Editorial Type:
Article
Article Type:
Research Article

Transcritical Flows in the Coastal Marine Atmospheric Boundary Layer

A. M. Rogerson Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

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Print Publication:
01 Aug 1999
DOI:
https://doi.org/10.1175/1520-0469(1999)056<2761:TFITCM>2.0.CO;2
Page(s):
2761–2779
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Abstract

Numerical solutions of shallow water flow in a variable-width channel are computed to model the summertime marine atmospheric boundary layer off the U.S. west coast. Using an idealization of the coastline in the vicinity of Point Arena, California, as an example, several steady-state base flows are presented that are hydraulically transcritical. These flows are strongly nonlinear, weakly rotational, and are forced by constant pressure gradients and damped by nonlinear bottom drag at the sea surface. The transcritical base flows are supercritical in the vicinity of bends in the coastline but are subcritical to the north (upstream) and to the south (downstream) where the coastline is straight. Within the supercritical region, orographic bends in the coastline produce expansion fans and compression jumps, the same structures found in globally supercritical flows. When the imposed pressure-gradient forcing is increased, the resulting base flow has a supercritical-to-subcritical transitional jump that is weaker and located farther downstream, increasing the extent of the supercritical region. Perturbations are applied to the transcritical base flows in the south to study the interaction of coastal-trapped disturbances with the base flows. The disturbances propagate northward in the subcritical region of the base flow but can be halted after they reach the supercritical region. Very strong nonlinear disturbances can overcome the supercriticality of the base flow and propagate all the way up the coast but are severely attenuated in the process. The interaction of strong coastal-trapped disturbances with the transcritical base flows is accompanied by an eddy-generation process that resembles satellite images of stratus observed during the May 1982 coastal-trapped event off California.

Corresponding author address: Audrey Rogerson, MS #21, Room 304A, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1541.

Abstract

Numerical solutions of shallow water flow in a variable-width channel are computed to model the summertime marine atmospheric boundary layer off the U.S. west coast. Using an idealization of the coastline in the vicinity of Point Arena, California, as an example, several steady-state base flows are presented that are hydraulically transcritical. These flows are strongly nonlinear, weakly rotational, and are forced by constant pressure gradients and damped by nonlinear bottom drag at the sea surface. The transcritical base flows are supercritical in the vicinity of bends in the coastline but are subcritical to the north (upstream) and to the south (downstream) where the coastline is straight. Within the supercritical region, orographic bends in the coastline produce expansion fans and compression jumps, the same structures found in globally supercritical flows. When the imposed pressure-gradient forcing is increased, the resulting base flow has a supercritical-to-subcritical transitional jump that is weaker and located farther downstream, increasing the extent of the supercritical region. Perturbations are applied to the transcritical base flows in the south to study the interaction of coastal-trapped disturbances with the base flows. The disturbances propagate northward in the subcritical region of the base flow but can be halted after they reach the supercritical region. Very strong nonlinear disturbances can overcome the supercriticality of the base flow and propagate all the way up the coast but are severely attenuated in the process. The interaction of strong coastal-trapped disturbances with the transcritical base flows is accompanied by an eddy-generation process that resembles satellite images of stratus observed during the May 1982 coastal-trapped event off California.

Corresponding author address: Audrey Rogerson, MS #21, Room 304A, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1541.

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  • Bannon, P. R., 1981: Synoptic-scale forcing of coastal lows: Forced double Kelvin waves in the atmosphere. Quart. J. Roy. Meteor. Soc.,107, 313–327.

  • Batchelor, G. K., 1967: An Introduction to Fluid Dynamics. Cambridge University Press, 615 pp.

  • Beardsley, R. C., C. E. Dorman, C. A. Friehe, L. K. Rosenfeld, and C. D. Winant, 1987: Local atmospheric forcing during the Coastal Ocean Dynamics Experiment: 1. A description of the marine boundary layer and atmospheric conditions over a northern California upwelling region. J. Geophys. Res.,92 (C2), 1467–1488.

  • Bond, N. A., C. F. Mass, and J. E. Overland, 1996: Coastally trapped wind reversals along the United States west coast during the warm season. Part I: Climatology and temporal evolution. Mon. Wea. Rev.,124, 430–445.

  • Dorman, C. E., 1985a: Hydraulic control of the northern California marine layer (abstract). Eos, Trans. Amer. Geophys. Union,66, 914.

  • ——, 1985b: Evidence of Kelvin waves in California’s marine layer and related eddy generation. Mon. Wea. Rev.,113, 827–839.

  • ——, 1987: Possible role of gravity currents in northern California’s coastal summer wind reversals. J. Geophys. Res.,92 (C2), 1497–1506.

  • ——, 1988: Comments on “Coastal southerlies and alongshore surges of the west coast of North America: Evidence of mesoscale topographically trapped response to synoptic forcing.” Mon. Wea. Rev.,116, 2401–2406.

  • ——, 1997: Comments on “Coastally trapped wind reversals along the United States west coast during the warm season. Part II: Synoptic evolution.” Mon. Wea. Rev.,125, 1692–1694.

  • Drazin, P. G., and W. H. Reid, 1981: Hydrodynamic Stability. Cambridge University Press, 527 pp.

  • Enriquez, A. G., and C. A. Friehe, 1995: Effects of wind stress and wind stress curl variability on coastal upwelling. J. Phys. Oceanogr.,25, 1651–1671.

  • Gill, A. E., 1977: Coastally trapped waves in the atmosphere. Quart. J. Roy. Meteor. Soc.,103, 431–440.

  • Hermann, A. J., B. M. Hickey, C. F. Mass, and M. D. Albright, 1990:Orographically trapped coastal wind events in the Pacific Northwest and their oceanic response. J. Geophys. Res.,95 (C8), 13 169–13 193.

  • Holland, G. J., and L. M. Leslie, 1986: Ducted coastal ridging over S.E. Australia. Quart. J. Roy. Meteor. Soc.,112, 731–748.

  • Klemp, J. B., R. Rotunno, and W. C. Skamarock, 1995: Shallow-water model simulations of coastally trapped disturbances. Preprints, Seventh Conf. on Mountain Meteorology, Breckenridge, CO, Amer. Meteor. Soc., 197–202.

  • ——, ——, and ——, 1997: On the propagation of internal bores. J. Fluid Mech.,331, 81–106.

  • Large, W. G., and S. Pond, 1981: Open ocean momentum flux measurements in moderate to strong winds. J. Phys. Oceanogr.,11, 324–336.

  • Liepmann, H. W., and A: Roshko, 1957: Elements of Gasdynamics. John Wiley and Sons, 456 pp.

  • Mass, C. F., 1995: Comments on “The dynamics of coastally trapped mesoscale ridges in the lower atmosphere.” J. Atmos. Sci.,52, 2313–2318.

  • ——, and M. D. Albright, 1987: Coastal southerlies and alongshore surges of the west coast of North America: Evidence of mesoscale topographically trapped response to synoptic forcing. Mon. Wea. Rev.,115, 1707–1738.

  • ——, and ——, 1988: Reply. Mon. Wea. Rev.,116, 2407–2410.

  • ——, and N. A. Bond, 1996: Coastally trapped wind reversals along the United States west coast during the warm season. Part II: Synoptic evolution. Mon. Wea. Rev.,124, 446–461.

  • ——, and ——, 1997: Reply. Mon. Wea. Rev.,125, 1695–1697.

  • Neiburger, M., 1960: The relation of air mass structure to the field of motion over the eastern North Pacific Ocean in summer. Tellus,12, 31–40.

  • Nguyen, N. A., and A. E. Gill, 1981: Generation of coastal lows by synoptic-scale waves. Quart. J. Roy. Meteor. Soc.,107, 521–530.

  • Ralph, F. M., L. Armi, J. M. Bane, C. Dorman, W. D. Neff, P. J. Neiman, W. Nuss, and P. O. G. Persson, 1998: Observations and analysis of the 10–11 June 1994 coastally trapped disturbance. Mon. Wea. Rev.,126, 2435–2465.

  • Reason, C. J. C., and M. R. Jury, 1990: On the generation and propagation of the southern African coastal low. Quart. J. Roy. Meteor. Soc.,116, 1133–1151.

  • ——, and D. G. Steyn, 1992: The dynamics of coastally trapped mesoscale ridges in the lower atmosphere. J. Atmos. Sci.,49, 1677–1692.

  • ——, and ——, 1995: Reply. J. Atmos. Sci.,52, 2319–2324.

  • Roe, P. L., 1981: Approximate Riemann solvers, parameter vectors, and difference schemes. J. Comput. Phys.,43, 357–372.

  • Rogerson, A. M., and E. Meiburg, 1990: A numerical study of the convergence properties of ENO schemes. J. Sci. Comput.,5 (2), 151–167.

  • ——, and R. M. Samelson, 1995: Synoptic forcing of coastal-trapped disturbances in the marine atmospheric boundary layer. J. Atmos. Sci.,52, 2025–2040.

  • Samelson, R. M., 1992: Supercritical marine-layer flow along a smoothly varying coastline. J. Atmos. Sci.,49, 1571–1584.

  • ——, and S. J. Lentz, 1994: The horizontal momentum balance in the marine atmospheric boundary layer during CODE-2. J. Atmos. Sci.,51, 3745–3757.

  • ——, and A. M. Rogerson, 1996: Life cycle of a linear coastal-trapped disturbance. Mon. Wea. Rev.,124, 1853–1863.

  • Shu, C.-W., 1990: Numerical experiments on the accuracy of ENO and modified ENO schemes. J. Sci. Comput.,5 (2), 127–149.

  • ——, and S. Osher, 1988: Efficient implementation of essentially non-oscillatory shock-capturing schemes. J. Comput. Phys.,77 (2), 439–471.

  • ——, and ——, 1989: Efficient implementation of essentially non-oscillatory shock-capturing schemes, II. J. Comput. Phys.,83, 32–78.

  • Skamarock, W. C., J. B. Klemp, and R. Rotunno, 1996: The diffraction of Kelvin waves and bores at coastal bends. J. Atmos. Sci.,53, 1327–1337.

  • Stoker, J. J., 1957: Water Waves. Interscience, 567 pp.

  • Thompson, W. T., T. Haack, J. D. Doyle, and S. D. Burk, 1997: A nonhydrostatic mesoscale simulation of the 10–11 June 1994 coastally trapped wind reversal. Mon. Wea. Rev.,125, 3211–3230.

  • Winant, C. D., C. E. Dorman, C. A. Friehe, and R. C. Beardsley, 1988: The marine layer off northern California: An example of supercritical channel flow. J. Atmos. Sci.,45, 3588–3605.

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