• Abaurrea, J., and J. Asín, 2005: Forecasting local daily precipitation patterns in a climate change scenario. Climate Res., 28, 183197.

    • Search Google Scholar
    • Export Citation
  • Alley, R. B., and Coauthors, 2007: Summary for policymakers. Climate Change 2007: The Physical Science Basis, S. Solomon et al., Eds., Cambridge University Press, 1–18.

    • Search Google Scholar
    • Export Citation
  • Buishand, T. A., M. V. Shabalova, and T. Brandsma, 2004: On the choice of the temporal aggregation level for statistical downscaling of precipitation. J. Climate, 17, 18161827.

    • Search Google Scholar
    • Export Citation
  • Cheng, S. C., G. Li, Q. Li, and H. Auld, 2008: Statistical downscaling of hourly and daily climate scenarios for various meteorological variables in south-central Canada. Theor. Appl. Climatol., 91, 129147, doi:10.1007/s00704-007-0302-8.

    • Search Google Scholar
    • Export Citation
  • Cheng, S. C., G. Li, Q. Li, and H. Auld, 2010: A synoptic weather typing approach to simulate daily rainfall and extremes in Ontario, Canada: Potential for climate change projections. J. Appl. Meteor. Climatol., 49, 845866.

    • Search Google Scholar
    • Export Citation
  • Cubasch, U., J. Waszkewitz, G. Hegerl, and J. Perlwitz, 1995: Regional climate changes as simulated time-slice experiments. Climatic Change, 31, 273304.

    • Search Google Scholar
    • Export Citation
  • Emori, S., and S. J. Brown, 2005: Dynamic and thermodynamic changes in mean and extreme precipitation under changed climate. Geophys. Res. Lett., 32, L17706, doi:10.1029/2005GL023272.

    • Search Google Scholar
    • Export Citation
  • Environment Canada, cited 2006: Data. [Available online at http://www.cccma.bc.ec.gc.ca/data/data.shtml.]

  • Fealy, R., and J. Sweeney, 2007: Statistical downscaling of precipitation for a selection of sites in Ireland employing a generalised linear modelling approach. Int. J. Climatol., 27, 20832094.

    • Search Google Scholar
    • Export Citation
  • Fowler, H. J., S. Blenkinsop, and C. Tebaldi, 2007: Linking climate change modeling to impacts studies: Recent advances in downscaling techniques for hydrological modeling. Int. J. Climatol., 27, 15471578.

    • Search Google Scholar
    • Export Citation
  • Galway, J. G., 1956: The lifted index as a predictor of latent instability. Bull. Amer. Meteor. Soc., 37, 528529.

  • George, J. J., 1960: Weather Forecasting for Aeronautics. Academic Press, 673 pp.

  • Goodess, C. M., and J. P. Palutikof, 1998: Development of daily rainfall scenarios for southeast Spain using a circulation-type approach to downscaling. Int. J. Climatol., 18, 10511083.

    • Search Google Scholar
    • Export Citation
  • Haylock, M. R., G. C. Cawley, C. Harpham, R. L. Wilby, and C. M. Goodess, 2006: Downscaling heavy precipitation over the United Kingdom: A comparison of dynamical and statistical methods and their future scenarios. Int. J. Climatol., 26, 13971415.

    • Search Google Scholar
    • Export Citation
  • Kalkstein, L. S., 1979: A synoptic climatological approach for environmental analysis. Proc. Middle States Div. Assoc. Amer. Geogr., 13, 6875.

    • Search Google Scholar
    • Export Citation
  • Katz, R. W., 2002: Techniques for estimating uncertainty in climate change scenarios and impact studies. Climate Res., 20, 167185.

  • Kharin, V. V., and F. W. Zwiers, 2005: Estimating extremes in transient climate change simulations. J. Climate, 18, 11561173.

  • Klecka, W. R., 1980: Discriminant Analysis. Sage University Press, 71 pp.

  • Kostopoulou, E., and P. D. Jones, 2007a: Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: Map-pattern classification. Int. J. Climatol., 27, 11891214.

    • Search Google Scholar
    • Export Citation
  • Kostopoulou, E., and P. D. Jones, 2007b: Comprehensive analysis of the climate variability in the eastern Mediterranean. Part II: Relationships between atmospheric circulation patterns and surface climatic elements. Int. J. Climatol., 27, 13511371.

    • Search Google Scholar
    • Export Citation
  • Lam, K. C., and C. S. Cheng, 1998: A synoptic climatological approach to forecast concentrations of sulfur dioxide and nitrogen oxides in Hong Kong. Environ. Pollut., 101, 183191.

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., C. Covey, T. Delworth, M. Latif, B. McAvaney, J. F. B. Mitchell, R. J. Stouffer, and K. E. Taylor, 2007: The WCRP CMIP3 multimodel dataset: A new era in climate change research. Bull. Amer. Meteor. Soc., 88, 13831394.

    • Search Google Scholar
    • Export Citation
  • Miller, R. C., 1972: Notes on analysis and severe storm forecasting procedures of the Air Force Global Weather Central. U.S. Air Force Air Weather Service Tech. Rep. 200(R), 190 pp.

    • Search Google Scholar
    • Export Citation
  • Nguyen, V. T. V., T. D. Nguyen, and P. Gachon, 2006: On the linkage of large-scale climate variability with local characteristics of daily precipitation and temperature extremes: An evaluation of statistical downscaling methods. Advances in Geosciences, Vol. 4, Academic Press, 1–9.

    • Search Google Scholar
    • Export Citation
  • Perry, A., 1983: Growth points in synoptic climatology. Prog. Phys. Geogr., 7, 9096.

  • Program for Climate Model Diagnosis and Intercomparison, cited 2006: WCRP CMIP3 multi-model dataset. [Available online at http://www-pcmdi.llnl.gov/ipcc/about_ipcc.php.]

    • Search Google Scholar
    • Export Citation
  • Tebaldi, C., K. Hayhoe, J. M. Arblaster, and G. A. Meehl, 2006: Going to the extremes: An intercomparison of model-simulated historical and future changes in extreme events. Climatic Change, 79, 185211.

    • Search Google Scholar
    • Export Citation
  • Wilby, R. L., and T. M. L. Wigley, 1997: Downscaling general circulation model output: A review of methods and limitations. Prog. Phys. Geogr., 21, 530548.

    • Search Google Scholar
    • Export Citation
  • Wilby, R. L., C. W. Dawson, and E. M. Barrow, 2002: SDSM — A decision support tool for the assessment of regional climate change impacts. Environ. Model. Software, 17, 147159.

    • Search Google Scholar
    • Export Citation
  • Zwiers, F. W., and V. V. Kharin, 1998: Changes in the extremes of the climate simulated by CCC GCM2 under CO2 doubling. J. Climate, 11, 22002222.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 252 89 10
PDF Downloads 112 31 3

A Synoptic Weather-Typing Approach to Project Future Daily Rainfall and Extremes at Local Scale in Ontario, Canada

View More View Less
  • 1 Atmospheric Science and Applications Unit, Meteorological Service of Canada Branch, Environment Canada, Toronto, Ontario, Canada
  • | 2 Adaptation and Impacts Research Section, Atmospheric Science and Technology Directorate, Science and Technology Branch, Environment Canada, Toronto, Ontario, Canada
Restricted access

Abstract

This paper attempts to project possible changes in the frequency of daily rainfall events late in this century for four selected river basins (i.e., Grand, Humber, Rideau, and Upper Thames) in Ontario, Canada. To achieve this goal, automated synoptic weather typing as well as cumulative logit and nonlinear regression methods was employed to develop within-weather-type daily rainfall simulation models. In addition, regression-based downscaling was applied to downscale four general circulation model (GCM) simulations to three meteorological stations (i.e., London, Ottawa, and Toronto) within the river basins for all meteorological variables (except rainfall) used in the study. Using downscaled GCM hourly climate data, discriminant function analysis was employed to allocate each future day for two windows of time (2046–65, 2081–2100) into one of the weather types. Future daily rainfall and its extremes were projected by applying within-weather-type rainfall simulation models together with downscaled future GCM climate data. A verification process of model results has been built into the whole exercise (i.e., statistical downscaling, synoptic weather typing, and daily rainfall simulation modeling) to ascertain whether the methods are stable for projection of changes in frequency of future daily rainfall events.

Two independent approaches were used to project changes in frequency of daily rainfall events: method I—comparing future and historical frequencies of rainfall-related weather types, and method II—applying daily rainfall simulation models with downscaled future climate information. The increases of future daily rainfall event frequencies and seasonal rainfall totals (April–November) projected by method II are usually greater than those derived by method I. The increase in frequency of future daily heavy rainfall events greater than or equal to 25 mm, derived from both methods, is likely to be greater than that of future daily rainfall events greater than or equal to 0.2 mm: 35%–50% versus 10%–25% over the period 2081–2100 derived from method II. In addition, the return values of annual maximum 3-day accumulated rainfall totals are projected to increase by 20%–50%, 30%–55%, and 25%–60% for the periods 2001–50, 2026–75, and 2051–2100, respectively. Inter-GCM and interscenario uncertainties of future rainfall projections were quantitatively assessed. The intermodel uncertainties are similar to the interscenario uncertainties, for both method I and method II. However, the uncertainties are generally much smaller than the projection of percentage increases in the frequency of future seasonal rain days and future seasonal rainfall totals. The overall mean projected percentage increases are about 2.6 times greater than overall mean intermodel and interscenario uncertainties from method I; the corresponding projected increases from method II are 2.2–3.7 times greater than overall mean uncertainties.

Corresponding author address: Dr. Chad Shouquan Cheng, Atmospheric Science and Applications Unit, Meteorological Service of Canada Branch, Environment Canada, 4905 Dufferin St., Toronto ON M3H 5T4, Canada. E-mail: shouquan.cheng@ec.gc.ca

Abstract

This paper attempts to project possible changes in the frequency of daily rainfall events late in this century for four selected river basins (i.e., Grand, Humber, Rideau, and Upper Thames) in Ontario, Canada. To achieve this goal, automated synoptic weather typing as well as cumulative logit and nonlinear regression methods was employed to develop within-weather-type daily rainfall simulation models. In addition, regression-based downscaling was applied to downscale four general circulation model (GCM) simulations to three meteorological stations (i.e., London, Ottawa, and Toronto) within the river basins for all meteorological variables (except rainfall) used in the study. Using downscaled GCM hourly climate data, discriminant function analysis was employed to allocate each future day for two windows of time (2046–65, 2081–2100) into one of the weather types. Future daily rainfall and its extremes were projected by applying within-weather-type rainfall simulation models together with downscaled future GCM climate data. A verification process of model results has been built into the whole exercise (i.e., statistical downscaling, synoptic weather typing, and daily rainfall simulation modeling) to ascertain whether the methods are stable for projection of changes in frequency of future daily rainfall events.

Two independent approaches were used to project changes in frequency of daily rainfall events: method I—comparing future and historical frequencies of rainfall-related weather types, and method II—applying daily rainfall simulation models with downscaled future climate information. The increases of future daily rainfall event frequencies and seasonal rainfall totals (April–November) projected by method II are usually greater than those derived by method I. The increase in frequency of future daily heavy rainfall events greater than or equal to 25 mm, derived from both methods, is likely to be greater than that of future daily rainfall events greater than or equal to 0.2 mm: 35%–50% versus 10%–25% over the period 2081–2100 derived from method II. In addition, the return values of annual maximum 3-day accumulated rainfall totals are projected to increase by 20%–50%, 30%–55%, and 25%–60% for the periods 2001–50, 2026–75, and 2051–2100, respectively. Inter-GCM and interscenario uncertainties of future rainfall projections were quantitatively assessed. The intermodel uncertainties are similar to the interscenario uncertainties, for both method I and method II. However, the uncertainties are generally much smaller than the projection of percentage increases in the frequency of future seasonal rain days and future seasonal rainfall totals. The overall mean projected percentage increases are about 2.6 times greater than overall mean intermodel and interscenario uncertainties from method I; the corresponding projected increases from method II are 2.2–3.7 times greater than overall mean uncertainties.

Corresponding author address: Dr. Chad Shouquan Cheng, Atmospheric Science and Applications Unit, Meteorological Service of Canada Branch, Environment Canada, 4905 Dufferin St., Toronto ON M3H 5T4, Canada. E-mail: shouquan.cheng@ec.gc.ca
Save