Recent posts

New paper: “Cross-slope flow in the Atlantic Inflow Current driven by the on-shelf deflection of a slope current”

Highlights

  • Slope water has been tracked on the European Shelf using drifters and gliders.
  • The deflection onto the shelf is not captured in models.
  • The slope water has a higher nitrate concentration that the shelf water, and supplies nutrients to the shelf.
untitled
(a) pathway of the shallow drifters over the first 45 days after their release, in grey. The thick black trajectory shows the time mean line, from which the local across and along flow directions are derived. The local bathymetry is shown by thin black lines and Coriolis parameter/depth (f/h) contours by dashed lines. Location A is the point at which the shallow drifters stagnated and turned to cross f/h contours.  (b) The trajectories of all of the drifters throughout their active periods, shaded by the date. Location C shows the drifter release point, Location D shows where the deeper drifters crossed onto the shelf and Location B where the deeper drifters re-joined the slope.

 

Porter, M., Dale, A., Jones, S.C., Siemering, B., Inall, M.E. (2018). Cross-slope flow in the Atlantic Inflow Current driven by the on shelf deflection of a slope current. Deep-Sea Research Part I, in press.  doi:10.1016/j.dsr.2018.09.002

Advertisements

New paper published: “Decadal variability on the Northwest European continental shelf”

Jones, S., Cottier, F., Inall, M., & Griffiths, C. (2018). Decadal variability on the Northwest European continental shelf. Progress in Oceanography, doi: 10.1016/j.pocean.2018.01.012

https://doi.org/10.1016/j.pocean.2018.01.012

This paper details one of the key outcomes from my PhD so it was good to get it finished!  It describes how wind acting over the shallow seas west of Scotland can change the origin of waters on the inner continental shelf (and the coast).  This region typically recieves a mix of salty, nutrient rich water from the Atlantic and fresher, relatively nutrient poor water from the Irish Sea.  1-2 months of sustained easterly winds can block the inflow of Atlantic water and drive a pulse of Irish Sea water into the region, potentially importing much greater abundances of Irish Sea organisms and pollutants than during a typical year.  This body of water is detectable on the continental shelf for several months before it it fully displaced northwards.  Conversely, sustained winter storms can drive Atlantic water far onto the shelf and block the outflow from the Irish Sea, bringing oceanic conditions to what would normally be considered coastal locations.  The strong variability which results is roughly an order of magnitude greater than the changes seen in the adjacent Northeast Atlantic so is thought to mask the well documented decadal changes in these waters.

maps_comb1
Map of waters off western Scotland.  Black rectangles show the position of Ellett Line stations on the continental shelf.
plot5 effort 1
Time series of surface salinity from Ellett Line stations on the continental shelf.  x-axis depicts longitude, between the shelf edge (left) and the Scottish coastline (right). (a) shows surface salinity, where brown colours indicate high salinity oceanic water and blue shows lower salinity coastal water. (b) shows the mean salinity across the shelf for each year.  (c) shows the salinity anomaly calculated by subtracting the mean of each station from the data, and (d) depicts the mean surface salinity for each station.  The grey region gives the standard deviation of the data which is a measure of the variability present.

Winning video and overall competition winning entry – ARCHeR

My animation of FVCOM model output won the 2017 ARCHeR image and video competition.  ARCHeR is the largest Cray supercomputer in the UK, and its supercomputing service was used by Dr Dmitry  Aleynik (SAMS) to run a series of simulations of waters off the west coast of Scotland.  I used the output of these model runs to create the animation using Paraview.

comp_screenshot

Link to the ARCHeR competition gallery here.

Learn more about my work on data visualisation here.

References:

1 Aleynik, D. Davidson, K., Dale A. C., Porter, M. (2016) A high resolution hydrodynamic model system suitable for novel harmful algal bloom modelling in areas of complex coastline and topography. Harmful Algae, 53(3):102–117, 10.1016/j.hal.2015.11.012

 

SAMS Magical Mystery Tour… part 1

There are numerous projects and facilities within SAMS that are a mystery to many staff outside specific departments. I thought it might be nice to have an occasional informal show-and-tell with a general staff invite, whether it be an interesting experiment, piece of equipment or entire enigmatic wings of the building.

For a start, Professor Mark Inall kindly offered to do a demonstration of the fjord tank .

We had a great turnout, with two sittings to accomodate everyone. Based on the success of this session we’ll definitely do another one fairly soon. A couple of photos below showcasing the tank and Mark’s smashed finger!

Open day at the SAMS Ocean Explorer Centre

On the weekend of the 27/28th SAMS organised a series of outreach and public engagement activities. I set up an exhibition based on the SAMS Marine Robotics Facility, and featuring several of our underwater vehicles. It’s rare that the public gets to see the robots in the flesh, so it was nice to show them off and answer a range of interesting questions.

A couple of photos courtesy of Raeanne.

IMG_1491
Showing off the SAMS underwater robotics cabability at the OEC open day, May 2017
IMG_1490
Showing off the SAMS underwater robotics cabability at the OEC open day, May 2017

Hydrofoil surfboard

I thought I would share some pictures of a recent project to build a hydrofoil for a kitesurf board.  Public awareness of hydrofoils has increased since their adoption by Americas Cup catamarans but very simply they are just a wing which is designed to lift in water.  For this project, the aim is to generate enough lift to raise the board and rider out of the water, allowing a completely smooth and almost frictionless ride.  This means that you can kitesurf in very light winds at up to 3 times the windspeed.  Kite foilboards are increasingly being used for racing, but my interest was more in its freeride potential for exploring the flat waters around Oban.

I decided to modify a kite surfboard to suit the foil, but wanted to retain the ability to remove the foil and use it as a regular board when the conditions suited.  Consequently the foil is mounted using a strong carbon plate attached to the board by 4 bolts.  To spread the load a little more, a glass-fibre plate is also mounted top and bottom.

The forces through the vertical mast are huge, so for this version I bought a pre-made aluminium mast online.  The baseplate and wings bolt on to this.  I thought this modular approach might come in handy if I decide to build higher performance wings at some point.

As of writing this article I’ve had six sessions with the board and am now reasonably confident at flying it on both tacks.  The initial learning curve is very steep and involves a lot of crashes, but it’s been worth the effort.  When you get up on the foil the feeling must be similar to a seabird skimming the surface; completely smooth and silent.  It’s also very clear that you’re flying a tiny, sensitive airplane through the water, and the muscle memory to control the height takes some getting used to.  But it’s very addictive!

Edit: Now have a short clip of it in action: https://www.youtube.com/watch?v=VLkVU4_AP7M

 

Boat sketching…

I was asked to come up with a sketch of a hypothetical coastal vessel which might one day replace Calanus at SAMS.  The result was a multihull, loosely based on the RV Princess Royal.  It’s deploying a glider for added scientific relevance!  Pen and watercolour.

sams_coastal_vessel_3

New paper published: “Carbon exchange between a shelf sea and the ocean: The Hebrides Shelf, west of Scotland”

Our paper based on the findings from an oceanographic cruise: “DY017” in November 2014 is available through Open Access here.  This was one of Discovery’s early voyages and so much of the cruise was spent ironing out bugs in the ship’s systems.  In addition the weather, as might be expected for the time of year, was inclement.  Nonetheless, we completed several transects of the shelf edge and managed to collect enough data to estimate the carbon and nutrient fluxes between the shallow continental shelf and the deep ocean.  We found that the Hebrides shelf exports 3-5 times the global mean of Particulate Organic Carbon (POC) through downwelling circulation which is typical of the region.  This could represent 1% of the total global downslope POC export, and means that the Hebrides shelf is likely to be a significant source of POC for the northeast Atlantic Ocean.

SSB_paper

Contoured section plots for each transect of dissolved inorganic carbon (DIC), particulate organic carbon (POC), particulate organic nitrogen (PON), particulate organic phosphorus (POP), and biogenic silica (bSi).