• Baines, P. G., 1995: Topographic Effects in Stratified Flows. Cambridge University Press, 482 pp. .

  • Brost, R. A., J. C. Wyngaard, and D. H. Lenschow, 1982: Marine stratocumulus layers. Part II: Turbulence budgets. J. Atmos. Sci., 39 , 818836.

    • Search Google Scholar
    • Export Citation
  • Burk, S. D., and W. T. Thompson, 1996: The summertime low-level jet and marine boundary layer structure along the California coast. Mon. Wea. Rev., 124 , 668686.

    • Search Google Scholar
    • Export Citation
  • ——, Haack, T., and R. M. Samelson, 1999: Mesoscale simulation of supercritical, subcritical, and transcritical flow along coastal topography. J. Atmos. Sci., 56 , 27802795.

    • Search Google Scholar
    • Export Citation
  • Casey, K. S., and P. Cornillon, 1999: A comparison of satellite and in situ based sea surface temperature climatologies. J. Climate, 12 , 18481863.

    • Search Google Scholar
    • Export Citation
  • Davidson, K. L., P. J. Boyle, and P. S. Guest, 1992: Atmospheric boundary-layer properties affecting wind forecasting in coastal regions. J. Appl. Meteor., 31 , 983994.

    • Search Google Scholar
    • Export Citation
  • Dorman, C. E., 1985: Hydraulic control of the Northern California marine layer. Proc. December 1985 Annual Meeting, San Francisco, CA, Amer. Geophys. Union, EOS, 66, 914.

    • Search Google Scholar
    • Export Citation
  • ——, Rogers, D. P., W. Nuss, and W. T. Thompson, 1999: Adjustment of the summer marine boundary layer around Pt. Sur, California. Mon. Wea. Rev., 127 , 21432159.

    • Search Google Scholar
    • Export Citation
  • ——, Holt, T., and K. A. Edwards, 2000: Large-scale structure of the summertime marine boundary layer along Oregon and California. Mon. Wea. Rev., 128 , 16321652.

    • Search Google Scholar
    • Export Citation
  • Edwards, K. A., and C. D. Winant, 1999: Vertical structure of the marine atmospheric boundary layer. Proc. Fifth California Islands Symp. Santa Barbara, CA, Minerals Management Service, p. 23.

    • Search Google Scholar
    • Export Citation
  • Enriquez, A. G., and C. A. Friehe, 1995: Effects of wind stress and wind stress curl variability on coastal upwelling. J. Phys. Oceanogr., 25 , 16511671.

    • Search Google Scholar
    • Export Citation
  • ——, and ——,. 1997: Bulk parameterization of momentum, heat, and moisture fluxes over a coastal upwelling area. J. Geophys. Res., 102 , 57815798.

    • Search Google Scholar
    • Export Citation
  • Finnigan, T. D., S. E. Allen, and G. A. Lawrence, 1998: Physical modeling of an outflow event in Howe Sound, British Columbia. J. Geophys. Res., 103 , 39373950.

    • Search Google Scholar
    • Export Citation
  • Freeman, J. C,Jr, 1950: The wind field of the equatorial East Pacific as a Prandtl-Meyer expansion. Bull. Amer. Meteor. Soc., 31 , 303304.

    • Search Google Scholar
    • Export Citation
  • ——,. 1951: The solution of nonlinear meteorological problems by the method of characteristics. Compendium of Meteorology, T. F. Malone, Ed., Amer. Meteor. Soc., 421–433.

    • Search Google Scholar
    • Export Citation
  • Henderson, F. M., 1966: Open Channel Flow. The Macmillan Company, 522 pp.

  • Ippen, A. T., 1951: Mechanics of supercritical flow. Trans. Amer. Soc. Civ. Eng., 116 , 268295.

  • Jackson, P., and D. G. Steyn, 1994: Gap winds in a fjord. Part II: Hydraulic analog. Mon. Wea. Rev., 122 , 26662676.

  • Koracin, D., and C. E. Dorman, 2001: Marine atmospheric boundary layer divergence and clouds along California in June 1996. Mon. Wea. Rev., in press.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., and S. Pond, 1981: Open ocean momentum flux in moderate to strong winds. J. Phys. Oceanogr., 11 , 324336.

  • Lester, P. F., 1985: Studies of the marine inversion over the San Francisco Bay area: A summary of the work of Albert Miller, 1961–1978. Bull. Amer. Meteor. Soc., 66 , 13961402.

    • Search Google Scholar
    • Export Citation
  • Liepmann, H. W., and A. Roshko, 1957: Elements of Gas Dynamics. Wiley, 439 pp.

  • Liu, W. T., K. B. Katsaros, and J. A. Businger, 1979: Bulk parameterization of air–sea exchanges of heat and water vapor including the molecular constraints at the interface. J. Atmos. Sci., 36 , 17221735.

    • Search Google Scholar
    • Export Citation
  • Monin, A. S., and A. M. Obukhov, 1957: Basic Regularity in Turbulent Mixing in the Atmosphere. Vol. 24, Works of the Geophysical Institute, U.S.S.R. Academy of Science, 28 pp.

    • Search Google Scholar
    • Export Citation
  • Morley, B. M., K. K. Laursen, L. F. Radke, and A. D. Clarke, 1996: Early results from the Aerosol Characterization Experiment 1 using airborne lidar and in situ aerosol sampling. Proc. Second Int. Airborne Sensing Conf. and Exhibition, San Francisco, CA, Environmental Research Institute of Michigan, Vol. I, 40–48.

    • Search Google Scholar
    • Export Citation
  • Neiburger, M., D. S. Johnson, and C-W. Chien, 1961: Studies of the Structure of the Atmosphere over the Eastern Pacific Ocean in Summer. Vol. 1, University of California Publications in Meteorology, University of California Press, 58 pp.

    • Search Google Scholar
    • Export Citation
  • Nelson, C. S., 1977: Wind stress and wind stress curl over the California current. NOAA Tech. Rep. 714, 87 pp.

  • Rogerson, A. M., 1999a: Transcritical flows in the coastal marine atmospheric boundary layer. J. Atmos. Sci., 56 , 27612779.

  • ——,. 1999b: A shallow-water model for hydraulically transcritical flows. Tech. Rep. WHOI-99-09, Woods Hole Oceanographic Institution, Woods Hole, MA, 50 pp.

    • Search Google Scholar
    • Export Citation
  • Ruth, R., 1998: The NCAR/NSF EC-130 Hercules (N130AR): Overview and summary of capabilities. NCAR RAF Bulletin No. 3, 19 pp. [Available from National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307.].

    • Search Google Scholar
    • Export Citation
  • Samelson, R. M., 1992: Supercritical marine-layer flow along a smoothly varying coastline. J. Atmos. Sci., 49 , 15711584.

  • ——, and Lentz, S. J., 1994: The horizontal momentum balance in the marine atmospheric boundary layer during CODE-2. J. Atmos. Sci., 51 , 37453757.

    • Search Google Scholar
    • Export Citation
  • Scorer, R. S., 1949: Theory of waves in the lee of mountains. Quart. J. Roy. Meteor. Soc., 75 , 4156.

  • Shapiro, A. H., 1953: The Dynamics and Thermodynamics of Compressible Flow, I and II. The Ronald Press Company, 293 pp.

  • Shu, C. W., and S. Osher, 1988: Efficient implementation of ENO schemes I. J. Comput. Phys., 77 , 439471.

  • ——, and ——,. 1989: Efficient implementation of ENO schemes II. J. Comput. Phys., 83 , 3278.

  • Smith, S. D., 1980: Wind stress and heat flux over the ocean in gale force winds. J. Phys. Oceanogr., 10 , 709726.

  • ——, and Coauthors. 1992: Sea surface wind stress and drag coefficients: The HEXOS results. Bound.-Layer Meteor., 60 , 109142.

  • Ström, L., D. P. Rogers, and I. M. Brooks, 1997: Turbulence in the stably stratified marine boundary layer observed during the Coastal Waves experiment 1996. Preprints, 12th Symp. on Boundary Layers and Turbulence, Vancouver, BC, Canada, Amer. Meteor. Soc., 136–137.

    • Search Google Scholar
    • Export Citation
  • ——, Tjernström, M., and D. Rogers, 2001: Observed dynamics of coastal flow at Cape Mendocino during Coastal Waves 1996. J. Atmos.Sci., 58 , 953977.

    • Search Google Scholar
    • Export Citation
  • Tjernström, M., 1999: The sensitivity of supercritical atmospheric boundary layer flow along a coastal mountain barrier. Tellus, 51A , 880901.

    • Search Google Scholar
    • Export Citation
  • ——, and Grisogono, B., 2000: Simulations of supercritical flow around points and capes in a coastal atmosphere. J. Atmos. Sci., 57 , 108135.

    • Search Google Scholar
    • Export Citation
  • Wentz, F. J., 1997: A well-calibrated ocean algorithm for special sensor microwave/imager. J. Geophys. Res., 102 , 87038718.

  • Winant, C. D., C. E. Dorman, C. A. Friehe, and R. Beardsley, 1988: The marine layer off northern California: An example of supercritical channel flow. J. Atmos. Sci., 45 , 35883605.

    • Search Google Scholar
    • Export Citation
  • Yelland, M., and P. K. Taylor, 1996: Wind stress measurements from the open ocean. J. Phys. Oceanogr., 26 , 87038718.

  • Zemba, J., and C. A. Friehe, 1987: The marine atmospheric boundary layer jet during the Coastal Ocean Dynamics Experiment. J. Geophys. Res., 92 , 14891496.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 150 23 2
PDF Downloads 54 16 1

Adjustment of the Marine Atmospheric Boundary Layer to a Coastal Cape

Kathleen A. EdwardsSchool of Oceanography, University of Washington, Seattle, Washington

Search for other papers by Kathleen A. Edwards in
Current site
Google Scholar
PubMed
Close
,
Audrey M. RogersonWoods Hole Oceanographic Institution, Woods Hole, Massachusetts

Search for other papers by Audrey M. Rogerson in
Current site
Google Scholar
PubMed
Close
,
Clinton D. WinantScripps Institution of Oceanography, La Jolla, California

Search for other papers by Clinton D. Winant in
Current site
Google Scholar
PubMed
Close
, and
David P. RogersScripps Institution of Oceanography, La Jolla, California

Search for other papers by David P. Rogers in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

During summer, significant changes in marine atmospheric boundary layer (MABL) speed and depth occur over small spatial scales (<100 km) downstream from topographic features along the California coast. In June and July 1996, the Coastal Waves 96 project collected observations of such changes at capes with an instrumented aircraft. This paper presents observations from the 7 June flight, when the layer-averaged speed increased 9 m s−1 and depth decreased by 500 m over a 75-km downwind from Cape Mendocino, accompanied by enhanced surface fluxes and local cloud clearing. The acceleration and thinning are reproduced when the flow is modeled as a shallow transcritical layer of fluid impinging the bends of a coastal wall, leading to the interpretation that they are produced by an expansion fan. Model runs were produced with different coastlines and imposed pressure gradients, with the best match provided by a coastline in which the cape protruded into the flow and forced a response in the subcritical region upstream of the cape. A hydraulic jump was produced at a second bend, near where the aircraft's lidar observed the MABL height to increase. Light variable winds observed within Shelter Cove were replicated in model flows in which the flow separated from the coastline. Though highly idealized, the shallow-water model provided a satisfactory representation of the main features of the observed flow.

*Current affiliation: Office of Weather and Air Quality Research, NOAA/OAR, Silver Spring, Maryland.

Corresponding author address: Kathleen A. Edwards, School of Oceanography, University of Washington, Seattle, WA 98195-7540.Email: kate@ocean.washington.edu

Abstract

During summer, significant changes in marine atmospheric boundary layer (MABL) speed and depth occur over small spatial scales (<100 km) downstream from topographic features along the California coast. In June and July 1996, the Coastal Waves 96 project collected observations of such changes at capes with an instrumented aircraft. This paper presents observations from the 7 June flight, when the layer-averaged speed increased 9 m s−1 and depth decreased by 500 m over a 75-km downwind from Cape Mendocino, accompanied by enhanced surface fluxes and local cloud clearing. The acceleration and thinning are reproduced when the flow is modeled as a shallow transcritical layer of fluid impinging the bends of a coastal wall, leading to the interpretation that they are produced by an expansion fan. Model runs were produced with different coastlines and imposed pressure gradients, with the best match provided by a coastline in which the cape protruded into the flow and forced a response in the subcritical region upstream of the cape. A hydraulic jump was produced at a second bend, near where the aircraft's lidar observed the MABL height to increase. Light variable winds observed within Shelter Cove were replicated in model flows in which the flow separated from the coastline. Though highly idealized, the shallow-water model provided a satisfactory representation of the main features of the observed flow.

*Current affiliation: Office of Weather and Air Quality Research, NOAA/OAR, Silver Spring, Maryland.

Corresponding author address: Kathleen A. Edwards, School of Oceanography, University of Washington, Seattle, WA 98195-7540.Email: kate@ocean.washington.edu

Save