Editorial Type:
Article
Article Type:
Research Article

Multiscale Mountain Waves Influencing a Major Orographic Precipitation Event

Matthew F. Garvert Department of Atmospheric Sciences, University of Washington, Seattle, Washington

Search for other papers by Matthew F. Garvert in
Current site
Google Scholar
PubMed Close
,
Bradley Smull Department of Atmospheric Sciences, University of Washington, Seattle, Washington

Search for other papers by Bradley Smull in
Current site
Google Scholar
PubMed Close
, and
Cliff Mass Department of Atmospheric Sciences, University of Washington, Seattle, Washington

Search for other papers by Cliff Mass in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Mar 2007
DOI:
https://doi.org/10.1175/JAS3876.1
Page(s):
711–737
Restricted access

We are aware of a technical issue preventing figures and tables from showing in some newly published articles in the full-text HTML view.
While we are resolving the problem, please use the online PDF version of these articles to view figures and tables.

Abstract

This study combines high-resolution mesoscale model simulations and comprehensive airborne Doppler radar observations to identify kinematic structures influencing the production and mesoscale distribution of precipitation and microphysical processes during a period of heavy prefrontal orographic rainfall over the Cascade Mountains of Oregon on 13–14 December 2001 during the second phase of the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2) field program. Airborne-based radar detection of precipitation from well upstream of the Cascades to the lee allows a depiction of terrain-induced wave motions in unprecedented detail.

Two distinct scales of mesoscale wave–like air motions are identified: 1) a vertically propagating mountain wave anchored to the Cascade crest associated with strong midlevel zonal (i.e., cross barrier) flow, and 2) smaller-scale (<20-km horizontal wavelength) undulations over the windward foothills triggered by interaction of the low-level along-barrier flow with multiple ridge–valley corrugations oriented perpendicular to the Cascade crest. These undulations modulate cloud liquid water (CLW) and snow mixing ratios in the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5), with modeled structures comparing favorably to radar-documented zones of enhanced reflectivity and CLW measured by the NOAA P3 aircraft.

Errors in the model representation of a low-level shear layer and the vertically propagating mountain waves are analyzed through a variety of sensitivity tests, which indicated that the mountain wave’s amplitude and placement are extremely sensitive to the planetary boundary layer (PBL) parameterization being employed. The effects of 1) using unsmoothed versus smoothed terrain and 2) the removal of upstream coastal terrain on the flow and precipitation over the Cascades are evaluated through a series of sensitivity experiments. Inclusion of unsmoothed terrain resulted in net surface precipitation increases of ∼4%–14% over the windward slopes relative to the smoothed-terrain simulation. Small-scale waves (<20-km horizontal wavelength) over the windward slopes significantly impact the horizontal pattern of precipitation and hence quantitative precipitation forecast (QPF) accuracy.

Corresponding author address: Matthew F. Garvert, Department of Atmospheric Sciences, University of Washington, 408 ATG Building, Box 351640, Seattle, WA 98195-1640. Email: mgarvert@atmos.washington.edu

Abstract

This study combines high-resolution mesoscale model simulations and comprehensive airborne Doppler radar observations to identify kinematic structures influencing the production and mesoscale distribution of precipitation and microphysical processes during a period of heavy prefrontal orographic rainfall over the Cascade Mountains of Oregon on 13–14 December 2001 during the second phase of the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2) field program. Airborne-based radar detection of precipitation from well upstream of the Cascades to the lee allows a depiction of terrain-induced wave motions in unprecedented detail.

Two distinct scales of mesoscale wave–like air motions are identified: 1) a vertically propagating mountain wave anchored to the Cascade crest associated with strong midlevel zonal (i.e., cross barrier) flow, and 2) smaller-scale (<20-km horizontal wavelength) undulations over the windward foothills triggered by interaction of the low-level along-barrier flow with multiple ridge–valley corrugations oriented perpendicular to the Cascade crest. These undulations modulate cloud liquid water (CLW) and snow mixing ratios in the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5), with modeled structures comparing favorably to radar-documented zones of enhanced reflectivity and CLW measured by the NOAA P3 aircraft.

Errors in the model representation of a low-level shear layer and the vertically propagating mountain waves are analyzed through a variety of sensitivity tests, which indicated that the mountain wave’s amplitude and placement are extremely sensitive to the planetary boundary layer (PBL) parameterization being employed. The effects of 1) using unsmoothed versus smoothed terrain and 2) the removal of upstream coastal terrain on the flow and precipitation over the Cascades are evaluated through a series of sensitivity experiments. Inclusion of unsmoothed terrain resulted in net surface precipitation increases of ∼4%–14% over the windward slopes relative to the smoothed-terrain simulation. Small-scale waves (<20-km horizontal wavelength) over the windward slopes significantly impact the horizontal pattern of precipitation and hence quantitative precipitation forecast (QPF) accuracy.

Corresponding author address: Matthew F. Garvert, Department of Atmospheric Sciences, University of Washington, 408 ATG Building, Box 351640, Seattle, WA 98195-1640. Email: mgarvert@atmos.washington.edu

Save
Cover Journal of the Atmospheric Sciences
Journal of the Atmospheric Sciences

  • Benjamin, S. O., and N. L. Seaman, 1985: A simple scheme for objective analysis in curved flow. Mon. Wea. Rev., 113 , 1184–1198.

  • Bousquet, O., and B. F. Smull, 2003a: Airflow and precipitation fields within deep Alpine valleys observed by airborne Doppler radar. J. Appl. Meteor., 42 , 1497–1513.

    • Search Google Scholar
    • Export Citation

  • Bousquet, O., and B. F. Smull, 2003b: Observations and impacts of upstream blocking during a widespread orographic precipitation event. Quart. J. Roy. Meteor. Soc., 129 , 391–409.

    • Search Google Scholar
    • Export Citation

  • Bruintjes, R. T., T. Clark, and W. D. Hall, 1994: Interactions between topopgraphic airflow and cloud/precipitation development during passage of a winter storm in Arizona. J. Atmos. Sci., 51 , 275–285.

    • Search Google Scholar
    • Export Citation

  • Cairns, M. M., and J. Corey, 2003: Mesoscale model simulations of high-wind events in the complex terrain of western Nevada. Wea. Forecasting, 18 , 249–263.

    • Search Google Scholar
    • Export Citation

  • Colle, B., 2004: Sensitivity of orographic precipitation to changing ambient conditions and terrain geometries: An idealized modeling perspective. J. Atmos. Sci., 61 , 588–606.

    • Search Google Scholar
    • Export Citation

  • Colle, B., and C. F. Mass, 1996: An observational and modeling study of the interaction of low-level southwesterly flow with the Olympic Mountains during COAST IOP 4. Mon. Wea. Rev., 124 , 2152–2175.

    • Search Google Scholar
    • Export Citation

  • Colle, B., and C. F. Mass, 2000: The 5–9 February 1996 flooding event over the Pacific Northwest: Sensitivity studies and evaluation of the MM5 precipitation forecasts. Mon. Wea. Rev., 128 , 593–617.

    • Search Google Scholar
    • Export Citation

  • Colle, B., and Y. Zeng, 2004a: Bulk microphysical sensitivities within the MM5 for orographic precipitation. Part I: The Sierra 1986 event. Mon. Wea. Rev., 132 , 2780–2801.

    • Search Google Scholar
    • Export Citation

  • Colle, B., and Y. Zeng, 2004b: Bulk microphysical sensitivities within the MM5 for orographic precipitation. Part II: Impact of barrier width and freezing level. Mon. Wea. Rev., 132 , 2802–2815.

    • Search Google Scholar
    • Export Citation

  • Colle, B., K. Westrick, and C. F. Mass, 1999: Evaluation of MM5 and Eta-10 precipitation forecasts over the Pacific Northwest during the cool season. Wea. Forecasting, 14 , 137–154.

    • Search Google Scholar
    • Export Citation

  • Colle, B., K. Westrick, and C. F. Mass, 2000: MM5 precipitation verification over the Pacific Northwest during, the 1997–99 cool season. Wea. Forecasting, 15 , 730–744.

    • Search Google Scholar
    • Export Citation

  • Colle, B., M. F. Garvert, and J. Wolfe, 2005: Simulations of the 13–14 December 2001 IMPROVE-2 event. Part III: Microphysical budgets and sensitivities. J. Atmos. Sci., 62 , 3535–3558.

    • Search Google Scholar
    • Export Citation

  • Cox, J., J. Steenburgh, D. E. Kingsmill, J. C. Shafer, B. A. Colle, O. Bousquet, B. F. Smull, and H. Cai, 2005: The kinematic structure of a Wasatch mountain winter storm during IPEX IOP3. Mon. Wea. Rev., 133 , 521–542.

    • Search Google Scholar
    • Export Citation

  • Doyle, J. D., and Coauthors, 2000: An intercomparison of model-predicted wave breaking for the 11 January 1972 Boulder windstorm. Mon. Wea. Rev., 128 , 901–914.

    • Search Google Scholar
    • Export Citation

  • Durran, D., 2003: Lee waves and mountain waves. Encyclopedia of Atmospheric Science, Elsevier Science Ltd., 1161–1170.

  • Durran, D., and J. Klemp, 1982: On the effects of moisture on the Brunt–Väisälä frequency. J. Atmos. Sci., 39 , 2152–2158.

  • Einaudi, F., and D. Lalas, 1973: The propagation of acoustic gravity waves in a moist atmosphere. J. Atmos. Sci., 30 , 365–376.

  • Frush, C. L., P. H. Hildebrand, and C. Walther, 1986: The NCAR airborne Doppler radar. Part II: System design considerations. Preprints, 23d Conf. on Radar Meteorology, Snowmass, CO, Amer. Meteor. Soc., 151–154.

  • Garvert, M. F., B. Colle, and C. Mass, 2005a: The 13–14 December 2001 IMPROVE-2 event. Part I: Synoptic and mesoscale evolution and comparison with a mesoscale model simulation. J. Atmos. Sci., 62 , 3474–3492.

    • Search Google Scholar
    • Export Citation

  • Garvert, M. F., C. Woods, B. Colle, C. Mass, and P. Hobbs, 2005b: The 13–14 December 2001 IMPROVE-2 event. Part II: Evaluation of cloud and precipitation structures in the MM5 model simulation. J. Atmos. Sci., 62 , 3520–3534.

    • Search Google Scholar
    • Export Citation

  • Grell, G. A., 1993: Prognostic evaluation of assumptions used by cumulus parameterizations. Mon. Wea. Rev., 121 , 764–787.

  • Hildebrand, P. H., 1998: Shear-parallel moist convection over the tropical ocean: A case study from 18 February 1993 TOGA COARE. Mon. Wea. Rev., 126 , 1952–1976.

    • Search Google Scholar
    • Export Citation

  • Hong, S-Y., and H-L. Pan, 1996: Nonlocal boundary layer vertical diffusion in a medium-range forecast model. Mon. Wea. Rev., 124 , 2322–2339.

    • Search Google Scholar
    • Export Citation

  • Houze, R., and S. Medina, 2005: Turbulence as a mechanism for orographic precipitation enhancement. J. Atmos. Sci., 62 , 3599–3623.

  • Janjic, Z. I., 1990: The step-mountain coordinate: Physical package. Mon. Wea. Rev., 118 , 1429–1443.

  • Janjic, Z. I., 1994: The step-mountain Eta coordinate model: Further developments of the convection, viscous sublayer, and turbulence closure schemes. Mon. Wea. Rev., 122 , 927–945.

    • Search Google Scholar
    • Export Citation

  • Jorgensen, D. P., and B. F. Smull, 1993: Mesovortex circulations seen by airborne Doppler radar within a bow-echo mesoscale convective system. Bull. Amer. Meteor. Soc., 74 , 2146–2157.

    • Search Google Scholar
    • Export Citation

  • Leise, J., 1982: A multi-dimensional, scale-telescoped filter and data extension package. NOAA Tech. Memo. ERL WPL-82, 20 pp. [Available from NOAA/ETL, 325 Broadway, Boulder, CO 80303.].

  • Marwitz, J. D., 1987a: Deep orographic storms over the Sierra Nevada. Part I: Thermodynamic and kinematic structure. J. Atmos. Sci., 44 , 159–173.

    • Search Google Scholar
    • Export Citation

  • Marwitz, J. D., 1987b: Deep orographic storms over the Sierra Nevada. Part II: The precipitation processes. J. Atmos. Sci., 44 , 174–185.

    • Search Google Scholar
    • Export Citation

  • Medina, S., and R. Houze, 2003: Air motions and precipitation growth in alpine storms. Quart. J. Roy. Meteor. Soc., 129 , 345–371.

  • Medina, S., B. Smull, R. Houze, and M. Steiner, 2005: Cross-barrier flow during orographic precipitation events: Results from MAP and IMPROVE. J. Atmos. Sci., 62 , 3580–3598.

    • Search Google Scholar
    • Export Citation

  • Noh, Y., W. G. Cheon, S. Y. Hong, and S. Raasch, 2003: Improvement of the K-profile model for the planetary boundary layer based on large eddy simulation data. Bound.-Layer Meteor., 107 , 401–427.

    • Search Google Scholar
    • Export Citation

  • Peng, M. S., and W. T. Thompson, 2003: Some aspects of the effect of surface friction on flows over mountains. Quart. J. Roy. Meteor. Soc., 129 , 2527–2557.

    • Search Google Scholar
    • Export Citation

  • Rauber, R., 1992: Microphysical structure and evolution of a central Sierra Nevada orographic cloud system. J. Appl. Meteor., 31 , 3–24.

    • Search Google Scholar
    • Export Citation

  • Ray, P., C. Ziegler, W. Bumgarner, and R. Serafin, 1980: Single and multiple Doppler radar observations of tornadic storms. Mon. Wea. Rev., 108 , 1607–1625.

    • Search Google Scholar
    • Export Citation

  • Rotunno, R., and R. Ferretti, 2001: Mechanisms of intense Alpine rainfall. J. Atmos. Sci., 58 , 1732–1749.

  • Smith, R. B., 1979: The influence of mountains on the atmosphere. Advances in Geophysics, Vol. 21, Academic Press, 135–137.

  • Smith, R. B., 1980: Linear theory of stratified hydrostatic flow past an isolated mountain. Tellus, 32 , 348–364.

  • Smith, R. B., 1989: Hydrostatic airflow over mountains. Advances in Geophysics, Vol. 31, Academic Press, 1–41.

  • Smith, R. B., I. Barstad, and L. Bonneau, 2005: Orographic precipitation and Oregon’s climate transition. J. Atmos. Sci., 62 , 177–191.

    • Search Google Scholar
    • Export Citation

  • Stauffer, D. R., and N. L. Seaman, 1990: Use of four-dimensional data assimilation in a limited-area mesoscale model. Part I: Experiments with synoptic scale data. Mon. Wea. Rev., 118 , 1250–1277.

    • Search Google Scholar
    • Export Citation

  • Stauffer, D. R., N. L. Seaman, and F. S. Binkowski, 1991: Use of four-dimensional data assimilation in a limited-area mesoscale model. Part II: Effects of data assimilation within the planetary bounday layer. Mon. Wea. Rev., 119 , 734–754.

    • Search Google Scholar
    • Export Citation

  • Steenburgh, J., and C. Mass, 1996: Interaction of an intense extratropical cyclone with coastal orography. Mon. Wea. Rev., 124 , 1329–1352.

    • Search Google Scholar
    • Export Citation

  • Stoelinga, M., and Coauthors, 2003: Improvement of microphysical parameterizations through observational verification experiments IMPROVE. Bull. Amer. Meteor. Soc., 84 , 1807–1826.

    • Search Google Scholar
    • Export Citation

  • Thompson, G., R. M. Rasmussen, and K. Manning, 2004: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part I: Description and sensitivity analysis. Mon. Wea. Rev., 132 , 519–542.

    • Search Google Scholar
    • Export Citation

  • Woods, C., M. T. Stoelinga, J. D. Locatelli, and P. V. Hobbs, 2005: Cloud structures and microphysical processes during the 13 December 2001 IMPROVE-2 event. J. Atmos. Sci., 62 , 3493–3519.

    • Search Google Scholar
    • Export Citation

  • Yu, C. K., and B. F. Smull, 2000: Airborne observations of a landfalling cold front upstream of steep coastal orography. Mon. Wea. Rev., 128 , 1577–1603.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 1260 560 256
PDF Downloads 633 124 10