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Tjernström, Michael (2011)
Publisher: Co-Action Publishing
Journal: Tellus A
Languages: English
Types: Article
Hypothetical numerical simulations are carried out to investigate the sensitivity of a coastallytrappedsupercritical flow to various forcing. All simulations are compared with a controlsimulation, that is based on a real case from the coastal waves field experiment off the coast ofCalifornia in 1996, the 7 June case. This case features a northerly supercritical flow along theCalifornia coast that triggers an expansion fan at Cape Mendocino (40.4°N, 124.4°W). Theupstream jet then strengthens as the boundary layer becomes more shallow. Other importantfeatures are the terrain at the cape and the SST depression into Shelter Cove in the lee of thecape. All sensitivity simulations reveal an expansion fan with the associated dynamics; thisappears to be a very stable feature. Altering the local terrain changes the local structure of thejet and removes the lee-wave that is responsible for the apparent collapse of the boundary layerin Shelter Cove. A realistic SST, instead of a spatially constant value, has only minor effectsvery locally. Changing the Froude number of the flow by manipulation of the inversion strengthreveals an unexpected feedback. A weaker inversion increases the entrainment and thus deepensthe boundary layer, and vice versa, while increasing the inversion strength. In the expressionfor the Froude number, these 2 effects cancel and the end results is very similar to the controlrun. Even when reducing the background flow speed by 50%, an expansion fan appeared. Thiscase is thus transcritical–subcritical upstream, turning supercritical at the cape. It experiencesthe largest changes in terms of wind speed. Attempts to generate a solid stratocumulus layer(no clouds were present in reality) in the model failed. Within a realistic increase of the initialboundary layer humidity, it was not possible to maintain clouds in these runs. In summary,the expansion fan dynamics appear strong and quite consistent, and it was virtually impossibleto find a set of conditions, based on perturbations to the control case, that did not revealsupercriticality and the expansion fan dynamics.DOI: 10.1034/j.1600-0870.1999.00023.x
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    • Andre´n, A. 1990. Evaluation of a turbulence closure scheme suitable for air-pollution applications. J. Appl. Meteor 29, 224-239.
    • Baines, P. G. 1995. T opographic eVects in stratified flow. Cambridge University Press, pp. 88-90.
    • Beardsley, R. C., Dorman, C. E., Friehe, C. A., Rosenfeld, L. K. and Winant, C. D. 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, 1467-1488.
    • Bond, N. A., Mass, C. F. and Overland, J. E. 1996. Coastally trapped wind reversals along the UnitedStates west coast during the warm-season (1) Climatology and temporal evolution. Mon. Wea. Rev. 124, 430-445.
    • Burk, S. D. and Thompson, W. T. 1996. The summertime low-level jet and marine boundary-layer structure along the california coast. Mon. Wea. Rev. 124, 668-686.
    • Burk, S. D. and Haack, T. 1998. Modeling unusual coastal wave clouds. Preprint. 8th Conference on Mountain meteorology, FlagstaV, AZ. Amer. Meteor. Soc.
    • Brooks, I. M. and Rogers, D. P. 1997. Aircraft observations of boundary layer rolls of the coast of California. J. Atmos. Sci. 54, 1834-1849.
    • Cui, Z., Tjernstr o¨m, M. and Grisogono, B. 1998. Idealized simulations of atmospheric coastal flow along the central coast of California. J. Appl. Meteor. 37, 1332-1363.
    • Dorman, C. E. and Winant, C. D. 1995. Buoy observations of the atmosphere along the west coast of the United-States, 1981-1990. J. Geophys. Res. 100, 16029-16044.
    • Dorman, C. E. and Rogers, D. P. 1998. The structure of summer high wind speeds around Cape Mendocino, California. Preprints. 2nd Conference on Coastal atmospheric and oceanic prediction and processes, Phoenix, AZ. Amer. Meteor. Soc., p. 156.
    • Dorman, C. E., Rogers, D. P., Nuss, W. and Thompson, W. T. 1999a. Adjustment of the summer marine boundary layer around Pt. Sur, California. Mon. Wea. Rev., in press.
    • Dorman, C. E., Holt, T., Rogers, D. P. and Edwards, K. 1999b. Large-scale structure of the June-July 1996 marine boundary layer along California and Oregon. Mon. Wea. Rev., in press.
    • Enger, L. 1986. A higher order closure model applied to dispersion in a convective PBL. Atmos. Environ. 20, 879-894.
    • Enger, L. 1990a. Simulation of dispersion in moderately complex terrain - Part A. The fluid dynamic model. Atmos. Environ. 24A, 2431-2446.
    • Enger, L. 1990b. Simulation of dispersion in moderately complex terrain - Part B. The higher order closure dispersion model. Atmos. Environ. 24A, 2447-2455.
    • Enger, L., Koracin, D. and Yang, X. 1993. A numerical study of the boundary layer dynamics in a mountain valley. Part 1. Model validation and sensitivity experiments. Bound. L ayer Meteor. 66, 357-394.
    • Enger, L. and Grisogono, B. 1998. The response of Boratype flow to sea-surface temperature, Quart. J. Roy. Meteor. Soc. 124, 1227-1244.
    • Grisogono, B. 1995. Wave drag eVects in a mesoscale model with a higher order closure turbulence scheme. J. Appl. Meteor. 34, 941-954.
    • Grisogono, B. and Tjernstr o¨m, M. 1996. Thermal mesoscale circulations on the Baltic coast (2) Perturbation of surface parameters. J. Geophys. Res. 101, D14, 18,999-19,012.
    • Grisogono, B., Str o¨m, L. and Tjernstr o¨m, M. 1998. Small-scale variability in the coastal atmospheric boundary layer. Bound-L ayer Meteor. 88, 23-46.
    • Mellor, G. L. and Yamada, T. 1982. Development of a closure model of geophysical flows. Reviews of Geophysics and Space Physics 20, 851-875.
    • Neiburger, M., Johnson, D. S. and Chien, C. W. 1961. Studies of the structure of the atmosphere over the eastern Pacific Ocean in the summer. In: T he inversion over the eastern north Pacific Ocean, University of California Press, pp. 1-94.
    • Overland, J. E. 1984. Scale analysis of marine winds in straits and along mountainous coasts. Mon. Wea. Rev. 112, 2532-2536.
    • Pielke, R. A. 1984. Mesoscale meteorological modeling. Academic Press, 599 pp.
    • Rogers, D., Dorman, C. E., Edwards, K., Brooks, I., Melville, K., Burk, S. D., Thompson, W. T., Holt, T., Str o¨m, L., Tjernstr o¨m, M., Grisogono, B., Bane, J. M., Nuss, W., Morley, B. and Schanot, A. 1998. Highlights of coastal waves 1996, Bull. Am. Meteorol. Soc. 79, 1307-1326.
    • Samelson, R. M. 1992. Super-critical marine-layer flow along a smoothly varying coastline. J. Atmos. Sci., 49, 1571-1584.
    • Samelson, R. M. and Lentz, S. J. 1994. The horizontal momentum balance in the marine atmospheric boundary layer during CODE-2. J. Atmos.Sci. 51, 3745-3757.
    • Svensson, G. 1998. Model simulations of the air quality in Athens, Greece, during the MEDCAPHOTTRACE Campaign. Atmos. Env. 52, 2239-2268.
    • Svensson, G. and Klemm, O. 1998. Aircraft measurements and model simulations of the air quality in Athens, Greece. Atmos. Env. 52, 2269-2289.
    • Tjernstr o¨m, M. 1987a. A study of flow over complex terrain using a three-dimensional model. A preliminary model evaluation focusing on stratus and fog. Ann. Geophys. 88, 469-486.
    • Tjernstr o¨m, M. 1987b. A 3-dimensional meso-c-scale model for studies of stratiform boundary layer clouds. A model description. Department of Meteorology, Uppsala University, Rep. no 85.
    • Tjernstr o¨m, M. 1988a. Numerical simulations of stratiform boundary-layer clouds on the meso-c-scale. Part I. The influence of terrain height diVerences. Bound. L ayer Meteor. 44, 33-72.
    • Tjernstr o¨m, M. 1988b. Numerical simulations of stratiform boundary-layer clouds on the meso-c-scale. Part II. The influence of a step change in surface roughness and surface temperature. Bound. L ayer Meteor. 44, 307-230.
    • Tjernstr o¨m, M. and Koracin, D. 1995. Modelling the impact of stratocumulus on boundary layer structure. J. Atmos. Sci. 52, 863-878.
    • Tjernstr o¨m, M. and Rogers, D. P. 1996. Turbulence Structure in Decoupled Marine Stratocumulus: A case study from the Astex field experiment. Journal of Atmospheric Sciences, 53, 598-619.
    • Tjernstr o¨m, M. and Grisogono, B. 1996. Thermal mesoscale circulations on the Baltic coast (1) A numerical case study. J. Geophys. Res. 101, D14, 18,979-18,997.
    • Tjernstr o¨m, M. and Grisogono, B. 1999. Simulations of super-critical flow around points and capes in a coastal atmosphere. J. Atmos. Sci., in press.
    • Winant, C. D., Dorman, C. E., Friehe, C. A. and Beardsley, R. C. 1988. The marine layer oV northern California - an example of supercritical channel flow. J. Atmos. Sci. 45, 3588-3605.
    • Zemba, J. and Friehe, C. A. 1987. The marine atmospheric boundary-layer jet in the coastal ocean dynamics experiment. J. Geophys. Res. 92, 1489-1496.
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