• 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, 14671488, doi:10.1029/JC092iC02p01467.

    • Search Google Scholar
    • Export Citation
  • Bellamy, J. C., 1945: The use of pressure altitude and altimeter corrections in meteorology. J. Meteor., 2, 178, doi:10.1175/1520-0469(1945)002<0001:TUOPAA>2.0.CO;2.

    • 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, doi:10.1175/1520-0493(1996)124<0668:TSLLJA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Burk, S. D., and W. T. Thompson, 1997: Mesoscale modeling of summertime refractive conditions in the Southern California Bight. J. Appl. Meteor., 36, 2231, doi:10.1175/1520-0450(1997)036<0022:MMOSRC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Dorman, C. E., 1985: Evidence of Kelvin waves in California’s marine layer and related eddy generation. Mon. Wea. Rev., 113, 827839, doi:10.1175/1520-0493(1985)113<0827:EOKWIC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Dorman, C. E., and D. Koračin, 2008: Response of the summer marine layer flow to an extreme California coastal bend. Mon. Wea. Rev., 136, 28942922, doi:10.1175/2007MWR2336.1.

    • Search Google Scholar
    • Export Citation
  • Dorman, C. E., D. P. Rogers, W. Nuss, and W. T. Thompson, 1999: Adjustment of the summer marine boundary layer around Point Sur, California. Mon. Wea. Rev., 127, 21432159, doi:10.1175/1520-0493(1999)127<2143:AOTSMB>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Haack, T., and S. D. Burk, 2001: Summertime marine refractivity conditions along coastal California. J. Appl. Meteor., 40, 673687, doi:10.1175/1520-0450(2001)040<0673:SMRCAC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Haack, T., S. D. Burk, C. Dorman, and D. Rodgers, 2001: Supercritical flow interaction within the Cape Blanco–Cape Mendocino orographic complex. Mon. Wea. Rev., 129, 688708, doi:10.1175/1520-0493(2001)129<0688:SFIWTC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Koračin, D., and C. E. Dorman, 2001: Marine atmospheric boundary divergence and clouds along California in June 1996. Mon. Wea. Rev., 129, 20402056, doi:10.1175/1520-0493(2001)129<2040:MABLDA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Parish, T. R., and D. Leon, 2013: Measurement of cloud perturbation pressures using an instrumented aircraft. J. Atmos. Oceanic Technol., 30, 215229, doi:10.1175/JTECH-D-12-00011.1.

    • Search Google Scholar
    • Export Citation
  • Parish, T. R., D. A. Rahn, and D. Leon, 2014: Aircraft observations of the marine layer adjustment near Point Arguello, California. J. Appl. Meteor. Climatol., 53, 970989, doi:10.1175/JAMC-D-13-0164.1.

    • Search Google Scholar
    • Export Citation
  • Parish, T. R., D. A. Rahn, and D. Leon, 2016: Research aircraft determination of D-value cross sections. J. Atmos. Oceanic Technol., 33, 391396, doi:10.1175/JTECH-D-15-0173.1.

    • Search Google Scholar
    • Export Citation
  • Rahn, D. A., T. R. Parish, and D. Leon, 2014: Coastal jet transition adjustment near Point Conception, California, with opposing wind in the bight. Mon. Wea. Rev., 142, 13441360, doi:10.1175/MWR-D-13-00177.1.

    • Search Google Scholar
    • Export Citation
  • Rodi, A. R., and D. C. Leon, 2012: Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements. Atmos. Meas. Tech., 5, 25692579, doi:10.5194/amt-5-2569-2012.

    • Search Google Scholar
    • Export Citation
  • Rogerson, A. M., 1999: Transcritical flows in the coastal marine atmospheric boundary layer. J. Atmos. Sci., 56, 27612779, doi:10.1175/1520-0469(1999)056<2761:TFITCM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Samelson, R. M., 1992: Supercritical marine-layer flow along a smoothly varying coastline. J. Atmos. Sci., 49, 15711584, doi:10.1175/1520-0469(1992)049<1571:SMLFAA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Skamarock, W. C., and Coauthors, 2008: A description of the Advanced Research WRF version 3. NCAR Tech. Note NCAR/TN-475+STR, 113 pp., doi:10.5065/D68S4MVH.

  • Wang, Z., P. Wechsler, W. Kuestner, J. French, A. R. Rodi, B. Glover, M. Burkhart, and D. Lukens, 2009: Wyoming Cloud Lidar: Instrument description and applications. Opt. Express, 17, 13 57613 587, doi:10.1364/OE.17.013576.

    • Search Google Scholar
    • Export Citation
  • Wang, Z., J. French, G. Vali, and P. Wechsler, 2012: Single aircraft integration of remote sensing and in situ sampling for the study of cloud microphysics and dynamics. Bull. Amer. Meteor. Soc., 93, 653668, doi:10.1175/BAMS-D-11-00044.1.

    • Search Google Scholar
    • Export Citation
  • Winant, C. D., C. E. Dorman, C. A. Friehe, and R. C. Beardsley, 1988: The marine boundary layer off northern California: An example of supercritical channel flow. J. Atmos. Sci., 45, 35883605, doi:10.1175/1520-0469(1988)045<3588:TMLONC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Zemba, J., and C. A. Friehe, 1987: The marine boundary layer jet in the Coastal Ocean Dynamics Experiment. J. Geophys. Res., 92, 14891496, doi:10.1029/JC092iC02p01489.

    • Search Google Scholar
    • Export Citation
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Aircraft Measurements and Numerical Simulations of an Expansion Fan off the California Coast

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  • 1 Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming
  • | 2 Department of Geography and Atmospheric Science, University of Kansas, Lawrence, Kansas
  • | 3 Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming
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Abstract

Mountains along the California coastline play a critical role in the dynamics of marine atmospheric boundary layer (MBL) airflow in the vicinity of the shoreline. Large changes in the MBL topology have been known to occur downwind of points and capes along the western coast of the United States. Large spatial gradients in wind and temperature become established that can cause anomalous electromagnetic wave propagation. Detailed airborne measurements using the University of Wyoming King Air were conducted to study the adjustment of the MBL to the Point Arguello and Point Conception headlands. Pronounced thinning of the MBL consistent with an expansion fan occurred to the south of Point Conception on 13 June 2012. A sharp cloud edge was collocated with the near collapse of the MBL. D-value cross sections derived from differential GPS altitude measurements allow assessment of the vertical profile of the horizontal pressure gradient force and hence thermal wind forcing in response to the near collapse of the MBL. The Weather Research and Forecasting Model was run with a 1-km grid spacing to examine the atmospheric adjustment around Point Conception during this period. Results from the simulations including the vertical cross sections of the horizontal pressure gradient force were consistent with the aircraft observations. Model results suggest that divergence occurs as the flow rounds Point Conception, characteristic of an expansion fan. Wind speeds in the MBL increase coincident with the decrease in MBL thickness, and subsiding flow associated with the near collapse of the MBL is responsible for the sharp cloud edge.

Corresponding author address: Thomas R. Parish, Department of Atmospheric Science, University of Wyoming, Laramie, WY 82071. E-mail: parish@uwyo.edu

Abstract

Mountains along the California coastline play a critical role in the dynamics of marine atmospheric boundary layer (MBL) airflow in the vicinity of the shoreline. Large changes in the MBL topology have been known to occur downwind of points and capes along the western coast of the United States. Large spatial gradients in wind and temperature become established that can cause anomalous electromagnetic wave propagation. Detailed airborne measurements using the University of Wyoming King Air were conducted to study the adjustment of the MBL to the Point Arguello and Point Conception headlands. Pronounced thinning of the MBL consistent with an expansion fan occurred to the south of Point Conception on 13 June 2012. A sharp cloud edge was collocated with the near collapse of the MBL. D-value cross sections derived from differential GPS altitude measurements allow assessment of the vertical profile of the horizontal pressure gradient force and hence thermal wind forcing in response to the near collapse of the MBL. The Weather Research and Forecasting Model was run with a 1-km grid spacing to examine the atmospheric adjustment around Point Conception during this period. Results from the simulations including the vertical cross sections of the horizontal pressure gradient force were consistent with the aircraft observations. Model results suggest that divergence occurs as the flow rounds Point Conception, characteristic of an expansion fan. Wind speeds in the MBL increase coincident with the decrease in MBL thickness, and subsiding flow associated with the near collapse of the MBL is responsible for the sharp cloud edge.

Corresponding author address: Thomas R. Parish, Department of Atmospheric Science, University of Wyoming, Laramie, WY 82071. E-mail: parish@uwyo.edu
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