Observations & Modelling!

Transcription

1 NEW CAPABILITIES OFFERED BY GLIDERS TO STUDY THE PHYSICAL-BIOLOGICAL COUPLING IN THE OCEAN Observations & Modelling! Courtesy Neptune, John Delaney, and Mark Stoermer P. Testor 1, A. Beszczynska-Moeller 2 1 LOCEAN, CNRS, Paris, France, 2 IOPAN, Sopot, Poland COST Conf. : The predictive Power of Marine Science in a Changing Climate, 7-8 April 2014, Institute of Oceanology, Sopot, Poland.

2 The Global Ocean Observation System (GOOS) in-situ system today : profiles T & S on [0-2000m] automatic measurements, transmitted in real-time «300km x 300km 10 days» Global numerical models (~6 km res.) MyOcean Courtesy of H. Freeland,

3 The Global Ocean Observation System (GOOS) Climateoriented Role of the ocean in climate: the ocean is a buffer of global change and transports heat from the tropics to the poles monitoring The OceanObs 09 symposium celebrated a decade of progress and made a major contribution providing guidelines for the next one. Extension: regional/coastal ocean biogeochemical (resources) gliders Sept. 2009, Venice, Italy Testor et al (2010): Gliders as a component of future observing systems

4 Gliders principle slocum exocetus A profiling float with wings Control of buoyancy and internal mass distribution no propeller! seaglider sterne Vertical velocity, pitch (and roll) Horizontal velocity (direction) spray seaexplorer

5 Gliders principle Data centers gliderman Users: Scientists, Operational Oceanography, etc. 1km U ~ 25 km/day (~ 0.5 knot) 2-4 km Physical and biogeochemical sensors (a profile in h ~ 0.5-5km) + depth-average currents (GPS + dead reckoning)

6 Gliders sensors A lot of different sensors (physical and biogeochemical) Conductivity, Temperature, Pressure Oxygen Fluorimeter Optical retrodiffusion (turbidity) Optical attenuation PAR sensor Spectrophotometer ( red tide ) Bathyphotometer (bioluminescence) Nitrate sensor Turbulence ADCP (currents) Hydrophone Acoustic modem But limited scientific bay (~2kg) and too many sensors reduce the endurance

7 Shelf monitoring (with on board acoustic altimeter) Ocean color temperature salinity oxygen shelf - Gulf of Biscaye River Gironde (very) fresh waters dispersal Strong tides CAROLS/GOGASMOS experiment 2009/05 8 sections of ~150km (5-6 days) ~1.5 month Tidal front chla fluorescence turbidity

8 Few first long range gliders (transoceanic) Glider Scarlett (2009) 221 days at sea 7410km Glider Silbo (2011) 330 days at sea 5315 km Rutgers Univ, USA Towards a WOCE 2.0 ships+gliders Complement the repeat global hydrography with gliders (tomorrow: down to 6000m - 97% of the ocean is less deep) World tour/race! (science fiction paper : Stommel, Oceanography, 1989) km 3 years (tomorrow: gliders will harvest energy from temperature differences)

9 A glider component in the GOOS Development of Operational Oceanography (EU Seas + adjacent oceans) Systematic and long-term measurements, rapid interpretation and dissemination Best practice for gliders! the formation of the global glider system; main gliderports the adoption of standards and a Argo like data system for gliders; the setup of a network of shared resources distributed and expertise; over the world to establish the adoption of a common and accessible portal for glider data. The challenge: bidirectional communications

10 A glider component in the GOOS (EU perspective) ~80 EU gliders + ~20 teams (and downstream infrastructures) A Research Infrastructure distributed in 6 ROOSes (+global: GOOS) A regional approach for the GOOS: ROOS (Regional Ocean Observing System) In connection with: Marine Board, EuroGOOS and similar EU projects: Jerico, EuroArgo, EuroSites, Eurofleets, MyOcean, Seadatanet, EMODNET, COST Action: Everyone s Gliding Observatories 16 countries (EU+Australia, South Africa, Mexico, Peru, Chile, USA) FP7 Design Study: Gliders for Research, Ocean Observation and Management, 19 partners (9 countries)

11 EGO and international coordination Harmonization (standards/formats) Monitoring the glider network activity (based on the operators good will but works) and data dissemination Maybe ~500,000 profiles since 2005 Process studies AND long-term observations All glider deployments since 2005 (+ deployments in the Artic/Antarctic, SE/SW Pacific, Polynesia, Indian ocean, ) IOOS/NGN USA 12,000 km altitude EU AU (EOOS?)/GROOM IMOS/ANFOG

12 Oceanic Processes global scale physical and biogeochemical variability Regional scale seasonal mesoscale submesoscale Extension of the global system to regional seas and coastal ocean Oceanographic cruises (ponctual) Regional and coastal models -«Green», BG objectives -«end-users» (MSFD, )

13 Regional and scientific context still open questions concerning the physical-biological coupling Different phenological regimes («temperate» and «tropical») in the same basin Deep Water Formation (ventilation) and subsequent INTENSE bloom Mistral+ Tramontane Preconditioning Violent vertical mixing Ecoregions from a cluster analysis Restratification/ spreading D Ortenzio & Ribera d Alcala, 2010 Marschall & Schot, 1999 MERMEX White Paper PIO, 2010 «.most of the questions that are still unresolved ( ) deal with the temporal variability of the key processes that govern the ( ) different physical, chemical and biological compartments. Observational limits are the principal causes of this uncertainty» Multi-platform experiment: continuous description over the water column at the basin/meso/submeso scales over a year

14 DEWEX: gliders, profiling floats, cruises, moorings Summer-Autumn Winter Spring 01/07/2012 -> 07/10/ Glider deployments ~ 13,000 profiles (0-1000m) 6 CTD cruises ~ 400 profiles (0-bottom) 27 Argo ~ 1,500 profiles (0-1000m or m) 10 Marisondes and surface drifters

15 DEWEX: gliders, profiling floats, cruises, moorings Projects: FP7 GROOM FP7 PERSEUS FP7 JERICO FP7 E-Aims FP7 OSS national funds HyMeX/MerMeX SOERE MOOSE ANR ASICS-MED EQUIPEX NAOS GMMC MESOLAB SOCIB REP12

16 Multidisplinary data at basin and meso/submeso scales Single platform, vertical section Pot. Fluo Turbidity Oxygen Salinity Dens. Temp Chla north south Northern Current Mixed patch North Balearic Front Small scale variability physical-biogeochemical coupling 193 km/h! Presence at sea even during strong weather conditions

17 Multidisplinary data at basin/meso/submeso scale 01 Feb to 15 Mar 2013

18 Evolution of the Eddy Kinetic Energy (0-1000m) Only average currents over 1000m dives EKE = (currents their running mean at ~50km)^2 U ~ 30cm/s First in-situ characterization of the EKE evolution at the basin scale over a year: U ~ 15cm/s U ~ 5cm/s violent and deep mixing Backgroung level of eddy activity Violent mixing and then conversion of potential energy into kinetic energy 2 months of strong eddy activity preconditioning mixing spreading Slow decay of (~2 months)

19 Analysis of Pot. Temp. [ m] & Chla [0-300m] Covariance functions for pot. Temperature averaged over m (deep convection) & chlorophyll 0-300m integrated contents (bloom) from autonomous platforms (spatiotemporal coverage) [0-300] Chla o C mg m -2 Oligotrophic Deep Bloom convection period period Spring period - Fall - Winter Bloom south-west starts around of Deep the Importance convection mixed of patch coastal area inputs

20 Glider observations in the Artic Fram Strait Observatory (FSO) in the entrance to the Arctic Ocean: repeated hydrography, moored array and gliders Main aim: monitoring volume, heat and freshwater exchanges between the North Atlantic and the Arctic Ocean repeated summer hydrography with CTD sections since 1999 (IO PAN) 16 deep moorings between the Spitsbergen and Greenland shelves since 1997 (AWI and NPI) 4-6 acoustic tomographic moorings operated (NERSC) gliders profiles ( m), mostly in open water with short under ice sections (AWI) in some years RAFOS sound sources for acoustic positioning and navigation (AWI)

21 Repeated glider section in Fram Strait in 2009 Temperature Depth-averaged currents 2-10 August summer August August Challenges in the West Spitsbergen Current: strong boundary current (up to 80 cm/s) significant deviations from planned trajectory Advantages of gliders sections: repeated high resolution CTD sections spring-autumn (aim year-round operations) less expensive than research vessels for repeated measurements in remote areas (but no water sample, no full depth, )

22 Acoustic RAFOS navigation of gliders under the sea ice Preparation and deployment of RAFOS sound sources Tests of acoustic navigation based on RAFOS signals since 2010 Sea ice concentration on July July 7, , RAFOS sound sources 260 Hz (central and western Fram Strait, depths > 2000m) Acoustic navigation based on RAFOS receiver on-board the glider and built-in software provided by APL-UW (Craig Lee) Acoustic ranges in open water of order O(100 km), in ice-covered areas of O(10 km) Signal from two sources enough to get position, (better accuracy from more sources)

23 Glider sections in open water and under ice in summer 2011 Histogram of error in acoustically derived positions Receptions of RAFOS signals from different sources summer 2011 under ice! winter 2011

24 Oceanic Processes global scale physical and biogeochemical variability Regional scale seasonal mesoscale submesoscale Extension of the global system to regional seas and coastal ocean Oceanographic cruises (ponctual) Regional and coastal models -«Green», BG objectives -«end-users» (MSFD, )

25 «EYE of the Levantine» project Sample the «warm core Cyprus eddy» + 6 gliders deployed of Limassol + 2 profiling floats + 4 surface drifters + shipborne measurements «TARA-Océans expédition» Gliders: physical et biogeochemical context for shipborne meausurements (biology, genomicas)

26 «EYE of the Levantine» project N Cyprus 3D view, salinity along the gliders (scouts) trajectories «Picture» of the Warm Core Cyprus Eddy context for biological measurements, float/drifter deployments

27 «EYE of the Levantine» project fleet piloting showcase Glider control timeline AI Control AI Control AI Control AI Control Periodic control loop (every 30 minutes) EGO Server (GFCP). Asynchronous and irregular Comm (~4 hours) Coordinated definition of waypoints using Lyapunov functions (Lekien et al 2008) 3 gliders 2 gliders Steering: Convergence:

28 «EYE of the Levantine» project fleet piloting showcase Satelitte altimetry (Sea Surface Dynamic Height) Piloting using Lagrangian Coherent Sctructures Race Route optimization Coordination: glider fleet in formation with a common mission Adaptation: maintain an optimat formation based on the performances and data collected, Cooperation: sampling of the target, Adaptive sampling: collect data where/when necessary Robustness: currents, asynchronous comm., delays/breaks in comm, Automation: automated or semi-automated (auto-pilot).

29 «EYE of the Levantine» project instantaneous Salinity (~5 days) skirt core skirt Mean radiale structure

30 Oceanic Processes global scale physical and biogeochemical variability Regional scale seasonal mesoscale submesoscale Extension of the global system to regional seas and coastal ocean Oceanographic cruises (ponctual) Regional and coastal models -«Green», BG objectives -«end-users» (MSFD, )

31 9 vertical sections off Peru 9 sections DENSITY SALINIT Y TEMPERATURE OXYGEN FLUORESCENCE 100km ~ 5 jours + currents averaged over the dives TURBIDITY

32 Vertical sections : ship vs glider Transect of R/V Olaya : 11 Oct - 13 Oct Glider section #2 : 08 Oct 13 Oct Open ocean : Warm at surface stratification ~ horizontal Transition zone : Strong horizontal gradients in the surface layer Upwelling : cold, salty and dense at surface

33 Interleaving, submesoscale circulations 3-5 stripes in salinity in the transition zone on each section Double diffusion? Kelvin-Helmoltz Instability? Inertial instability inertielle forced by the wind?

34 Thomas and Lee (2005) glider section # Nov satellite image - ocean color 14/16 Nov 2008 ~ 20 km Southern Hemisphere τ F H Analytical theory on the response of a front to a «down front» wind (inertial instability forced by the wind) L 0 L 0 = 4H L 0 distance between 2 downwelling (upwelling) zones q ml PV ; H mixed layer depth; f Coriolis parameter f 2 q ml Can induce secondary (stationary) vertical circulations : subduction on the dense side of the front upwelling at the interface

35 Interleaving, submesoscale circulations 2D Ertel s Potential Vorticity 2D (PV) : q = f N 2 f + PV <0 in frontal zones because of strong horizontal shear v x v z b x q ml q ml ~ s 14 ml s L ~ ~ km Consistent with the «layering» observed in salinity and fluorescence! Scale of vertical currents : w = with N F B eff 2 F H B eff = ~ 60 m / day F atm + M the effective buoyancy flux e b x z= 0

36 Conclusions Gliders can be operated in strong conditions (weather, currents, ice) and maintained in region of interests The Economist, 2012/06/09 make high res. measurement over long periods of time / distances be operated in coordinated fleets make us enter a new era in oceanography (are like scalpels or ~Galileo s telescope) Process studies and monitoring of physical and biogeochemical variability/coupling at large, meso, and submesoscale New societal applications (Blue Growth) scales resolved by gliders + sensors Environment MSFD (EEZ monitoring), Offshore operations (monitoring and emergency response - Deep Water Horizon), Ship routing, Security and naval warfare. (directly from data collected by gliders and through ocean analysis/forecast with regional/coastal models and data assimilation)