TWO
             SOLITUDES


how seasonality biases
      drought records from tree rings
TWO
             SOLITUDES


how seasonality biases
      drought records from tree rings
why are Canadian streamflow reconstructions so lousy?
100%




            80%




            60%
explained
 variance
            40%




            20%




             0%

...
100%



                                                       Woodhouse et al., 2006
                                 Mek...
100%



                                                                                                       Woodhouse e...
why are Canadian tree rings not connected to climate modes?
Janice Lough and Hal Fritts
The Southern Oscillation and tree rings: 1600 - 1961
Journal of Applied Meteorology 24, 1985

...
Prairie ringwidth records
138
Significant correlation with ENSO
4
Expected from random chance
6.9
seasonality
Trees, seasonality and climate forcings
The southwestern US
Trees, seasonality and climate forcings
The Canadian Prairies
DROUGHT AND SEASONALITY
How does the connection between reconstructed drought
1
and seasonal precipitation vary across Nor...
DROUGHT AND SEASONALITY
    How does the connection between reconstructed drought
1   and seasonal precipitation vary acro...
The North American
                                                Drought Atlas




Cook et al., 2007, Earth Science Revi...
Cook et al., 2007, Earth Science Reviews
CORRELATION
COMPOSITES
COHERENCE
PART ONE
tree rings, drought and seasonality
significant (α=0.05)
instrumental   tree rings
SUMM ER PRECIP ITAT ION
WINTER PRECIPITAT ION
do tree rings replicate these patterns?
+
summer

mixed

winter
DOMINANT
    not

    exclusive
“
...the regional summer precipitation signal is strong in
Pseudotsuga menziesii latewood-width [in southeastern
Arizona]....
Medicine Hat, Alberta




Source: Environment Canada, Adjusted Historical Canadian Climate Data, 1895 – 2006
Prairie ringwidth records
138
Significant correlation with ENSO
4
Expected from random chance
6.9                          ...
ENSO and winter precipitation
PART TWO
drought records and climate modes
ENSO
PDSI
from tree rings
                  PDO
                  AMO
are these signals present in reconstructed drought?
Julia Cole and Ed Cook
The changing relationship between ENSO variability
and moisture balance in the continental United S...
ENSO
PDSI
from tree rings
                  PDO
                  AMO
COMPOSITES
where is it wet or dry when ENSO is strong?
ENSO
PDSI
from tree rings
                  PDO
                  AMO
LOW
 frequency
LOW FREQUENCIES (>7yr)
                        TREE-RINGS and PDO



 0.5




0.25




       mean squared                ...
LOW FREQUENCIES (>7yr)
                        TREE-RINGS and PDO



 0.5




0.25




       mean squared                ...
3                                 Mexican PDSI   10


2
                                                 5
1


0          ...
3      PDO index                   Mexican PDSI   10


2
                                                  5
1


0        ...
ENSO
PDSI
from tree rings
                  PDO
                  AMO
SEAS ONALITY AND D ROUGHT
summer

mixed

winter
IMPLICATIONS




 1590s
IMPLICATIONS



        what/where   OK
IMPLICATIONS



        what/where   OK

   what/where/why    NOT OK
IMPLICATIONS

 tree ring                model output




               Celine Herwiejer, Richard Seager and Ed Cook
     ...
summer

mixed

winter
M A N Y TH AN KS

    Dave Meko
     Ed Cook
     Hal Fritts
     Toby Ault
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
Two solitudes - how seasonality biases drought from tree rings
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Two solitudes - how seasonality biases drought from tree rings

  1. 1. TWO SOLITUDES how seasonality biases drought records from tree rings
  2. 2. TWO SOLITUDES how seasonality biases drought records from tree rings
  3. 3. why are Canadian streamflow reconstructions so lousy?
  4. 4. 100% 80% 60% explained variance 40% 20% 0% Canada USA
  5. 5. 100% 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% 0% Canada USA
  6. 6. 100% 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 explained Saskatchewan River Beriault and Sauchyn, 2006 Churchill River variance Bonin and Burn, 2005 Athabasca River 40% Watson and Luckman, 2005 Gedalof et al., 2007 Bow River Columbia River 20% 0% Canada USA
  7. 7. why are Canadian tree rings not connected to climate modes?
  8. 8. Janice Lough and Hal Fritts The Southern Oscillation and tree rings: 1600 - 1961 Journal of Applied Meteorology 24, 1985 Roseanne D’Arrigo and Gordon Jacoby A thousand year record of northwestern New Mexico winter precipitation reconstructed from tree rings and its relation to El Niño and the Southern Oscillation The Holocene 1, 1991 David Stahle and collaborators Experimental dendroclimatic reconstruction of the Southern Oscillation Stahle et al., 1998 Bulletin of the American Meteorological Society 79, 1998
  9. 9. Prairie ringwidth records 138 Significant correlation with ENSO 4 Expected from random chance 6.9
  10. 10. seasonality
  11. 11. Trees, seasonality and climate forcings The southwestern US
  12. 12. Trees, seasonality and climate forcings The Canadian Prairies
  13. 13. DROUGHT AND SEASONALITY How does the connection between reconstructed drought 1 and seasonal precipitation vary across North America?
  14. 14. DROUGHT AND SEASONALITY How does the connection between reconstructed drought 1 and seasonal precipitation vary across North America? CLIMATE MODES AND TREE RINGS In which regions are drought reconstructions most strongly 2 connected to remote climate forcings (ENSO, PDO, AMO)?
  15. 15. The North American Drought Atlas Cook et al., 2007, Earth Science Reviews
  16. 16. Cook et al., 2007, Earth Science Reviews
  17. 17. CORRELATION COMPOSITES COHERENCE
  18. 18. PART ONE tree rings, drought and seasonality
  19. 19. significant (α=0.05)
  20. 20. instrumental tree rings
  21. 21. SUMM ER PRECIP ITAT ION
  22. 22. WINTER PRECIPITAT ION
  23. 23. do tree rings replicate these patterns?
  24. 24. +
  25. 25. summer mixed winter
  26. 26. DOMINANT not exclusive
  27. 27. “ ...the regional summer precipitation signal is strong in Pseudotsuga menziesii latewood-width [in southeastern Arizona]. David Meko and Chris Baisan Pilot study of latewood-width of conifers as an indicator of variability of summer rainfall in the North American monsoon region International Journal of Climatology 21, 2001
  28. 28. Medicine Hat, Alberta Source: Environment Canada, Adjusted Historical Canadian Climate Data, 1895 – 2006
  29. 29. Prairie ringwidth records 138 Significant correlation with ENSO 4 Expected from random chance 6.9 45
  30. 30. ENSO and winter precipitation
  31. 31. PART TWO drought records and climate modes
  32. 32. ENSO PDSI from tree rings PDO AMO
  33. 33. are these signals present in reconstructed drought?
  34. 34. Julia Cole and Ed Cook The changing relationship between ENSO variability and moisture balance in the continental United States Geophysical Research Letters 25, 1998
  35. 35. ENSO PDSI from tree rings PDO AMO
  36. 36. COMPOSITES where is it wet or dry when ENSO is strong?
  37. 37. ENSO PDSI from tree rings PDO AMO
  38. 38. LOW frequency
  39. 39. LOW FREQUENCIES (>7yr) TREE-RINGS and PDO 0.5 0.25 mean squared 61 0 coherence
  40. 40. LOW FREQUENCIES (>7yr) TREE-RINGS and PDO 0.5 0.25 mean squared 61 0 coherence
  41. 41. 3 Mexican PDSI 10 2 5 1 0 0 -1 -5 -2 -3 62 -10 1900 1920 1940 1960 1980 2000
  42. 42. 3 PDO index Mexican PDSI 10 2 5 1 0 0 -1 -5 -2 -3 63 -10 1900 1920 1940 1960 1980 2000
  43. 43. ENSO PDSI from tree rings PDO AMO
  44. 44. SEAS ONALITY AND D ROUGHT
  45. 45. summer mixed winter
  46. 46. IMPLICATIONS 1590s
  47. 47. IMPLICATIONS what/where OK
  48. 48. IMPLICATIONS what/where OK what/where/why NOT OK
  49. 49. IMPLICATIONS tree ring model output Celine Herwiejer, Richard Seager and Ed Cook North American droughts of the mid to late nineteenth century: a history, simulation and implication for Mediaeval drought The Holocene 16, 2006
  50. 50. summer mixed winter
  51. 51. M A N Y TH AN KS Dave Meko Ed Cook Hal Fritts Toby Ault

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