Editorial Type:
Article
Article Type:
Research Article

Synoptic-Scale and Mesoscale Environments Conducive to Forest Fires during the October 2003 Extreme Fire Event in Southern California

Chenjie Huang NOAA/NWS/NCEP/Climate Prediction Center, Camp Springs, Maryland, and Wyle Information Systems, McLean, Virginia

Search for other papers by Chenjie Huang in
Current site
Google Scholar
PubMed Close
,
Y-L. Lin Department of Physics, North Carolina Agricultural and Technical State University, Greensboro, North Carolina

Search for other papers by Y-L. Lin in
Current site
Google Scholar
PubMed Close
,
M. L. Kaplan Division of Atmospheric Sciences, Desert Research Institute, Reno, Nevada

Search for other papers by M. L. Kaplan in
Current site
Google Scholar
PubMed Close
, and
J. J. Charney North Central Research Station, USDA Forest Service, East Lansing, Michigan

Search for other papers by J. J. Charney in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Mar 2009
DOI:
https://doi.org/10.1175/2008JAMC1818.1
Page(s):
553–579
Restricted access

Abstract

This study has employed both observational data and numerical simulation results to diagnose the synoptic-scale and mesoscale environments conducive to forest fires during the October 2003 extreme fire event in southern California. A three-stage process is proposed to illustrate the coupling of the synoptic-scale forcing that is evident from the observations, specifically the high pressure ridge and the upper-level jet streak, which leads to meso-α-scale subsidence in its exit region, and the mesoscale forcing that is simulated by the numerical model, specifically the wave breaking and turbulence as well as the wave-induced critical level, which leads to severe downslope (Santa Ana) winds. Two surges of dry air were found to reach the surface in southern California as revealed in the numerical simulation. The first dry air surge arrived as a result of moisture divergence and isallobaric adjustments behind a surface cold front. The second dry air surge reached southern California as the meso-α- to meso-β-scale subsidence and the wave-induced critical level over the coastal ranges phased to transport the dry air from the upper-level jet streak exit region toward the surface and mix the dry air down to the planetary boundary layer on the lee side of the coastal ranges in southern California. The wave-breaking region on the lee side acted as an internal boundary to reflect the mountain wave energy back to the ground and created severe downslope winds through partial resonance with the upward-propagating mountain waves.

Corresponding author address: Ms. Chenjie Huang, NOAA/CPC and Wyle Information Systems, 1651 Old Meadow Rd., McLean, VA 22102. Email: chenjie.huang@noaa.gov

Abstract

This study has employed both observational data and numerical simulation results to diagnose the synoptic-scale and mesoscale environments conducive to forest fires during the October 2003 extreme fire event in southern California. A three-stage process is proposed to illustrate the coupling of the synoptic-scale forcing that is evident from the observations, specifically the high pressure ridge and the upper-level jet streak, which leads to meso-α-scale subsidence in its exit region, and the mesoscale forcing that is simulated by the numerical model, specifically the wave breaking and turbulence as well as the wave-induced critical level, which leads to severe downslope (Santa Ana) winds. Two surges of dry air were found to reach the surface in southern California as revealed in the numerical simulation. The first dry air surge arrived as a result of moisture divergence and isallobaric adjustments behind a surface cold front. The second dry air surge reached southern California as the meso-α- to meso-β-scale subsidence and the wave-induced critical level over the coastal ranges phased to transport the dry air from the upper-level jet streak exit region toward the surface and mix the dry air down to the planetary boundary layer on the lee side of the coastal ranges in southern California. The wave-breaking region on the lee side acted as an internal boundary to reflect the mountain wave energy back to the ground and created severe downslope winds through partial resonance with the upward-propagating mountain waves.

Corresponding author address: Ms. Chenjie Huang, NOAA/CPC and Wyle Information Systems, 1651 Old Meadow Rd., McLean, VA 22102. Email: chenjie.huang@noaa.gov

Save
Cover Journal of Applied Meteorology and Climatology
Journal of Applied Meteorology and Climatology

  • Brotak, E. A., and W. E. Reifsnyder, 1977a: An investigation of the synoptic situations associate with major wildland fires. J. Appl. Meteor., 16 , 867–870.

    • Search Google Scholar
    • Export Citation

  • Brotak, E. A., and W. E. Reifsnyder, 1977b: Predicting major wildland fire occurrence. Fire Management Notes, 38 (3) 5–8.

  • Byram, G. M., 1954: Atmospheric conditions related to blow-up fires. Southeastern Forest Experiment Station Paper 35, USDA Forest Service, Asheville, NC, 42 pp.

    • Search Google Scholar
    • Export Citation

  • Clark, T. L., and W. R. Peltier, 1984: Critical level reflection and the resonant growth of nonlinear mountain waves. J. Atmos. Sci., 41 , 3122–3134.

    • Search Google Scholar
    • Export Citation

  • Durran, D. R., 1990: Mountain waves and downslope winds. Atmospheric Processes over Complex Terrain, Meteor. Monogr., No. 45, Amer. Meteor. Soc., 59–81.

    • Search Google Scholar
    • Export Citation

  • Eliassen, A., and E. Palm, 1960: On the transfer of energy in stationary mountain waves. Geofys. Publ., 22 , 1–23.

  • Glickman, T., Ed. 2000: Glossary of Meteorology. 2nd ed. Amer. Meteor. Soc., 855 pp.

  • Holton, J. R., 2004: An Introduction to Dynamic Meteorology. 4th ed. Elsvier, 535 pp.

  • Johnson, D. L., 2004: Southern California wildfires October 20 to November 3, 2003. NOAA/NWS Service Assessment, Silver Spring, MD, 45 pp.

    • Search Google Scholar
    • Export Citation

  • Kaplan, M. L., Y-L. Lin, J. J. Charney, K. D. Pfeiffer, D. B. Ensley, R. P. Weglarz, and D. S. DeCroix, 2000: A terminal area PBL prediction system at Dallas-Fort Worth and its application in simulating diurnal PBL jets. Bull. Amer. Meteor. Soc., 81 , 2179–2204.

    • Search Google Scholar
    • Export Citation

  • Klemp, J. B., and D. K. Lilly, 1975: The dynamics of induced Downslope winds. J. Atmos. Sci., 32 , 320–339.

  • Kondo, J., and T. Kuwagata, 1992: Enhancement of forest fires over northeastern Japan due to atypical strong dry wind. J. Appl. Meteor., 31 , 386–396.

    • Search Google Scholar
    • Export Citation

  • Lin, Y-L., 2007: Mesoscale Dynamics. Cambridge University Press, 630 pp.

  • MESO, Inc., 1994: MASS version 5.6 reference manual. MESO Inc., Troy, NY, 118 pp. [Available from MESO Inc., 185 Jordan Rd., Troy, NY 12180.].

    • Search Google Scholar
    • Export Citation

  • Raphael, M. N., 2003: The Santa Ana winds of California. Earth Interactions, 7 .[Available online at http://EarthInteractions.org.].

  • Schaefer, V. J., 1957: The relationship of jet streams to forest wildfires. J. For., 119 , 419–425.

  • Small, I. J., 1995: Santa Ana winds and the fire outbreak of fall 1993. NOAA Tech. Memo. NWS WR-230, 15 pp.

  • Small, R. T., 1957: The relationship of weather factors to the rate of spread of the Robie Creek fire. Mon. Wea. Rev., 85 , 1–8.

  • Smith, R. B., 1985: On severe downslope winds. J. Atmos. Sci., 42 , 2597–2603.

  • Uccellini, L. W., and D. R. Johnson, 1979: The coupling of upper- and lower-tropospheric jet streaks and implications for the development of severe convective storms. Mon. Wea. Rev., 107 , 682–703.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 2252 1692 535
PDF Downloads 391 70 8