March 2002 to 18 April 2002 to provide physical, chemical, and biological measurements with high temporal and vertical resolution. These measurements are complemented by the Atlantic Zone Monitoring Program (AZMP) biweekly occupations of a station near the moor...

Measurements of stratification and shear were carried out as part of the EDDIES tracer release experiment in mode-water eddy A4 during the summer of 2005. These measurements were accomplished using both shipboard instrumentation and a drifting mooring. A strong relationship between shear intensity and distance from the center of the eddy A4 was obs...

Evidence is presented that lateral dispersion on scales of 1–10 km in the stratified waters of the continental shelf may be significantly enhanced by stirring by small-scale geostrophic motions caused by patches of mixed fluid adjusting in the aftermath of diapycnal mixing events. Dye-release experiments conducted during the recent Coastal Mixing a...

During the Coastal Mixing and Optics Experiment in 1996 and 1997, an integrated dye and microstructure experiment was done to measure and compare mixing rates on the continental shelf. The results of the dye experiment are presented in the companion paper by Ledwell et al. [2004]. In this paper, we explore the results from microstructure measuremen...

Physical, chemical and biological data from the Scotian Shelf indicate that short-term physical events affect the dynamics of spring and fall blooms. This is based on results from a three-week mooring deployment measuring currents, temperature, salinity and fluorescence in October 2000, combined with biweekly sampling of temperature, salinity, nutr...

The traditional view of the production cycle on the continental shelf of Nova Scotia features a spring bloom followed by a period of low production and a less intense fall bloom. The annual cycle of primary productivity thus has a large, low frequency component. However, there is increasing evidence that the production cycle has significant variabi...

Some recent measurements of the mixed layer in oceans and lakes have indicated that the rate of the dissipation of turbulent kinetic energy, ε, is much higher than expected from a purely shear-driven wall layer. This enhancement has usually been attributed to wave breaking. In this study, measurements of dissipation in the open-ocean mixed layer on...

A tethered free-fall microstructure glider, designed to make quasi-horizontal profiles of the ocean mixed layer, was tested at Emerald Bank on the Scotian Shelf in June 1996. The vehicle attained a 4:1 gliding ratio with the angle of attack close to 0°. The glider typically stabilized its pitch and roll within the first 10 s of each flight. The veh...

Anemometer‐measured winds for the period 5–13 March 1994 were used to study the coherence of observed and forecast coastal winds along the mid‐Labrador shelf. The reliability of these variables in predicting the response of the ocean and ice to wind forcing is an important issue for ice forecasting in this area. Two anemometer‐equipped 2‐m ice beac...

A tethered free-fall microstructure glider was designed to make quasi-horizontal profiles of the ocean mixed layer. Glider tests were carried out at Emerald Bank on the Scotian Shelf in June 1996. The vehicle attained a 4:1 gliding angle with the angle of attack close to 0°. The glider typically stabilized its pitch and roll within the first 20 sec...

Forecast ice drift rates and thicknesses displayed on daily ice charts and forecast winds for the Canadian east coast are compared to on‐ice observations made during the second Canadian Atlantic Storm Program (CASP II) of March 1992. Observed and 24‐hour forecasts of daily ice drift rates were weakly correlated even though long‐term means closely m...

Hailstone growth experiments were performed in a vertical icing wind tunnel using 2-cm oblate ice spheroids (axis ratio of 0.67) mounted on a gyrator system. The liquid water content ranged from 1 to 5 g m3, air temperature from 21° to 3°C, air speed from 9 to 24 m s1, and air pressure from 40 to 100 kPa. Icing time, ice and water mass of the hails...

Simultaneous measurements of surface temperatures in the equatorial and polar regions of gyrating hailstones, growing in a closed circuit wind tunnel, were performed using two infrared microscopes. Results indicate that a temperature difference as high as 5.9°C existed between these regions, with maximum differences occurring in the liquid water co...

Results of experiments performed in an icing tunnel demonstrate, for the first time, that existing theory accurately describes the heat and mass transfer of individual hailstones growing in a supercooled cloud. The experiments were carried out using spheroidal ice models with a major axis diameter of 2 cm and aspect ratio of 0.67. In previous hail...

Remote infrared measurements of equator and pole temperatures of rotating spherical and gyrating spheroidal hailstones during growth in an icing tunnel demonstrate that the surface temperatures are not isotropic and homogeneous as has always been assumed. The temperature differences are measured to be as large as 6°C for spheres and 4°C for spheroi...

This report presents a brief summary of papers describing physical oceanographic research undertaken in Canada in the period 2003 to early 2007. This report is part of the Canadian contribution to the International Association for the Physical Sciences of the Ocean (IAPSO) on the occasion of the meeting of the Interannual Association of Geodesy and...