The seasonality of moisture-sensitive tree-ring records

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Presentation given at PAGES 2K meeting in Tucson, Arizona, October 28, 2011.

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The seasonality of moisture-sensitive tree-ring records

  1. 1. THESEASONALITYOF MOISTURE-SENSITIVE TREE-RING RECORDS
  2. 2. MY DISSERTATION PROPOSAL“...this project will establish a new network of moisture-sensitive tree-ring sites within the WRB that will allowresearchers to estimate hydroclimatic conditions in thebasin during the past 200 – 500 years.”
  3. 3. XMY DISSERTATION PROPOSAL“...this project will establish a new network of moisture-sensitive tree-ring sites within the WRB that will allowresearchers to estimate hydroclimatic conditions in thebasin during the past 200 – 500 years.”
  4. 4. 100% MORE CERTAIN 80% 60%explained variance 40% 20% LESS CERTAIN 0% Canada USA
  5. 5. 100% MORE CERTAIN Woodhouse et al., 2006 Meko et al., 2001 80% Sacramento River Upper Colorado River Meko et al., 2007 Colorado River Woodhouse, 2007 Middle Boulder Creek 60%explained variance 40% 20% LESS CERTAIN 0% Canada USA
  6. 6. 100% MORE CERTAIN Woodhouse et al., 2006 Meko et al., 2001 80% Sacramento River Upper Colorado River Meko et al., 2007 Colorado River Woodhouse, 2007 Middle Boulder Creek 60% Case and MacDonald, 2003 Saskatchewan Riverexplained Beriault and Sauchyn, 2006 Churchill River Bonin and Burn, 2005 variance Athabasca River 40% Watson and Luckman, 2005 Gedalof et al., 2007 Bow River Columbia River 20% LESS CERTAIN 0% Canada USA
  7. 7. SEASONALITY
  8. 8. QUESTIONWhat is the seasonality of moisture-sensitivetree-ring records across North America?
  9. 9. Source: David Stahle
  10. 10. QUESTION droughtWhat is the seasonality of moisture-sensitivetree-ring records across North America?
  11. 11. NORTH AMERICAN DROUGHT ATLAS h p://www.ncdc.noaa.gov/paleo/pdsi.html
  12. 12. Source: Cook et al., Earth Science Reviews, 2007
  13. 13. INSTRUMENTAL PDSI WINTER SUMMERtotal precipitation total precipitation
  14. 14. INSTRUMENTAL TREE-RING PDSI PDSI WINTER SUMMER WINTER SUMMERtotal precipitation total precipitation total precipitation total precipitation
  15. 15. Point-to-point correlations, Summer Precipitation & Summer PDSI (Instrumental)St. George et al., The Holocene, 2011
  16. 16. 0.0 0.2 0.4 0.6Point-to-point correlations, Summer Precipitation & Summer PDSISt. George et al., The Holocene, 2010
  17. 17. 0.0 0.2 0.4 0.6Point-to-point correlations, Winter Precipitation & Summer PDSISt. George et al., The Holocene, 2010
  18. 18. Seasonal precipitation ‘bias’ of NADASt. George et al., The Holocene, 2010
  19. 19. WINTER-SENSITIVE SUMMER-SENSITIVE RECORDS RECORDS
  20. 20. WINTER-SENSITIVE SUMMER-SENSITIVE RECORDS RECORDS HIGH spatial coherence STRONG connections to remote forcings GOOD hydrological proxy
  21. 21. WINTER-SENSITIVE SUMMER-SENSITIVE RECORDS RECORDS HIGH spatial coherence LOW spatial coherence STRONG connections to MODEST connections to remote forcings remote forcings GOOD hydrological proxy POOR hydrological proxy
  22. 22. EL NIÑ0SOUTHERN OSCILLATION
  23. 23. ENSO (the Cold Tongue Index) correlated against reconstructed summer PDSISt. George et al., The Holocene, 2010
  24. 24. QUESTION droughtWhat is the seasonality of moisture-sensitivetree-ring records across North America?
  25. 25. Seasonal precipitation ‘bias’ of NADASt. George et al., The Holocene, 2010
  26. 26. GENERAL TENDENCY WITHMORE AND MORE EXCEPTIONS
  27. 27. QUESTIONWhat is the seasonality of moisture-sensitivetree-ring records across North America?
  28. 28. Source: David Stahle
  29. 29. 1747The International Tree-Ring Databank houses ring-width chronologies from North America
  30. 30. QUESTIONAre our analytical methods appropriatewhen we apply them to very large datasets?
  31. 31. COMMON ‘OPTIMAL’PATTERNS PREDICTORS
  32. 32. Bürger, Science, 2007
  33. 33. “ This method of selecting proxies by screening a potentially large number of candidates for positive correlations runs the danger of choosing a proxy by chance. Gerd Bürger ” Science 2007
  34. 34. Carlo Emilio Bonferroni 1892 - 1960
  35. 35. Source: David Stahle
  36. 36. 1747 RING-WIDTHCHRONOLOGIES
  37. 37. 1747 RING-WIDTH 0.95 SIGNIFICANCECHRONOLOGIES LEVEL
  38. 38. 1747 RING-WIDTH 0.95 ➔ SIGNIFICANCE 87 CHRONOLOGIESCHRONOLOGIES LEVEL THAT CORRELATE WITH JUST ABOUT ANYTHING
  39. 39. 2 approaches that might help
  40. 40. 1We should test our models against noise.
  41. 41. Decadal ‘hotspots’ in winter precipitation 0% 10% 20% 30% varianceAult and St. George, Journal of Climate, 2010
  42. 42. tree-ring width recordsInternational Tree-Ring Databank St. George and Ault, JGR-A, 2011
  43. 43. Carlo Emilio Bonferroni 1892 - 1960
  44. 44. Source: Michael Koukoullis
  45. 45. decadal targetdecadal ‘noise’ St. George and Ault, JGR-A, 2011
  46. 46. 2We need to use all the data we have.
  47. 47. Source: David Stahle
  48. 48. QUESTION the entire set ofWhat is the seasonality of moisture-sensitivetree-ring records across North America?

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