Dr Marc Lucas CLS Toulouse, France.

Transcription

1 Dr Marc Lucas CLS Toulouse, France. Oceanology International 15th March 2012 Slide 1

2 Ocean depiction In the past: Information mainly comes from in situ measurements (ADCP) Now: The role of satellite data and numerical models will become increasingly important for offshore applications Oceanology International 15th March 2012 Slide 2

3 Surface currents Today the knowledge of sea surface currents is not accurate enough for many operations at sea New methodology: To compute and forecast sea surface currents Hybrid currents That combines: In situ data Satellite observations Numerical atmospheric and ocean models Oceanology International 15th March 2012 Slide 3

4 In situ observations Oceanographic in situ data: ADCP Buoys (Argo, moored buoys ) Sensors on ships T/S profiles from CTD, XBT, Argo floats, moorings Surface currents from surface drifters Accurate data but limited to one point (no regional visibility) Oceanology International 15th March 2012 Slide 4

5 Need to improve the surface currents At higher frequencies In space (increased spatial resolution) In time (higher frequency) Accuracy Along coastlines In shallow waters Whilst keeping the accuracy of open ocean products derived from satellite observations Oceanology International 15th March 2012 Slide 5

6 Observations from space Types of satellite observations: Altimetry: ocean topography Sea Surface Heights Surface Currents Ocean Colour Sea Surface Temperature Oceanology International 15th March 2012 Slide 6

7 Observations from space Jason Advantages of satellite observations : 2D regional visibility Long-term monitoring (over 20 years) Real-time monitoring (a few hours) Envisat Aqua Oceanology International 15th March 2012 Slide 7

8 Altimetry With satellite observations of ocean topography and currents: Anticyclonic (bump) Cyclonic (hollow) Currents are turning around eddies Oceanology International 15th March 2012 Slide 8

9 Ocean colour To locate and monitor eddies To detect and monitor river plumes To track eddies To locate currents (coastal currents, Loop Current ) Ocean color : trace the movement of water masses from space Oceanology International 15th March 2012 Slide 9

10 Sea Surface Temperature To locate fronts To locate upwelling To separate water masses Sea surface temperature : locate water masses from space Oceanology International 15th March 2012 Slide 10

11 Numerical ocean models Provides ocean currents in 2D or 3D over time Not real observation but regional visibility and forecast possibility Oceanology International 15th March 2012 Slide 11

12 Tide models Global tide model (open boundaries) Regional models (refines meshes) High frequency hourly currents Oceanology International 15th March 2012 Slide 12

13 Atmospheric models Winds extracted from: European Centre Medium RangeWeather Forecasting products Regional weather models Used to compute wind driven currents Oceanology International 15th March 2012 Slide 13

14 Hybrid surface currents Main idea => to combine : Satellite observations In situ observations Numerical models outputs (atmospheric and ocean) To take advantage of all the main characteristics of each of these inputs Oceanology International 15th March 2012 Slide 14

15 Hybrid surface current Oceanology International 15th March 2012 Slide 15

16 Hybrid currents schematic Altimetric heights Observations Altimetric currents Wind stress Bathymetry Numerical ocean model SWW2D model Data Fitting Sea Surface Temperature Ocean Color Tidal potential SQG Model SQG Model Tide Model Hybrid surface current Oceanology International 15th March 2012 Slide 16

17 Main characteristics Hybrid currents: Spatial resolution: 1/30 (~4km) Time resolution: Hourly Forecast: 48h Oceanology International 15th March 2012 Slide 17

18 Offshore Angola results Comparison with drifters in the area: 4 S-8 S; 9 E-15 E DRIFTERS ANGOLA HYBRID MODEL Oceanology International 15th March 2012 Page 18

19 Data Fitting Important to anchor model field to in situ observation Oceanology International 15th March 2012 Slide 19

20 Data Fitting Oceanology International 15th March 2012 Slide 20

21 Conclusion New method developed to provide 2D vision Massively based on observations: Satellite (SST,SSH,OC) In situ (ADCP, buoys) Uses also input from models Results are promising but: Lack of observations is the main obstacle Very cheap numerically: allows the possibility of stochastic (ensemble) modeling. Oceanology International 15th March 2012 Slide 21

22 Please come and visit us on stand E450 Oceanology International 15th March 2012 Slide 22