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Boundary-Layer Meteorology

, Volume 64, Issue 1–2, pp 15–54 | Cite as

Mesoscale observations of surface fronts and low pressure centres in Canadian East Coast winter storms

  • Peter A. Taylor
  • James R. Salmon
  • Ronald E. Stewart
Article

Abstract

The movements of surface cold and warm fronts and low pressure centres have been observed in several Atlantic Canada winter storms. Statistical aspects of the ‘well-defined’ surface fronts (7 warm and 6 cold) are presented. Surface wind direction change was considered as the best indicator of the boundaries of the front; frontal zone widths ranged from 23 to 144 km. Average values of wind shifts were 107° for the cold fronts and 85° for warm fronts. Several case studies are presented, based primarily on surface MesoNet data (near Halifax, Nova Scotia and on Sable Island). In two of the cold fronts, there was a two-stage surface structure and rapid evolution as the front passed over the MesoNet. In some cases, both warm and cold, the wind shift and temperature change were coincident while in others they were not. In particular we observed that wind shifts often started 20–30 min ahead of the start of a temperature decrease in these cold frontal passages. A possible mechanism for this is discussed. We found little or no evidence of along-front structure in our data although other investigators have found considerable along-front variation on scales of 0(10 km). Observations of the passage of one low pressure centre are presented. In a second case, surface temperature changes indicated an apparent low pressure centre passage through the Sable Island MesoNet but closer inspection provides an alternative interpretation.

Keywords

Nova Scotia Surface Front Cold Front Frontal Zone Zone Width 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Anderson, C.: 1990, ‘Estimating the Propagation Velocity of Atmospheric Fronts from Surface Wind Observations’,Atmos.-Ocean 28, 330–344.Google Scholar
  2. Barry, R. G. and Chorley, R. J.: 1987,Atmosphere, Weather and Climate, 5th Edition, Methuen and Co., London, 460 pp.Google Scholar
  3. Bjerknes, J.: 1919, ‘On the Structure of Moving Cyclones’,Geofysiske Publicationer 1, 3–8.Google Scholar
  4. Bjerknes, J. and Solberg, H.: 1992, ‘Life Cycles of Cyclones and Polar Front Theory of Atmospheric Circulation’,Geofysiske Publikationer 3, 3–18Google Scholar
  5. Browning, K. A.: 1985, ‘Conceptual Models of Precipitation Systems’,ESA Journal,9, 157–180.Google Scholar
  6. Browning, K. A. and Monk, G. A.: 1982, ‘A Simple Model for the Synoptic Analysis of Cold Fronts’,Quart. J. Roy. Meteorol. Soc. 108, 435–452.Google Scholar
  7. Carbone, R. E.: 1982, ‘A Severe Frontal Rain Band. Part I: Stormwide Hydrodynamic Structure’,J. Atmos. Sci. 39, 258–279.Google Scholar
  8. Carlson, T. N.: 1980, ‘Airflow Through Midlatitude Cyclones and the Comma Cloud Pattern’,Mon. Wea. Rev. 108, 1498–1509.Google Scholar
  9. Donaldson, N. R. and Stewart, R. E.: 1989, ‘On the Precipitation Regions Within Two Winter Storms Affecting Atlantic Canada’,Atmos.-Ocean 27, 108–129.Google Scholar
  10. Donaldson, N. R. and Stewart, R. E.: 1992, ‘Fog induced by mixed-phase precipitation’,Atmospheric Research, in press.Google Scholar
  11. Erikson, W.: 1971, ‘Uber die Haufigkeit meteorologischer Fronten uber Europa und ihre Bedeutung fur die klimatische Gleiderung des Kontinents’,Erd kunde 25, 163–178.Google Scholar
  12. Fraedrich, K., Bach, R. and Naujokat, G.: 1986, ‘A Single Station Climatology of Central European Fronts: Number, time and Precipitation Statistics’,Contributions to Atmos. Phys. 59, 54–65.Google Scholar
  13. Hobbs, P. V. and Persson, P. O. G.: 1982, ‘The Mesoscale and Microscale Structure and Organisation of Clouds and Precipitation in Mid-Latitude Cyclones. Part V: The Substructure of Narrow Cold-Frontal Rainbands’,J. Atmos. Sci. 39, 280–295.Google Scholar
  14. Hoinka, K. P. 1985, ‘On fronts in Central Europe’,Contributions to Atmos. Phys. 58, 560–571.Google Scholar
  15. Hoskins, B. J. and Bretherton, F. P.: 1972, ‘Atmospheric Frontogenesis Models: Mathematical Formulation and Solution’,J. Atmos. Sci. 29, 11–37.Google Scholar
  16. Keyser, D.: 1986, ‘Atmospheric Fronts: An Observational Perspective’, In P. S. Ray (Ed.),Mesoscale Meteorology and Forecasting, Amer. Met. Soc., Boston, pp. 216–258.Google Scholar
  17. Martin, H. C.: 1973, ‘Some Observations of the Microstructure of Dry Cold Fronts’,J. Appl. Meterol. 12, 658–663.Google Scholar
  18. Martin, J. E., Locatelli, J. D. and Hobbs, P. V.: 1990, ‘Organization and Structure of Clouds and Precipitation on the Mid-Atlantic Coast of the United States. Part III: The Evolution of a Middle-Tropospheric Cold Front’,Mon. Wea. Rev. 118, 195–217.Google Scholar
  19. McBean, G. A. and Stewart, R. E.: 1991, ‘Structure of a Frontal System over the Northeast Pacific Ocean’,Mon. Wea. Rev. 119, 997–1013.Google Scholar
  20. McIntosh, D. H. and Thom, A. S.: 1973,Essentials of Meteorology, Wykeham, London, 238 pp.Google Scholar
  21. Palmen, E. and Newton, C. W.: 1969,Atmospheric Circulation Systems, Academic Press, Orlando, 603 pp.Google Scholar
  22. Pedgley, D. E.: 1962,A Course in Elementary Meteorology, HMSO, London, 189 pp.Google Scholar
  23. Salmon, J. and Taylor, P. A.: 1989, ‘CASP 1986; Halifax and Sable Island MesoNets’,Data Report. AES, Downsview.Google Scholar
  24. Sanders, F.: 1955, ‘An Investigation of the Structure and Dynamics of an Intense Surface Frontal Zone’,J. Meteorol. 12, 542–552.Google Scholar
  25. Sanders, F.: 1983, ‘Observations of Fronts’, in D. K. Lilly and T. Gal-Chen (Eds.),Mesoscale Meteorology — Theories, Observations and Models, D. Reidel, Dordrecht, pp. 175–303.Google Scholar
  26. Shapiro, M. A.: 1984, ‘Meteorological Tower Measurements at a Surface Cold Front’,Mon. Wea. Rev. 112, 1634–1639.Google Scholar
  27. Shapiro, M. A., Donall, E. G., Neiman, P. J., Fedor, L. S. and Gonzalez, N.: 1991, ‘Recent Refinements in the Conceptual Models of Extratropical Cyclones’,Proc 1st International Symposium on Winter Storms, AMS, New Orlenas, pp. 6–14.Google Scholar
  28. Sheppard, P. A.: 1956, ‘Airflow over Mountains’,Quart. J. R. Meteorol Soc. 82, 528–529.Google Scholar
  29. Smith, R. B.: 1989, ‘Hydrostatic Flow over Mountains’,Adv. Geophys. 31, 1–42.Google Scholar
  30. Smith, R. B.: 1990, ‘Why Can't Stably Stratified Air Rise over High Ground?’, in W. Blumen (Ed.),Atmospheric Processes over Complex Terrain, Am. Meteorol. Soc. Meteorological Monograph, Vol. 23, Number 45, pp. 105–107.Google Scholar
  31. Smith, R. K. and Reeder, M. J.: 1988, ‘On the Movement and Low-Level Structure of Cold Fronts’,Mon. Wea. Rev. 116, 1927–1944.Google Scholar
  32. Snyder, W. H., Thompson, R. S., Eskridge, R. E., Lawson, R. I., Castro, I. P., Lee, J. I., Hunt, J. C. R. and Ogawa, Y.: 1985, ‘The Structure of Strongly Stratified Flow over Hills; Dividing Streamline Concept’,J. Fluid Mech. 152, 249–288.Google Scholar
  33. Stewart, R. E. and Macpherson, S. R.: 1989, ‘Winter Storm Structure and Melting-Induced Circulations’,Atmos.-Ocean 27, 5–23.Google Scholar
  34. Stewart, R. E., Shaw, R. W. and Isaac, G. A.: 1987, ‘Canadian Atlantic Storms Program: the Meteorological Field Project’,Bull. Amer. Meteorol. Soc. 68, 338–345.Google Scholar
  35. Strapp, J. W., Power, J. A. and Macdonald, K. A.: 1988, ‘CASP field summary’,Atmos. Envir. Service Report. AES Downsview, Canada.Google Scholar

Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • Peter A. Taylor
    • 1
  • James R. Salmon
    • 2
  • Ronald E. Stewart
    • 3
    • 1
  1. 1.York UniversityNorth YorkCanada
  2. 2.CMOS Accredited ConsultantBurlingtonCanada
  3. 3.Atmospheric Environment ServiceDownsviewCanada

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