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Understanding Droughts in Canada: Insights and Projections

Explore the occurrence, impacts, and research needs of droughts in Canada, covering historical trends, monitoring techniques, and future predictions. Discover how climate patterns affect drought severity and what research is essential for better preparation.

frankmorrison
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Understanding Droughts in Canada: Insights and Projections

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  1. Droughts in Canada: An Overview Barrie Bonsal Environment Canada Saskatoon, SK, Canada

  2. Outline • Background • Past drought occurrence • Large-scale atmospheric causes • Current monitoring & prediction • Future droughts • Research requirements

  3. Droughts in Canada

  4. Drought Impacts Agriculture

  5. Drought Impacts Water Resources

  6. Drought Impacts

  7. Drought Research in Canada • Fragmented – spatially and temporally • Based on severe drought occurrence (e.g., 1999-2005) • Majority for Canadian Prairies • Historical comparisons difficult due to short and variable climate station records • Canadian droughts unique – both cold and warm season phenomenon

  8. Drought Occurrence Annual PDSI

  9. Summer (JJA) Drought Change 1925 - 1990 Mean Summer Temperature Summer Precipitation

  10. Drought Occurrence – Southern Prairies (1915-2002) SPI PDSI

  11. R e c o n s t r u c t e d R e g i o n a l J u l y 2 0 -2 1700 1800 1900 2000 2 0 -2 1600 1700 1800 1900 2000 Palmer Drought Severity Index (Sauchyn et al. 2001) SouthwesternSaskatchewan frequentdrought decadaldrought North-centralMontana

  12. Warm, Dry Winters Over Canada 500mb Flow 500mb Anomalies • El Niño, +PNA, +PDO, Deep Aleutian Low

  13. Hot, Dry Summers Over Western Canada 500mb Flow 500mb Anomalies • +PNA, Meridional Flow, +PDO?

  14. Coupled SVD pattern between Global Winter SSTs and Summer PDSI (1940-2002) Winter Interannual and interdecadal ENSO-like pattern is associated with dry summer conditions in western and central Canada. Squared Covariance Fraction = 28%, Correlation between time expansion = 0.5 (Shabbar and Skinner, 2004)

  15. Circulation Differences Sep-Aug 1988 Sep-Aug 1961 Sep-Aug 2001 Sep-Aug 2002

  16. Drought Monitoring • Real-time information on drought conditions over agricultural regions of Canada • National map illustrating current and historical temperature, precipitation, and drought index maps (SPI, PDSI) at various time steps • Reports of lake and reservoir levels, stream flows, snowpack accumulations, water-supply volume forecasts, dugout water levels, pasture conditions (for the Prairies) • The North American Drought Monitor

  17. Drought Monitoring • Satellite and radar measurements can provide solutions to spatial-scale problems associated with drought monitoring • MSC currently uses Special Sensor Microwave Imager (SSMI) to produce SWE maps for the Prairies that are made available to water resource agencies • Time series extends from 1978 through the present, using the brightness temperature standardization of Derksen and Walker (2003).

  18. Drought Prediction • Drought prediction involves anticipating climatic anomalies that produce unusually hot, dry conditions for extended periods • EC currently produces monthly and seasonal forecasts for T & P for lead times of 3, 6, 9, and 12 months • 0 to 3 month forecasts are made using NWP models • Longer lead times use a statistical (CCA) model using SST anomalies over the previous 12 months • Skill higher for cold season and for temperature

  19. Central North America Today 60 40 ~2070 Return Period (years) 20 0 10 15 20 25 30 Length of Dry Spell (days) The frequency and severity of droughts are likely to increase in southern Canada

  20. Future Droughts SPI PDSI

  21. Research Needs 1. A better understanding of the physical causes of drought initiation, persistence, and termination at a variety of spatial and temporal scales • Large-scale atmospheric and oceanic oscillations • Soil moisture anomalies • Moisture sources • Physical causes of multi-year droughts • Drought migration

  22. Research Needs 2. Quantification and assessment of past drought occurrences • Past trends and variability • Drought indices • Paleo-drought studies 3. Better knowledge regarding future drought occurrence • More reliable GCM/RCM output • Improved downscaling methods • Future changes to large-scale circulation patterns

  23. Research Needs 4. Ability to more accurately predict drought onset, intensity, and termination • Improvements in modelling and monitoring of current drought conditions • More reliable short term (seasonal) climate forecast 5. More effective short and long-term adaptation strategies to defend against future droughts

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