1. THE STRUCTURE OF DROUGHT Ronald Stewart University of Manitoba

3. A lot of nothing?

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

5. The Canadian Prairies

6. Mackenzie Saskatchewan 400 500 600 700 850 925 1000 300 -2.0 -3.0 0 1.02.03.0 PRESSURE (hPa) FLUX (1011 kg/Pa/month) VERTICAL MOISTURE FLUX PROFILE Into the Prairies Out of the Prairies

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

8. COMMON VIEW …

9. Drought … Not Too Hot TemperaturePrecipitation Summers of 2000, 2001 and 2002

10. PRECIPITATION-TEMPERATURE ANOMALY Agricultural Years (Sept-Aug) Edmonton

11. Monthly temperature anomalies: agricultural region of the Prairies

12. CLOUD AMOUNT

13. 2001 ___________ 900 km ____________

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

15. CANADIAN PRAIRIES 2002

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

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

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

19. OCCURRENCE OF CALM CONDITIONS

20. DUSTSTORMS 32 major dust storms in Saskatchewan in 2002

21. CANADIAN PRAIRIES 2002 _________ 900 km ___________

22. June 6-9, 2002

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

24. DROUGHT TYPES The sustained lack of precipitation can be linked with different 'types' A drought can go between 'types'

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