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Assimilating along-track SLA data using the EnOI in an eddy resolving model of the Agulhas system

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Abstract

The greater Agulhas Current is one of the most energetic current systems in the global ocean. It plays a fundamental role in determining the mean state and variability of the regional marine environment, affecting its resources and ecosystem, the regional weather and the global climate on a broad range of temporal and spatial scales. In the absence of a coherent in-situ and satellite-based observing system in the region, modelling and data assimilation techniques play a crucial role in both furthering the quantitative understanding and providing better forecasts of this complicated western boundary current system. In this study, we use a regional implementation of the Hybrid Coordinate Ocean Model and assimilate along-track satellite sea level anomaly (SLA) data using the Ensemble Optimal Interpolation (EnOI) data assimilation scheme. This study lays the foundation towards the development of a regional prediction system for the greater Agulhas Current system. Comparisons to independent in-situ drifter observations show that data assimilation reduces the error compared to a free model run over a 2-year period. Mesoscale features are placed in more consistent agreement with the drifter trajectories and surface velocity errors are reduced. While the model-based forecasts of surface velocities are not as accurate as persistence forecasts derived from satellite altimeter observations, the error calculated from the drifter measurements for eddy kinetic energy is significantly lower in the assimilation system compared to the persistence forecast. While the assimilation of along-track SLA data introduces a small bias in sea surface temperatures, the representation of water mass properties and deep current velocities in the Agulhas system is improved.

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References

  • Antonov JI, Locarnini RA, Boyer TP, Mishonov AV, Garcia HE (2006) World Ocean Atlas 2005, Volume 1: Salinity., p. 182 pp. NOAA Atlas NESDIS 61. U.S. Government Printing Office, Washington

    Google Scholar 

  • Backeberg BC, Johannessen JA, Bertino L, Reason CJ (2008) The greater Agulhas Current system: an integrated study of its mesoscale variability. J Oper Oceanogr 1(1):29–44

    Google Scholar 

  • Backeberg BC, Bertino L, Johannessen JA (2009) Evaluating two numerical advection schemes in HYCOM for eddy-resolving modelling of the Agulhas Current. Ocean Sci 5:173–190

    Article  Google Scholar 

  • Backeberg BC, Johannessen JA, Rouault M, Veitch J (2010) Preliminary inter-model comparison of the Agulhas Current with direct range doppler velocity estimates from Envisats Advance Synthetic Aperture Radar In: Special Publication SP-686 on CD. Eurpean Space Agency, ESAs Publications Division (EPD)

  • Backeberg BC, Penven P, Rouault M (2012) Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. Nat Clim Chang 2:608–612

    Article  Google Scholar 

  • Backeberg BC, Reason CJ (2010) A connection between the South Equatorial Current north of Madagascar and Mozambique Channel Eddies. Geophys Res Lett 37:L04604. doi:10.1029/2009GL041950

    Article  Google Scholar 

  • Barnier B, Madec M, Pendruff T, Molines JM, Treguier AM, Sommer JL, Beckmann A, Biastoch A, Böning C, Dengg J, Derval C, Durand E, Gulev S, Remy E, Talandier C, Theetten S, Maltrud M, McClean J, DeCuevas B (2006) Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy permitting resolution. Ocean Dyn 56(5-6):543–567

    Article  Google Scholar 

  • Beal LM, De Ruijter WPM, Biastoch A, Zahn R (2011) On the role of the Agulhas system in ocean circulation and climate. Nat 472:429–436

    Article  Google Scholar 

  • Bentsen M, Evensen G, Drange H, Jenkins AD (1999) Coordinate transformation on a sphere using conformal mapping. Mon Weather Rev 127:2733–2740

    Article  Google Scholar 

  • Biastoch A, Böning CW, Lutjeharms JRE (2008) Agulhas leakage dynamics affects decadal variability in Atlantic overturning circulation. Nat 456:489492

    Article  Google Scholar 

  • Biastoch A, Böning CW, Schwarzkopf FU, Lutjeharms JRE (2009) Increase in Agulhas leakage due to poleward shift of Southern Hemisphere westerlies. Nat 462:495–498

    Article  Google Scholar 

  • Biastoch A, Lutjeharms JRE, Böning CW, Scheinert M (2008) Mesoscale perturbations control inter-ocean exchange south of Africa. Geophys Res Lett 35:L20, 602

    Article  Google Scholar 

  • Bleck R (2002) An oceanic general circulation model framed in hybrid isopycnic-Cartesian coordinates. Ocean Model 37:55–88

    Article  Google Scholar 

  • Browning GL, Kreiss HO (1982) Initialization of the shallow water equations with open boundaries by the bounded derivative method. Tellus 34:334–351

    Article  Google Scholar 

  • Browning GL, Kreiss HO (1986) Scaling and computation of smooth atmospheric motions. Tellus Ser A 38:295–313

    Article  Google Scholar 

  • Byrne DA, McClean JL (2008) Sea level anomaly signals in the Agulhas Current region. Geophys Res Lett 35. doi:10.1029/2008GL034087

  • Chelton DB, Deszoeke RA, Schlax MG, El Naggar K, Siwertz N (1998) Geographical variability of the first baroclinic Rossby radius of deformation. J Phys Oceanogr 28(3):433–460

    Article  Google Scholar 

  • Counillon F, Bertino L (2009) Ensemble Optimal Interpolation: Multivariate properties in the Gulf of Mexico. Tellus 61:296308

    Article  Google Scholar 

  • Counillon F, Bertino L (2009) High-resolution ensemble forecasting for the Gulf of Mexico eddies and fronts. Ocean Dyn 59:83–95

    Article  Google Scholar 

  • Crosby DS, Breaker LC, Gemmill WH (1993) A proposed definition for vector correlation in geophysics: Theory and application. J Atmos Ocean Technol 10:355–367

    Article  Google Scholar 

  • Dee DP, Uppala SM, Simmons AJ, Berrisford P, Poli P, Kobayashi S, Andrae U, Balmaseda MA, Balsamo G, Bauer P, Bechtold P, Beljaars ACM, van de Berg L, Bidlot J, Bormann N, Delsol C, Dragani R, Fuentes M, Geer AJ, Haimberger L, Healy SB, Hersbach H, Hólm EV, Isaksen L, Kållberg P, Köhler M, Matricardi M, McNally AP, Monge-Sanz BM, Morcrette JJ, Park BK, Peubey C, de Rosnay P, Tavolato C, Thpaut JN, Vitart F (2011) The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Q J R Meteorol Soc 137(656):553–597. doi:10.1002/qj.828

  • Dibarboure G, Pujol MI, Briol F, Traon PYL, Larnicol G, Picot N, Mertz F, Ablain M (2011) Jason-2 in DUACS: Updated system description, first tandem results and impact on processing and products. Mar Geodesie 34(3-4):214–241

    Article  Google Scholar 

  • Drange H, Simonsen K (1996) Formulation of air-sea fluxes in the ESOP2 version of MICOM. Technical Report No. 125. Nansen Environmental and Remote Sensing Center

  • Ducet N, Le Traon PYL, Reverdin G (2000) Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. J Geophys Res 105:19, 477–19, 498

    Article  Google Scholar 

  • Emery WJ, Meincke J (1986) Global water masses: Summary and review. Oceanol Acta 9(4)

  • Evensen G (2003) The Ensemble Kalman Filter: Theoretical formulation and practical implementation. Ocean Dyn 53:343–367

    Article  Google Scholar 

  • Evensen G, van Leeuwen P (1996) Assimilation of Geosat altimeter data for the Agulhas Current using the Ensemble Kalman Filter with a quasi-geostrophic model. Mon Weather Rev 24:85–96

    Article  Google Scholar 

  • Gaspari G, Cohn SE (1999) Construction of correlation functions in two and three dimensions. Q.J.R. Meteorol Soc 125:723–757

    Article  Google Scholar 

  • George MS, Bertino L, Johannessen OM, Samuelsen A (2010) Validation of a hybrid coordinate ocean model for the Indian Ocean. J Oper Oceanogr 3(2):25–38

    Google Scholar 

  • Kara A, Rochford, PA Hurlburt HE (2000) Efficient and accurate bulk parameterizations of air-sea fluxes for use in general circulation models. J Atmos Ocean Technol 17:1421–1438

    Article  Google Scholar 

  • Locarnini RA, Mishonov AV, Antonov JI, Boyer TP, Garcia HE (2006) World Ocean Atlas 2005, Volume 1: Temperature., p. 182 pp. NOAA Atlas NESDIS 61. U.S. Government Printing Office, Washington

    Google Scholar 

  • Lumpkin R, Pazos M (2007) Lagrangian Analysis and Prediction of Coastal and Ocean Dynamics (LAPCOD), chap. 2: Measuring surface currents with Surface Velocity Program drifters: the instrument, its data, and some recent results. Cambridge University Press

  • Lutjeharms JRE (2006) The Agulhas Current. Springer-Praxis Books

  • Lutjeharms JRE, Ansorge I (2001) The Agulhas Return Current. J Mar Sys 30:115–138

    Article  Google Scholar 

  • Lutjeharms JRE, Webb DJ (1995) Modelling the Agulhas current system with FRAM (fine resolution antarctic model). Deep Sea Res.Part I 42:523–551

    Google Scholar 

  • Meehl GA, Goddard L, Murphy J, Stouffer RJ, Boer G, Danabasoglu G, Dixon K, Giorgetta MA, Greene AM, Hawkins E, Hegerl G, Karoly D, Keenlyside N, Kimoto M, Kirtman B, Navarra A, Pulwarty R, Smith D, Stammer D, Stockdale T (2009) Decadal Prediction. Bull Amer Meteor Soc 90:14671485

  • Oke P, Allen J, Miller R, Egbert G, Kosro P (2002) Assimilation of surface velocity data into a primitive equation coastal ocean model. J Geophys Res 107:511. doi:10.1029/2000JC000

  • Oke P, Sakov P, Corney S (2007) Impacts of localisation in the EnKF and EnOI: Experiments with a small model. Ocean Dyn 57:32–45

    Article  Google Scholar 

  • Oke P, Schiller A, Griffin D, Brassington G (2005) Ensemble data assimilation for an eddy-resolving ocean model of the Australian Region. Q Jl R Met Soc 131:33013311

    Article  Google Scholar 

  • Oke PR, Brassington GB, Griffin DA, Schiller A (2008) The Bluelink ocean data assimilation system (BODAS). Ocean Model 21:46–70

    Article  Google Scholar 

  • Oki T, Sud YC (1998) Design of the global river channel network for Total Runoff Integrating Pathways (TRIP). Earth Interactions 2(2-001):1–37

    Article  Google Scholar 

  • Ollitrault M, Rannou J (2013) ANDRO: an Argo-based deep displacement dataset. J Atmos Ocean Technol 30(4):759–788

    Article  Google Scholar 

  • Peeters FJC, Acheson R, Brummer GA, de Ruijter WPM, Schneider RR, Ganssen GM, Ufkes E, Kroon D (2004) Vigorous exchange between the Indian and Atlantic oceans at the end of the past five glacial periods. Nat 430:661–665

    Article  Google Scholar 

  • Penven P, Chang N, Shillington F (2006) Modelling the Agulhas Current using SAfE (Southern Africa Experiment). In: Proc. EGU General Assembly. Vienna

  • Penven P, Herbette S, Rouault M (2010) Ocean Modelling in the Agulhas Current System. In: Proceedings of the Joint Nansen-Tutu Scientific Opening Symposium and OceanSAfrica Meeting. Nansen-Tutu Centre for Marine Environmental Research

  • Rio MH, Guinehut S, Larnicol G (2011) New CNES-CLS09 global mean dynamic topography computed from the combination of GRACE data, altimetry, and in situ measurements. J Geophys Res 116:C07018. doi:10.1029/2010JC006505

  • Rouault M, Penven P, Pohl B (2009) Warming in the Agulhas Current system since the 1980s. Geophys Res Lett L12:602

    Google Scholar 

  • Schiller R, Kourafalou V (2010) Modeling river plume dynamics with the Hybrid Coordinate Ocean Model. Ocean Model. doi:10.1016/j.ocemod.2009.12.005

  • van Sebille E, Biastoch A, van Leeuwen PJ, de Ruijter WPM (2009) A weaker Agulhas Current leads to more Agulhas leakage. Geophys Res Lett 36. doi:10.1029/2008GL036614

  • Srinivasan A, Chassignet E, Bertino L, Brankart J, Brasseur P, Chin T, Counillon F, Cummings J, Mariano A, Smedstad O, Thacker W (2011) A comparison of sequential assimilation schemes for ocean prediction with the HYbrid Coordinate Ocean Model (HYCOM): Twin experiments with static forecast error covariances. Ocean Model 37:85–111

    Article  Google Scholar 

  • Steele M, Morley R, Ermold W (2001) PHC: a global ocean hydrography with a high quality Arctic Ocean. J Clim 14:2079–2087

    Article  Google Scholar 

  • Thoppil PG, Richman JG, Hogan PJ (2011) Energetics of a global ocean circulation model compared to observations. Geophys Res Lett 38. doi:10.1029/2011GL048347

  • Wallcraft AJ, Metzger EJ, Carroll SN (2009) Software Design Description for the HYbrid Coordinate Ocean Model (HYCOM) Version 2.2. Technical Report NRL/MR/7320–09-9166. Naval Research Laboratory

  • Wunsch C, Stammer D (1998) Satellite altimetry, the marine geoid, and the oceanic circulation. Annu Rev Earth Planet Sci 26:219–253

    Article  Google Scholar 

  • Xie J, Counillon F, Zhu J, Bertino L (2011) An eddy resolving tidal-driven model of the South China Sea assimilating along-track SLA data using the EnOI. Ocean Sci 7:609–627

    Article  Google Scholar 

Download references

Acknowledgments

This work has been jointly supported by the Nansen-Tutu Centre for Marine Environmental Research, Cape Town, South Africa, the South African National Research Foundation through the Grant 87698, the Nansen Environmental and Remote Sensing Center, Bergen, Norway, and through the EU FP7 Marie Curie International Research Staff Exchange Scheme (IRSES) Fellowship SOCCLI “The role of Southern Ocean Carbon cycle under CLImate change”, which received funding from the European Commission’s Seventh Framework Programme under grant agreement number 317699. This work has also received a grant for computer time from the Norwegian Program for supercomputing (NOTUR project number nn2993k). The altimeter products used in this study was produced by Ssalto/Duacs and distributed by Aviso, with the support from CNES (http://www.aviso.oceanobs.com/duacs/), and the surface drifter data were made available through the Data Assembly Center of the NOAA AOML Physical Oceanography Division. The Argo data were collected and made freely available by the Coriolis project and programmes that contribute to it (http://www.coriolis.eu.org).

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Authors and Affiliations

  1. Nansen-Tutu Centre for Marine Environmental Research, Department of Oceanography, Marine Research Institute, University of Cape Town, Private Bag X3 Rondebosch, 7701, Cape Town, South Africa

    Björn C. Backeberg

  2. Nansen Environmental and Remote Sensing Center, Thormø hlensgate 47, 5006, Bergen, Norway

    François Counillon & Johnny A. Johannessen

  3. Collecte Localisation Satellites (CLS), 8-10 rue Hermès, Parc technologique du Canal, 31520, Ramonville Saint-Agne, France

    Marie–Isabelle Pujol

Authors
  1. Björn C. Backeberg
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  2. François Counillon
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  3. Johnny A. Johannessen
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  4. Marie–Isabelle Pujol
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Correspondence to Björn C. Backeberg.

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Responsible Editor: Leo Oey

This article is part of the Topical Collection on the 5th International Workshop on Modelling the Ocean (IWMO) in Bergen, Norway 17–20 June 2013

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Backeberg, B.C., Counillon, F., Johannessen, J.A. et al. Assimilating along-track SLA data using the EnOI in an eddy resolving model of the Agulhas system. Ocean Dynamics 64, 1121–1136 (2014). https://doi.org/10.1007/s10236-014-0717-6

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