Advertisement

Ocean Dynamics

, Volume 60, Issue 1, pp 93–122 | Cite as

On the response of a turbulent coastal buoyant current to wind events: the case of the Western Adriatic Current

  • Marcello G. MagaldiEmail author
  • Tamay M. Özgökmen
  • Annalisa Griffa
  • Michel Rixen
Article

Abstract

This numerical study focuses on the response of the Western Adriatic Current to wind forcing. The turbulent buoyant surface current is induced by the Po river outflow in the Adriatic Sea. Idealized and realistic wind conditions are considered by retaining the complex geomorphology of the middle Adriatic basin. In the absence of wind, the Adriatic Promontories force the current to separate from the coast and induce instabilities. Persistent 7-m s − 1 downwelling favorable northwesterly winds thicken and narrow the current. Instabilities whose size is ~10 km develop but ultimately vanish, since there is not enough across-shore space to grow. On the contrary, 7-m s − 1 upwelling favorable southeasterly winds thin and widen the current, and instabilities can grow to form mesoscale (~35 km) features. When realistic winds are considered, the same trends are observed, but the state of the sea set up by previous wind events also plays a crucial role. The turbulent regimes set up by different winds affect mixing and the WAC meridional transport. With downwelling winds, the transport is generally southward and mixing happens mostly between the fresher (S ≤ 38) salinity classes. With upwelling winds, the transport decreases and changes sign, and mixing mainly involves saltier (S > 38) waters. In all cases, mixing is enhanced when a finer 0.5-km horizontal resolution is employed.

Keywords

Mesoscale variability Adriatic Sea Western Adriatic Current Instabilities Gargano Promontory Cape Transport Mixing 

Notes

Acknowledgements

The research is supported by the National Science Foundation grant OCE0620661 (MGM, TMO), Office of Naval Research grants N00014-05-1-0094/95 (TMO, AG). A Rosenstiel School of Marine and Atmospheric Science Teaching Assistantship supported MGM. Insightful discussions on the numerical setup with Mehmet Ilıcak and on the wind data with Angelique Haza are also acknowledged. The Croatian Meteorological and Hydrological Service and Paul Martin are thanked for providing the wind data. All the simulations of this study were run thanks to the support of the High Performance Computing core at the Center for Computational Science of the University of Miami. The DART experiments were part of a Research Program lead jointly by the NATO Undersea Research Center and the Naval Research Laboratory at Stennis Space Center, in collaboration with 33 partner institutions whose contribution is gratefully acknowledged. The authors also thank Konstantin Korotenko and one anonymous reviewer for their comments and for improving the manuscript.

References

  1. Barale V, Rizzoli PM, Hendershott, MC (1984) Remotely sensing the surface dynamics of the Adriatic Sea. Deep Sea Res 31(12):1433–1459CrossRefGoogle Scholar
  2. Batchelor G (1967) An introduction to fluid dynamics. Cambridge University Press, Cambridge, 615 ppGoogle Scholar
  3. Bignami F, Sciarra R, Carniel S, Santoleri R (2007) Variability of Adriatic Sea coastal turbid water from SeaWiFS imagery. J Geophys Res 112:C03S10. doi: 10.1029/2006JC003518 CrossRefGoogle Scholar
  4. Blanton JO, Oey LY, Amft J, Lee TN (1989) Advection of momentum and buoyancy in a coastal frontal zone. J Phys Oceanogr 19:98–115CrossRefGoogle Scholar
  5. Blumberg AF, Mellor GL (1987) Three-dimensional coastal ocean models. American Geophysical Union, ch. A description of a three-dimensional coastal ocean circulation model, 208 ppGoogle Scholar
  6. Book JW, Signell RP, Perkins H (2007) Measurements of storm and nonstorm circulation in the northern Adriatic: October 2002 through April 2003. J Geophys Res 112:C11S92. doi: 10.1029/2006JC003556 CrossRefGoogle Scholar
  7. Burrage DM, Book JW, Martin PJ (2009) Eddies and filaments of the Western Adriatic Current near Cape Gargano: analysis and prediction. J Mar Syst. doi: 10.1016/j.jmarsys.2009.01.024 Google Scholar
  8. Canuto VM, Howard A, Cheng Y, Dubovikov MS (2001) Ocean turbulence, part I: one-point closure model—momentum and heat vertical diffusivities. J Phys Oceanogr 31:1413–1426CrossRefGoogle Scholar
  9. Capet X, McWilliams JC, Molemaker MJ, Shchepetkin AF (2008a) Mesoscale to submesoscale transition in the California Current system. Part I: flow structure, eddy flux, and observational tests. J Phys Oceanogr 38:29–43CrossRefGoogle Scholar
  10. Capet X, McWilliams JC, Molemaker MJ, Shchepetkin AF (2008b) Mesoscale to submesoscale transition in the California Current system. Part II: frontal processes. J Phys Oceanogr 38:44–64CrossRefGoogle Scholar
  11. Chanut J, Barnier B, Large W, Debreu L, Penduff T, Molines JM, Mathiot P (2008) Mesoscale eddies in the Labrador Sea and their contribution to convection and restratification. J Phys Oceanogr 38:1617–1643. doi: 10.1175/2008JPO3485.1 CrossRefGoogle Scholar
  12. Chao S-Y (1987) Wind-driven motion near inner shelf fronts. J Geophys Res 92:3849–3860CrossRefGoogle Scholar
  13. Chao S-Y (1988) Wind-driven motion of estuarine plumes. J Phys Oceanogr 18:1144–1166CrossRefGoogle Scholar
  14. Chapman DC, Lentz SJ (1994) Trapping of a coastal density front by the bottom boundary layer. J Phys Oceanogr 18:1464–1479CrossRefGoogle Scholar
  15. Chiggiato J, Oddo P (2008) Operational ocean models in the Adriatic Sea: a skill assessment. Ocean Sci 4:61–71Google Scholar
  16. Cushman-Roisin B, Gačić M, Poulain PM, Artegiani A (2001) Physical oceanography of the Adriatic Sea: past, present and future. Kluwer, Boston, 320 ppGoogle Scholar
  17. Cushman-Roisin B, Korotenko KA (2007) Mesoscale-resolving simulation of summer and winter bora events in the Adriatic Sea. J Geophys Res 112:C11S91. doi: 10.1029/2006JC003516 Google Scholar
  18. Cushman-Roisin B, Korotenko KA, Galos CE, Dietrich DE (2007) Simulation and characterization of the Adriatic Sea mesoscale variability. J Geophys Res 112:C03S14. doi: 10.1029/2006JC003515 Google Scholar
  19. Dong C, McWilliams JC (2007) A numerical study of island wakes in the Southern California Bight. Cont Shelf Res 27:1233–1248CrossRefGoogle Scholar
  20. Dong C, McWilliams JC, Shchepetkin AF (2007) Island wakes in deep water. J Phys Oceanogr 37:962–981. doi: 10.1175/JPO3047.1 CrossRefGoogle Scholar
  21. Flather R (1976) A tidal model of the northwest European continental shelf. Mem Soc R Sci Liege 6(10):141–164Google Scholar
  22. Fong DA, Geyer WR (2001) Response of a river plume during an upwelling wind event. J Geophys Res 106(C1):1067–1084CrossRefGoogle Scholar
  23. Fong DA, Geyer WR, Signell RP (1997) The wind-forced response of a buoyant coastal current: observation of the Gulf of Maine plume. J Mar Syst 12:69–81CrossRefGoogle Scholar
  24. Harrison DE, Robinson AR (1978) Energy analysis of open regions of turbulent flows: mean eddy energetics of a numerical ocean circulation experiment. Dyn Atmos Oceans 2:185–211CrossRefGoogle Scholar
  25. Jackett DR, McDougall TJ (1995) Minimal adjustment of hydrostatic profiles to achieve static stability. J Atmos Oceanic Technol 12(2):381–389CrossRefGoogle Scholar
  26. Korotenko KA (2007) Modeling the mesoscale variability in the Adriatic Sea. Oceanology 47(3):313–324CrossRefGoogle Scholar
  27. Kourafalou VH, Oey LY, Wang JD, Lee TN (1996) The fate of river discharge on the continental shelf 1. Modeling the river plume and the inner shelf coastal current. J Geophys Res 101:3415–3434CrossRefGoogle Scholar
  28. Lentz SJ (2001) The influence of stratification on the wind-driven cross-shelf circulation over the North Carolina shelf. J Phys Oceanogr 31:2749–2760CrossRefGoogle Scholar
  29. Lentz SJ, Helfrich KR (2002) Buoyant gravity currents along a sloping bottom in a rotating fluid. J Fluid Mech 464:251–278CrossRefGoogle Scholar
  30. Lentz SJ, Largier J (2006) The influence of wind forcing on the Chesapeake Bay buoyant coastal current. J Phys Oceanogr 36:1305–1316CrossRefGoogle Scholar
  31. Lutjeharms JRE, Penven P, Roy C (2003) Modelling the shear edge eddies of the southern Agulhas Current. Cont Shelf Res 23:1099–1115CrossRefGoogle Scholar
  32. Magaldi MG, Özgökmen TM, Griffa A, Chassignet EP, Iskandarani M, Peters H (2008) Turbulent flow regimes behind a coastal cape in a stratified and rotating environment. Ocean Model 25:65–82. doi: 10.1016/j.ocemod.2008.06.006 CrossRefGoogle Scholar
  33. Martin PJ, Book JW, Burrage DM, Rowley CD, Tudor M (2009) Comparison of model-simulated and observed currents in the central Adriatic during DART. J Geophys Res 114:C01S05. doi: 10.1029/2008JC004842 Google Scholar
  34. Martin PJ, Book JW, Doyle JD (2007) Simulation of the northern Adriatic circulation during winter 2003. J Geophys Res 112:C03S12. doi: 10.1029/2006JC003511 Google Scholar
  35. Münchow A, Garvine RW (1993) Buoyancy and wind forcing of a coastal current. J Mar Res 51:293–322CrossRefGoogle Scholar
  36. Oddo P, Pinardi N, Zavatarelli M (2006) A numerical study of the interannual variability of the Adriatic Sea (2000–2002). Sci Total Environ 353:39–56Google Scholar
  37. O’Reilly JE, Maritorena S, Mitchell BG, Siegel DA, Carder KL, Garver SA, Kahru M, McClain C (1998) Ocean color chlorophyll algorithm for SeaWiFS. J Geophys Res 103:24937–24953CrossRefGoogle Scholar
  38. Pasarić Z, Belušić D, Chiggiato J (2009) Orographic effects on meteorological fields over the Adriatic from different models. J Mar Syst. doi: 10.1016/j.jmarsys.2009.01.019 Google Scholar
  39. Paschini E, Artegiani A, Pinardi N (1993) The mesoscale eddy field of the Middle Adriatic Sea during fall 1988. Deep Sea Res 40(7):1365–1377CrossRefGoogle Scholar
  40. Pedlosky J (1987) Geophysical fluid dynamics, 2nd edn. Springer, New York, 710 ppGoogle Scholar
  41. Poulain, P-M (2001) Adriatic Sea surface circulation as derived from drifter data between 1990 and 1999. J Mar Syst 29:3–32CrossRefGoogle Scholar
  42. Poulain P-M, Mauri E, Ursella L (2004) Unusual upwelling event and current reversal off the Italian Adriatic coast in summer 2003. Geophys Res Lett 31:L05303. doi: 10.1029/2003GL019121 CrossRefGoogle Scholar
  43. Rixen M, Book J, Carta A, Grandi V, Gualdesi L, Stoner R, Ranelli P, Cavanna A, Zanasca P, Baldasserini G, Trangeled A, Lewis C, Trees C, Grasso R, Giannechini S, Fabiani A, Merani D, Berni A, Leonard M, Martin P, Rowley C, Hulbert M, Quaid A, Goode W, Preller R, Pinardi N, Oddo P, Guarnieri A, Chiggiato J, Carniel S, Russo A, Tudor M, Lenartz F, Vandenbulcke L (2009a) Improved ocean prediction skill and reduced uncertainty in the coastal region from multi-model super-ensembles. J Mar Syst. doi: 10.1016/j.jmarsys.2009.01.014 Google Scholar
  44. Rixen M, Book J, Orlic M (2009b) Coastal processes: challenges for monitoring and prediction. Preface. J Mar Syst. doi: 10.1016/j.jmarsys.2009.01.006 Google Scholar
  45. Schlichting H, Gersten K (2003) Boundary layer theory. Spinger, New York, 801 ppGoogle Scholar
  46. Shchepetkin AF, McWilliams JC (1998) Quasi-monotone advection schemes based on explicit locally adaptive dissipation. Mon Weather Rev 126(6):1541–1580CrossRefGoogle Scholar
  47. Shchepetkin AF, McWilliams JC (2005) The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model. Ocean Model 9(4):347–404CrossRefGoogle Scholar
  48. Silva M, Araujo M, Servain J, Penven P, Lentini CAD (2009) High-resolution regional ocean dynamics simulation in the southwestern tropical Atlantic. Ocean Model 30:256–269CrossRefGoogle Scholar
  49. Smolarkiewicz PK (1984) A fully multidimensional positive definite advection transport algorithm with small implicit diffusion. J Comput Phys 54:325–362CrossRefGoogle Scholar
  50. Sur Hİ, Özsoy E, Ünlûata Ü (1994) Boundary current instabilities, upwelling, shelf mixing and eutrophication in the Black Sea. Prog Oceanogr 33:249–302CrossRefGoogle Scholar
  51. Thomas LN, Ferrari R (2008) Friction, frontogenesis, frontal instabilities and the stratification of the surface mixed layer. J Phys Oceanogr 38:2501–2518CrossRefGoogle Scholar
  52. Thomas LN, Lee CM (2005) Intensification of ocean fronts by down-front winds. J Phys Oceanogr 35:1086–1102CrossRefGoogle Scholar
  53. Umlauf L, Burchard H (2003) A generic length-scale equation for geophysical turbulence models. J Marine Res 61:235–265CrossRefGoogle Scholar
  54. Veneziani M, Griffa A, Poulain P-M (2007) Historical drifter data and statistical prediction of particle motion: a case study in the central Adriatic Sea. J Atmos Ocean Technol 24:235–254. doi: 10.1175/JTECH1969.1 CrossRefGoogle Scholar
  55. Vetrano A, Gačić M, Kovačević V (1999) Water fluxes through the Strait of Otranto. Ecosystem Research Report 32, European CommissionGoogle Scholar
  56. Whitney MM, Garvine RW (2005) Wind influence on a coastal buoyant outflow. J Geophys Res 110:C03014. doi: 10.1029/2003JC002261 CrossRefGoogle Scholar
  57. Xing J, Davies AM (1999) The effects of wind direction and mixing upon the spreading of a buoyant plume in a non-tidal regime. Cont Shelf Res 19:1437–1483CrossRefGoogle Scholar
  58. Yankovsky AE, Chapman DC (1997) A simple theory for the fate of buoyant coastal discharges. J Phys Oceanogr 27:1386–1401CrossRefGoogle Scholar
  59. Zavatarelli M, Pinardi N (2003) The Adriatic Sea modelling system: a nested approach. Ann Geophys 21:345–364CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Marcello G. Magaldi
    • 1
    • 2
    Email author
  • Tamay M. Özgökmen
    • 2
  • Annalisa Griffa
    • 2
    • 3
  • Michel Rixen
    • 4
  1. 1.Department of Earth and Planetary SciencesThe Johns Hopkins UniversityBaltimoreUSA
  2. 2.Rosenstiel School of Marine and Atmospheric Science/MPOUniversity of MiamiMiamiUSA
  3. 3.Istituto di Scienze MarineConsiglio Nazionale, delle RicerchePozzuolo di Lerici (SP)Italy
  4. 4.NURCNATO Undersea Research CentreLa Spezia (SP)Italy

Personalised recommendations