Recent advances in ocean circulation modelling and applications for oil spill preparedness

Transcription

1 Recent advances in ocean circulation modelling and applications for oil spill preparedness ZOE JACOBS E. Popova, J Hirschi, A. Yool, S. van Gennip, A. Coward, B. Anifowose, L.Harrington-Missin

2 Outline 1) High resolution ocean model at NOC 2) NOC + OSRL GOBLIN 3) Modelling oil spills in the Arctic

3 National Oceanography Centre Integrated ocean research and technology development from the coast to the deep ocean.

4 National Capability in High Resolution Global Ocean Modelling Global high resolution ocean model (NEMO) The model is run on a 43 million supercomputer, ARCHER (Academic Research Computing High End Resource) capable of more than one million billion calculations a second The model costs the Natural Environment Research Council (NERC) more than ~ 1 m/year in personnel costs alone to develop, run and analyse the model and its outputs.

5 Importance of resolution ~7km ~20km ~100km

6 Satellite-derived velocities 1 o 1/4 o 1/12 o AVISO Agulhas retroflection

7 Rubber ducks and ocean circulation

8 Oil spills and pollution modelling: preparedness vs response Response modelling Risk assessment modelling Operational (based on realtime forward prediction) Deals with a specific situation as it develops Considers short time scales relevant to the clean-up operation Emergency

9 Oil spills and pollution modelling: preparedness vs response Response modelling Operational (based on realtime forward prediction) Deals with a specific situation as it develops Considers short time scales relevant to the clean-up operation Emergency Risk assessment modelling Non-operational (based on modelling of the recent past) Considers full range of possible scenarios Aims at longer timescales and wider spatial scales Deals with the worst case scenario

10 Use of circulation models by the industry The model most commonly used: SINTEF oil spill model embedded into Norwegian MO Operational model (HYCOM) Why? Circulation at daily resolution for two years are readily available free of charge (1990 and 91) Concern: use of a single circulation model No single model will work universally well across all areas HYCOM does not perform well at high latitudes Only considering 2 years Can leading UK model be of use?

11 NOC-OSRL collaborative project For the probabilistic analysis of the oil spill impact OSRL needs to run OSCAR embedded into multiple time periods of the circulation fields (e.g. releases starting in different seasons and/or years). The process is computationally expensive Can we design a similar (and computationally much cheaper) experiments which will show details of the ocean circulation relevant to the potential transport of oil by ocean currents?

12 Methodology Assess seasonal & interannual variability of the ocean circulation in NEMO Lagrangian particle tracking software Ariane used to represent a hypothetical oil spill 400 oil particles released at multiple depths & times Seasonal experiment: beginning of every month for 1 year Interannual experiment: beginning of every year for 31 years

13 AVISO Surface Currents NEMO Decadal mean Annual mean Monthly mean

14 Interannual probabilistic footprints Gulf of Mexico 10m 500m 1000m Faroe-Shetland channel Brazilian shelf Angola shelf # particles per grid cell for 31 releases (IA experiment)

15 MHD Metric Modifed Hausdorff Distance (MHD) Shape-distance metric Measures similarity in shape d(a,b) d(a,b) Circulation footprint left by hypothetical oil spill compared to control shape Control shape: area of cumulative footprints with oil particle density closest to average area of individual footprints A, B

16 Brazil Shelves Seasonal Variability Angola Shelf Faroe-Shetland Channel Gulf of Mexico

17 Gulf of Mexico seasonal extremes Periodic Loop Current eddy shedding (Oey et al., 2005) Loop current location near site enabling entrainment into GS

18 Angola Shelf seasonal extremes Angola Current smaller footprint Southern Equatorial Current larger footprint

19 Brazilian shelves seasonal extremes Seasonal shifts in confluence zone (Goni & Wainer, 2001) Seasonal variation in speed & location of Brazil Current (e.g. Wainer et al., 2000)

20 Faroe-Shetland Channel seasonal extremes Barents Sea shelf circulation anomalies from low pressure systems (Lien et al., 2013) Strengthened Norwegian Current in winter (Jakobsen et al., 2003)

21 Brazil shelves Interannual Variability Gulf of Guinea Faroe-Shetland Channel Gulf of Mexico

22

23 Gulf of Mexico interannual extremes Encountered both (left) / neither (right) eddy activity or the Loop Current Seas & InterA variability similar episodic eddy shedding (Sturges & Leben, 2000)

24 Angola Shelf interannual extremes Decadal variability possibly from Benguela Niños Strong SEC highest MHD uncommon pathway

25 Brazilian Shelves interannual extremes Vitoria-Trinade ride south of site interaction with Brazil Current eddies (Soutelino et al., 2011) IA variability exists in speed of Brazil Current (Goni & Wainer, 2001) & location of confluence zone (Garzoli & Giulivi, 1994)

26 Faroe-Shetland Channel interannual extremes + NAO stronger W lies in SPG greater transport of NwAC & WSC (Eden & Willebrand, 2001) Slow Norwegian Current possibly enabled entrainment into North Sea Current

27 Summary from GOBLIN Ocean circulation plays a crucial role in the propagation of oil spills. Demonstrated that a highresolution global ocean circulation model can be used to assess the seasonal and interannual variability of potential oil spills. Complements the conventional oil spill preparedness modelling usually performed by environmental consultancies.

28 Outline 1)High resolution ocean model at NOC 2)NOC + OSRL GOBLIN 3)Modelling oil spills in the Arctic

29 Loss of Arctic sea-ice under RCP 8.5

30 Impact of Arctic ice retreat Arctic shipping routes

31 Oil spills in ice-covered Arctic: Basic facts Spilled oil can potentially be trapped in or under the ice and drift with the ice cover Weathering of oil in freezing temperatures and in the presence of ice occurs more slowly Oil spills encapsulated in ice during the freeze-up period will be returned to the surface during the spring thaw

32 Oil spills in the Arctic Investigating circulation pathways relevant to an oil spill in the Arctic. 100 particles launched from each site every 10 days from June October Large footprint = more uncertainty. Example from 2007 release for 2 years.

33

34

35

36

37

38

39

40

41

42 Shallow and follow Trans-Arctic route Reach Atlantic after 2 years Deepen

43 24 Hour EU Project Given a specific location for a hypothetical oil spill In 24 hours, needed 6 month projections of potential footprints Similar experiment design with releases taking place from Significant variability discovered.

44 Example of Variability of Circulation Pathways

45 Aug 2001 Normal Flow

46 Aug 2004 Reverse Flow

47 Collaborating with NOC NERC Knowledge Exchange Fellowships Part time Knowledge Exchange Fellowships are available in any area of policy, business or third sector with the aim of boosting the impact of any type of NERC funded science NERC Knowledge Exchange project Collaborative projects between industry and NERC scientists demonstrating impact of NERC funded science on business performance

48 Thank you.

49

50 Online NEMO output Information on past, present-day and future ocean and sea ice (1948-now-2099): 3-D currents, ocean temperature, salinity, turbulence, icebergs spread & sizes Sea ice thickness, ice types, concentration, floe sizes, ice compressive/shear pressure Available from June 2016