Cutting edge Science and Research from a Glider

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

West coast of Scotland Easy access to sheltered deep water and the North Atlantic launch point Local test sites Loch Linnhe (200 m) Ardmucknish Bay (30 m) 10 km 2013 GROOM Trieste Loch Etive (140 m) SAMS

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 Water WTOW – Wyville Thomson Ridge Overflow Water LSW – Labrador Sea Water AABW – Antarctic Bottom Water GROOM Trieste 2013

60 years of θ and S in the Rockall Trough (HADSST surface temps) OWS surface readings + winter top 4 m ● winter top 800 m Glider readings RRS full depth readings from: Sherwin, Read, Holliday and Johnson (2012) ICES Journal of Marine Science; doi: 10. 1093/icesjms/fsr 185 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 fresher and much warmer than top 800 m Top 12 m saltier and slightly warmer than top 800 m Mixed Stratified 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

AVISO surface height anomaly Nov / Dec 2009 Rockall Slope current reversal? Shelf Rockall Shelf Paper being prepared in collaboration with Dima Alyenik (SAMS) GROOM Trieste 2013

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

OTHER NAGB ACTIVITIES GROOM Trieste 2013

Nature, 9 May, 2013 SAMS Glider section NAB G OSNAP (US / Canada / Holland / Germany / UK): $44 m OSNAP

Other work in the NE Atlantic a) UK FASTNEt shelf edge study: a) Malin Shelf edge exchange b) Faroe-Shetland Channel (with MSS, Aberdeen) c) NACLIM partner collaboration with Ellett Line GROOM Trieste 2013 b) c)

Shortly Coming to SAMS 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, Wi. Fi etc + access to sheltered deep water In house operational and research activities: • Operating 5 – 6 gliders • 1. 5 PIs, 2 postdocs + 1 -2 Ph. Ds • 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 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 GROOM Trieste 2013