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Boundary-Layer Meteorology

, Volume 123, Issue 2, pp 219–237 | Cite as

Effects of mesoscale sea-surface temperature fronts on the marine atmospheric boundary layer

  • Eric D. SkyllingstadEmail author
  • Dean Vickers
  • Larry Mahrt
  • Roger Samelson
Original Paper

Abstract

A numerical modelling study is presented focusing on the effects of mesoscale sea-surface temperature (SST) variability on surface fluxes and the marine atmospheric boundary-layer structure. A basic scenario is examined having two regions of SST anomaly with alternating warm/cold or cold/warm water regions. Conditions upstream from the anomaly region have SST values equal to the ambient atmosphere temperature, creating an upstream neutrally stratified boundary layer. Downstream from the anomaly region the SST is also set to the ambient atmosphere value. When the warm anomaly is upstream from the cold anomaly, the downstream boundary layer exhibits a more complex structure because of convective forcing and mixed layer deepening upstream from the cold anomaly. An internal boundary layer forms over the cold anomaly in this case, generating two distinct layers over the downstream region. When the cold anomaly is upstream from the warm anomaly, mixing over the warm anomaly quickly destroys the shallow cold layer, yielding a more uniform downstream boundary-layer vertical structure compared with the warm-to- cold case. Analysis of the momentum budget indicates that turbulent momentum flux divergence dominates the velocity field tendency, with pressure forcing accounting for only about 20% of the changes in momentum. Parameterization of surface fluxes and boundary-layer structure at these scales would be very difficult because of their dependence on subgrid-scale SST spatial order. Simulations of similar flow over smaller scale fronts (<5 km) suggest that small-scale SST variability might be parameterized in mesoscale models by relating the effective heat flux to the strength of the SST variance.

Keywords

Internal boundary layer Large-eddy simulation Marine boundary layer SST variability 

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References

  1. Attie JL, Durand P (2003) Conditional wavelet technique applied to aircraft data measured in the thermal internal boundary layer during sea-breeze events. Boundary-Layer Meteorol 106:359–382CrossRefGoogle Scholar
  2. Chelton DB, Esbersen SK, Schlax MG, Thum N, Freilich MH, Wentz FJ, Gentemann CL, McPhaden MJ, Schopf PS (2001) Observations of coupling between surface wind stress and sea surface temperature in the eastern tropical Pacific. J Climate 14:1479–1498CrossRefGoogle Scholar
  3. Chelton DB, Schlax MG, Freilich MH, Milliff RF (2004) Satellite measurements reveal persistent small-scale features in ocean winds. Science 303:978–983CrossRefGoogle Scholar
  4. Deardorff JW (1980) Stratocumulus-capped mixed layers derived from a three-dimensional model. Boundary-Layer Meteorol 18:495–527CrossRefGoogle Scholar
  5. Ducros F, Comte P, Lesieur M (1996) Large-eddy simulation of transition to turbulence in a boundary layer developing spatially over a flat plate. J Fluid Mech 326:1–36CrossRefGoogle Scholar
  6. Fairall CW, Bradley EF, Rogers DP, Edson JB, Young GS (1996) Bulk parameterization of air-sea fluxes for tropical ocean-global atmospheric coupled-ocean atmosphere response experiment. J Geophys Res 101:3747–3764CrossRefGoogle Scholar
  7. Garratt JR (1990) The internal boundary layer–a review. Boundary-Layer Meteorol 50:171–203CrossRefGoogle Scholar
  8. Lindzen R, Nigam S (1987) On the role of sea surface temperature gradients in forcing low-level winds and convergence in the Tropics. J Atmos Sci 44:2418–2436CrossRefGoogle Scholar
  9. Liu WT, Xie X, Polito P, Xie S-P, Hashizume H (2000) Atmospheric manifestation of tropical instability waves observed by QuikSCAT and Tropical Rain Measuring Mission. Geophys Res Lett 27:2545–2548CrossRefGoogle Scholar
  10. Louis J-F (1979) A parametric model of vertical eddy fluxes in the atmosphere. Boundary-Layer Meteorol 17:187–202CrossRefGoogle Scholar
  11. Mahrt L, Vickers D, Sun J, Crawford T, Crescenti G, Frederickson P (2001) Surface stress in offshore flow and quasi-frictional decoupling. J Geophys Res 106:20, 629–20, 639Google Scholar
  12. Mahrt L, Vickers D, Moore E (2004) Flow adjustments across sea-surface temperature changes. Boundary-Layer Meteorol 111:553–564CrossRefGoogle Scholar
  13. Mayor SD, Spalart PR, Tripoli GJ (2002) Application of a perturbation recycling method in the large-eddy simulation of a mesoscale convective internal boundary layer. J Atmos Sci 59:2385–2395CrossRefGoogle Scholar
  14. Nakamura R, Mahrt L (2005) A study of intermittent nocturnal turbulence with CASES-99 tower measurements. Boundary-Layer Meteorol 114:367–387CrossRefGoogle Scholar
  15. O’Neill L, Chelton D, Esbensen S (2003) Observations of SST-induced perturbations of the wind stress field over the Southern Ocean on seasonal timescales. J Climate 16:2340–2354CrossRefGoogle Scholar
  16. Samelson RM, Skyllingstad ED, Chelton DB, Esbensen SK, O’Neill LW, Thum N (2006) A note on the coupling of wind stress and sea surface temperature. J Climate 19:1557–1566CrossRefGoogle Scholar
  17. Skyllingstad ED (2003) Large-eddy simulation of katabatic flows. Boundary-Layer Meteorol 106:217–243CrossRefGoogle Scholar
  18. Skyllingstad E, Samelson R, Mahrt L, Barbour P (2005) A numerical modeling study of warm offshore flow over cool water. Mon Wea Rev 133:345–361CrossRefGoogle Scholar
  19. Smedman A-S, Bergström H, Grisogano B (1997) Evolution of stable internal boundary layers over a cold sea. J Geophys Res 102:1091–1099CrossRefGoogle Scholar
  20. Vickers D, Mahrt L, Sun J, Crawfordn T (2001) Structure of offshore flow. Mon Wea Rev 129:1251–1258CrossRefGoogle Scholar
  21. Vickers D, Mahrt L (2006) Evaluation of air-sea flux bulk formula and sea-surface temperature variability based on aircraft and tower observations. J Geophys Res 111, DOI:10.1029/2005JC003323Google Scholar
  22. Wallace J, Mitchell T, Deser C (1989) The influence of sea-surface temperature on surface wind in the eastern equatorial Pacific: seasonal and interannual variability. J Climate 2:1492–1499CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Eric D. Skyllingstad
    • 1
    Email author
  • Dean Vickers
    • 1
  • Larry Mahrt
    • 1
  • Roger Samelson
    • 1
  1. 1.College of Oceanic and Atmospheric SciencesOregon State UniversityCorvallisUSA

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