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THE STRUCTURE OF DROUGHT

This study by Ronald Stewart explores the internal features of drought through vertical moisture flux profiles in the Canadian Prairies. It covers factors like precipitation anomalies, water and energy cycling, occurrence of dust storms, and drought types.

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THE STRUCTURE OF DROUGHT

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  1. THE STRUCTURE OF DROUGHT Ronald Stewart University of Manitoba

  2. A lot of nothing?

  3. OBJECTIVE To illustrate some aspects of drought's 'structure' (internal features)

  4. The CanadianPrairies

  5. VERTICAL MOISTURE FLUX PROFILE 300 PRESSURE (hPa) 400 500 Out of the Prairies Into the Prairies 600 Mackenzie 700 Saskatchewan 850 925 1000 0 -2.0 -1.0 1.0 2.0 3.0 -3.0 FLUX (1011 kg/Pa/month)

  6. --- PDSI- Palmer Drought Severity Index  SPI- Standardized Precipitation Index

  7. COMMON VIEW …

  8. Precipitation Temperature Drought … Not Too Hot Summers of 2000, 2001 and 2002

  9. PRECIPITATION-TEMPERATURE ANOMALYAgricultural Years (Sept-Aug) Edmonton

  10. Monthly temperature anomalies: agricultural region of the Prairies 

  11. CLOUD AMOUNT

  12. 2001 ___________ 900 km ____________

  13. WATER AND ENERGY CYCLING Many factors affect the cycling of water and energy during drought

  14. CANADIAN PRAIRIES2002

  15. Daily Precipitation Amounts Low precipitation event: < 10 mm Climatology Low precipitation events: 52% of total Sub-drought 2002 Low precipitation events: 60% of total

  16. VIRGA Summer 2002 - Edmonton Precipitation Amount Reduction (%)    -49 Precipitation (h)                                   123   Virga (h)                                              130 

  17. PRECIPITATION RATE • Cold Lake 24 April 2003 • Hail and rain • 243% of monthly average accumulation 45 dBZ maximum • Cold Lake 1-3 October 2005 •  Rain and snow • 143% of monthly average accumulation 20 dBZ maximum

  18. OCCURRENCE OF CALM CONDITIONS

  19. DUSTSTORMS  32 major dust storms in Saskatchewan in 2002

  20. CANADIAN PRAIRIES2002 _________ 900 km ___________

  21. June 6-9, 2002

  22. ___ 900 km __ Palmer Drought Severity Index (PDSI) for agricultural years with severe drought

  23. No precipitation       ... or ... Sprinkles Virga Chance of catastrophic rain Steady rain Torrential rate Hot Cold Windy Calm Dusty Clear Cloud-free Cloudy DROUGHT TYPES • The sustained lack of precipitation can be linked with different 'types' • A drought can go between 'types'

  24. SUMMARY Drought has spatial and temporal 'structure' One can think of it as being of various 'types' Understanding drought needs to consider such features

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