GROOM Trieste 2013

Cutting edge Science and Research from

a Glider Base in the North Atlantic

by

Toby Sherwin, Mark Inall, Estelle Dumont and Dima Aleynik

Scottish Association of Marine Science (SAMS)

GROOM Trieste 2013

SAMS

Local test sites

West coast of ScotlandEasy access to sheltered deep water and the North

Atlantic

Loch Linnhe (200m)

Ardmucknish Bay (30m)

Loch Etive (140m)

10 km

North Atlantic launch point

GROOM Trieste 2013

ONGOING WORK

The Ellett Line(Gliders providing better monitoring and novel

science)

GROOM Trieste 2013

The Rockall Trough and Ellett Line

ENAW – Eastern North Atlantic WaterWTOW – Wyville Thomson Ridge Overflow WaterLSW – Labrador Sea WaterAABW – Antarctic Bottom Water

?

?

GROOM Trieste 2013

60 years of θ and S in the Rockall Trough

from: Sherwin, Read, Holliday and Johnson (2012) ICES Journal of Marine Science; doi:10.1093/icesjms/fsr185

OWS surface readings

RRS full depth readings

(HADSST surface temps)

Glider readings

+ winter top 4 m● winter top 800 m

GROOM Trieste 2013

Glider observations

• Mission 1: winter 2009/2010 Rockall Trough• Mission 2: summer 2011 Scotland to

Iceland• Next Mission: autumn 2013

Mission 1

Mission 2

GROOM Trieste 2013

Glider surface and full depth θ and S winter 2009/10

Top 12 m saltier and slightly warmer than top 800 m

Top 12 m fresher and much warmer than top 800m

Stratified Mixed

GROOM Trieste 2013

Ellett Line (Rockall Trough) Summary

Particular monitoring results from a glider:

• First winter upper 1000 m θ and S since 2006

• Overturning took place from mid-November to mid-January

• Salinity gradient reversed at the start of the overturning

• (Mesoscale motions follow next ...)

Long term implications:

• Better long term analysis and understanding of annual (and

seasonal) variability

• Opportunities for international collaboration (see later ...)

GROOM Trieste 2013

EXCITING STUFF

from the Ellett Line

GROOM Trieste 2013

Observations of θ, S, σt and velocity binned into 0.25° longitude cells

Nov / Dec 2009

GROOM Trieste 2013

Glider drift (to 1000 m) and equivalent altimeter geostrophic currents

GROOM Trieste 2013

Rockall

Rockall

Shelf

Shelf

Paper being prepared in collaborationwith Dima Alyenik (SAMS)

AVISO surface height anomaly Nov / Dec 2009

Slope current reversal?

GROOM Trieste 2013

Interim Research Results

• Rockall Trough has slow moving meso-scale eddies

• Typical eddy currents in upper 1000 m up to 25 cm/s

• Reversals of the northward flow in the eastern Trough

• These currents are driven by eddies deep waters of the Trough

(LSW and AABW)

• *Glider data show that deep water eddies can be tracked using

synthesised altimeter data*

Further work:

• Are WTOW eddies (from north) also in the mix?

• How well do altimeter and glider drift currents compare?

• Complete paper

GROOM Trieste 2013

OTHER NAGB ACTIVITIES

Nature, 9 May, 2013

SAMS Glider section

OSNAP (US / Canada / Holland / Germany / UK): $44m

NABG

OSNAP

GROOM Trieste 2013

Other work in the NE Atlantic

UK FASTNEt shelf edge study:a) Malin Shelf edge exchangeb) Faroe-Shetland Channel (with

MSS, Aberdeen)c) NACLIM partner collaboration

with Ellett Line

a)

b)

c)

GROOM Trieste 2013

Planned development of The North Atlantic Glider Base at SAMS

in association with NERC’s Marine Autonomous and Robotic Systems facility

(MARS), headed by NOC (Southampton and Liverpool)

A dedicated test facility for visitors:

• A covered glider building with Iridium / GPS repeaters, ballasting tank, WiFi etc

+ access to sheltered deep water

In house operational and research activities:

• Operating 5 – 6 gliders

• 1.5 PIs, 2 postdocs + 1-2 PhDs

• 1.5 technicians and 6 trained pilots

• Fully structured web interface (SAMS’ web interface to be extended and

incorporated by MARS)

• Data feeds on to BODC, GTS etc

• Publication of research papers

Shortly Coming to SAMS

GROOM Trieste 2013

Conclusions

• The Ellett Line glider programme is starting to show real

scientific benefit

• A much better understanding of mesoscale activity in the

Rockall Trough is emerging

• SAMS is extending its glider activity into other collaborative

programmes