Rhythm Or Rumble

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St. George, S. and Ault, T.R. 2011. Temporal instability of the energetic decadal pattern in winter precipitation observed along the central Pacific Coast, USA. Annual Meeting of the American Association of Geographers, Seattle, Washington, April 13 - 16, 2011.

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Rhythm Or Rumble

  1. 1. RHYTHM OR RUMBLE? TEMPORAL INSTABILITY OF THE ENERGETIC DECADAL PATTERN IN WINTER PRECIPITATION OBSERVED ALONG THE CENTRAL PACIFIC COAST, USA
  2. 2. Toby Ault University of Arizona
  3. 3. DECADALVARIABILITY
  4. 4. “The decadal time scale offersa critical bridge for informing ”adaptation strategies asclimate varies and changes. Meehl et al., BAMS, 2009
  5. 5. Photograph: Andes Ali
  6. 6. A rhythm consists of regular and recurring pa erns in sound and silence.Photograph: Bala
  7. 7. Alternatively...
  8. 8. A rumble is a form of low-frequency noisecreated by the bearings inside a turntable.
  9. 9. GEOGRAPHY
  10. 10. Central Pacific Coast
  11. 11. Photograph: Franklin Hunting
  12. 12. Decadal ‘hotspots’ in winter precipitation 0% 10% 20% 30% varianceAult and St. George, 2010
  13. 13. RHYTHM RUMBLE?
  14. 14. RHYTHM RUMBLE? n
  15. 15. QUESTION #1Can tree-ring records track the decadal componentof regional winter precipitation?
  16. 16. QUESTION #2Is the recent, strong decadal pa ern a regular featureof the region’s winter climate?
  17. 17. STEP ONEObtain all ring-width measurements within thecentral Pacific Coast region from the ITRDB.
  18. 18. tree-ring width recordsInternational Tree-Ring Databank
  19. 19. STEP TWOUse a modified version of singular spectrum analysis to emphasize the observed decadal pa ern.
  20. 20. St. George, S. and Ault. T.R. (in press). Is energetic decadal variabilitya stable feature of the central Pacific Coast’s winter climate?Journal of Geophysical Research.
  21. 21. STEP THREE Identify those tree-ring chronologies that areoptimal proxies for the observed decadal pa ern.
  22. 22. Photograph: Dan Griffin
  23. 23. “If a significance test fails in the forest does anybody count that as a unsuccessful trial?”Carlo Emilio Bonferroni 1892 - 1960
  24. 24. decadal target
  25. 25. decadal targetdecadal ‘noise’
  26. 26. 7 false positives10 000 trials
  27. 27. STEP FOURApply the same filter to estimate the behavior of the decadal pa ern back in time.
  28. 28. reallynot that decadaldecadal
  29. 29. MAIN FINDINGThe energetic decadal pa ern in winter precipitation is a relatively recent feature.
  30. 30. RHYTHM RUMBLE?
  31. 31. RHYTHM RUMBLE?
  32. 32. DOESHIGHVARIANCE NOT NECESSARILY DECADAL SIGNAL EQUAL

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