Prévision opérationnelle de trajectoires de gliders en mission

Transcription

1 Prévision opérationnelle de trajectoires de gliders en mission P. Testor et al. CNRS/LOCEAN, Paris, France Colloque LEFE, 30 mars 2017, Clermont-Ferrand

2 Gliders: steered profiling floats Data centers users - Maneuverable: U ~ 25km/day - High resolution a dive to m in ~0.5-5h (= 1 or 2 vertical profiles spaced by ~0.5-5km) - Endurance up to 12 months (~3-4 months) - Physical, biogeochemical and biological sensors ECV/EOV: T, S, O2, Fluo Chl-a, + mean currents over the dives, Optical Backscatter, Fluo CDOM, PAR, Nitrates, ADCP, Microsctructure, Echosonders, Hydrophones, - Versatile and reusable

3 OceanGliders: a new associated program of the GOOS Like Argo, OceanSites,... Canada Started officially in September 2016 and endorsed by WMO/IOC JCOMM in October 2017 to support long term (sustained) glider observations, with a focus on scientific and societal stake

4 OceanGliders: a global coverage The glider data cover important gaps in the observation of the ocean, mainly in boundary areas and regional seas. There are today ~30 gliders at sea at any given time. Rationale efficient near boundaries, as they can rely only on small boats connect the coast and open ocean missions can be sustained indefinitely in key areas sampling is a good match to the spatial/temporal resolution required by important processes/regions: Boundary Currents, Storms, Water Transformation, Polar regions, BGC,...

5 OceanGliders: towards regional/coastal obs. system of systems 100 ~800 A publications from the global glider community ~ 100 pub./year ~French contribution: 70 pub since 2009 Regional scale Global scale OceanGliders (a global network of regional networks that monitor oceanic variability across international borders to the world s benefit): Provides coordination, expertise and linkage for a global observing program Supports regional efforts respectful of the coastal countries. Encourages sustained, year-round operation Helps to publish data in near-real time on the GTS and in CF compliant formats to a central data assembly center Provides improved and sustained quality control of glider data The GOOS needs to - address physical, biogeochemical and biological variability - extend the global system to regional seas and coastal ocean in order to further develop societal applications. OceanObs'09 OceanObs'19

6 Glider capacities Mediterranean SCV Cape Verde SCV Nitrates Basin scale (transatlantic) Mesoscale Submesoscale (SCVs, filaments, vertical vel.) Upwelling-Peru Physical, biogeochemical and biological (acoustics) measurements Coastal and under ice capacities Deep convection - plumes Gulf of Biscay - Turbidity Svalbard ice edge

7 Long term observations : example of MOOSE gliders French contribution to OceanGliders (boundary currents, Water mass transformation) Repeat-sections - ~10 days / ~300km - profiles m for T, S, O2 (and bio) - high resolution/coverage (space/time) 2 gliders in operation since 2009 (Ligurian Sea and Gulf of Lions) ~ at any time Nb of temperature profiles per year MOOSE 10,000 profiling floats gliders Ships XBTs Coverage enables new variability indices Ex: contrast between the coastal area and the open sea for the LIW

8 Gliders and process studies (e.g. DEWEX) MLD Objective analyses at seasonal scale AW - Sal (0-100m) MISTRALS HyMeX/MERMeX (INSU/ ANR + EU projects) Study of deep convection process and impact on marine ecosystem Multiscale and Multi-platform: Gliders, profiling floats, R/V cruises Over a seasonal cycle LIW Pot. Temp. ( m) Chl (0-bottom) Observing and modelling

9 Gliders and process studies (e.g. DEWEX) MLD Pot. Density ( m) Objective analyses at 10 days scale MLD, density over layers 3D view every 10 days of the water properties (OGCM-like but only in situ observations) Estimates of volumes of density classes over time First robust estimates of deep water formation rates Unprecedented benchmark for modelling

10 Gliders and process studies (e.g. DEWEX) MLD Pot. Density ( m) Objective analyses at 10 days scale MLD, density over layers 3D view every 10 days of the water properties (OGCM-like but only in situ observations) Estimates of volumes of density classes over time First robust estimates of deep water formation rates Unprecedented benchmark for modelling

11 Gliders and process studies (e.g. DEWEX) The optimal combination of different platforms allowed a coverage of profile observations never reached before new quantitative aspects Key role of gliders linking - Eulerian and Lagrangian other observations - the coastal/slope and open sea environment Detailed analysis of the processes: central role of SCVs, Symmetric Instability, and interactions between plumes/scvs and the bottom nepheloid layer New paradigm on the deep convection phenomenon and its impact on ocean ventilation and marine ecosystem (see Special issue in JGR: DEWEX Dense Water Formation Experiment (30 articles) for more details) Black: density contours Blue shade: ventilated waters

12 Towards highly augmented in situ sampling capacities Number of gliders AND smart piloting N Cyprus Demonstrations of coordinated fleet experiments and adaptive sampling Master-Slaves formation can be ensured thanks to the minimization of Lyapunov function with a parameter R (distance between gliders to keep) enable synoptic estimates of horizontal gradients at scale R Race and Routing examples using Lyapunov exponents from altimetry (indicating barriers/ highways in the ocean) Need to generate automated commands but asynchronous communications every 2-4h need of a glider simulator to predict trajectories (could be simple but better realistic)

13 LEFE/GMMC SIGLID project Based on the development of the realistic glider simulator SIGLID same commands as real gliders for piloting, quasi-static flight model using predicted environment variables (Temp. Density, Currents) from OGCM outputs (MERCATOR, CMEMS,...), extraction of OGCM variables along simulated trajectories output as real gliders in standard EGO format Objectives: Design of glider experiments (single or fleets of) for scientific purposes Navigational aid for gliders in mission (real time predictions of trajectories, routing,adaptive sampling, fleet coordination) Validation/intercomparison tool for operational oceanographic forecast services develop the utilization of operational products within the glider community (391 users registered on EGO) develop the use of glider data in operational oceanography community

14 LEFE/GMMC SIGLID project Based on the development of the realistic glider simulator SIGLID same commands as real gliders for piloting, quasi-static flight model using predicted environment variables (Temp. Density, Currents) from OGCM outputs (MERCATOR, CMEMS,...), extraction of OGCM variables along simulated trajectories output as real gliders in standard EGO format Objectives: Design of glider experiments (single or fleets of) for scientific purposes Navigational aid for gliders in mission (real time predictions of trajectories, routing,adaptive sampling, fleet coordination) Validation/intercomparison tool for operational oceanographic forecast services

15 LEFE/GMMC SIGLID project Based on the development of the realistic glider simulator SIGLID same commands as real gliders for piloting, quasi-static flight model using predicted environment variables (Temp. Density, Currents) from OGCM outputs (MERCATOR, CMEMS,...), extraction of OGCM variables along simulated trajectories output as real gliders in standard EGO format Objectives: Design of glider experiments (single or fleets of) for scientific purposes Navigational aid for gliders in mission (real time predictions of trajectories, routing,adaptive sampling, fleet coordination) Validation/intercomparison tool for operational oceanographic forecast services commands Data MERCATO R MFS HYCO M Data assimilation

16 LEFE/GMMC SIGLID project Based on the development of the realistic glider simulator SIGLID same commands as real gliders for piloting, quasi-static flight model using predicted environment variables (Temp. Density, Currents) from OGCM outputs (MERCATOR, CMEMS,...), extraction of OGCM variables along simulated trajectories output as real gliders in standard EGO format Objectives: Design of glider experiments (single or fleets of) for scientific purposes Navigational aid for gliders in mission (real time predictions of trajectories, routing,adaptive sampling, fleet coordination) Validation/intercomparison tool for operational oceanographic forecast services commands Data MERCATO R Ensemble predictions MFS HYCO M Data assimilation

17 LEFE/GMMC SIGLID project Based on the development of the realistic glider simulator SIGLID same commands as real gliders for piloting, quasi-static flight model using predicted environment variables (Temp. Density, Currents) from OGCM outputs (MERCATOR, CMEMS,...), extraction of OGCM variables along simulated trajectories output as real gliders in standard EGO format Objectives: Design of glider experiments (single or fleets of) for scientific purposes Navigational aid for gliders in mission (real time predictions of trajectories, routing,adaptive sampling, fleet coordination) Validation/intercomparison tool for operational oceanographic forecast services commands Ensemble predictions Data Data assimilation

18 LEFE/GMMC SIGLID project Based on the development of the realistic glider simulator SIGLID same commands as real gliders for piloting, quasi-static flight model using predicted environment variables (Temp. Density, Currents) from OGCM outputs (MERCATOR, CMEMS,...), extraction of OGCM variables along simulated trajectories output as real gliders in standard EGO format Objectives: Design of glider experiments (single or fleets of) for scientific purposes Navigational aid for gliders in mission (real time predictions of trajectories, routing,adaptive sampling, fleet coordination) Validation/intercomparison tool for operational oceanographic forecast services

19 Conclusions and prospects Gliders can - provide long term (physical, biogeochemical, biological) observations - increase our capacities for process studies (multi-scale/multi-platform) key component of present and future observing systems (~Galileo telescope) There is still a need to develop our glider deployment capacities for 'augmented' in situ sampling: on the long term (important areas not covered yet) for process studies (number of gliders, smart sampling) with respect to the science bay (new miniaturized sensors/measured variables) in order to improve our knowledge on ocean circulation and ecosystems.

20 Conclusions and prospects Gliders and numerical models: The data provided by gliders are a natural match for coastal/regional models of ocean circulation These coastal/regional models are necessary, as the currents and water properties in the coastal/regional ocean vary on the small scales set by topography/stratification/latitude Accurate forecasting depends on initialization on these small scales, which can be satisfied by a network of gliders From their earliest conception, underwater gliders were viewed as components of observing/modeling systems, and progress over the past decade has proven the efficacy of this approach. Still need to go further in that direction. Develop the dialogue with ocean data assimilators (data assimilation techniques: scales, variables) in order to develop more societal applications (regional/coastal) (see OceanGliders Storm Task Team - proven impact on hurricanes forecast intensity through coupled atmosphereocean glider data assimilation (NOAA)). Compare glider data with available operational ocean models to determine how the ensemble of operational ocean models currently represent the targeted phenomena ( SIGLID approach)

21 Merci!