dendroclimatology march 28, 2013
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Dendroclimatology March 28, 2013. Tree-ring data are just one of type of many proxies of past climate. Dendroclimatology. Dendroclimatologists are interested in past climate….why? Synoptic climatology –. Climate conditions can be estimated from a variety of natural - PowerPoint PPT PresentationTRANSCRIPT
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DendroclimatologyMarch 28, 2013
DendroclimatologyMarch 28, 2013
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Tree-ring data are just one of type of many proxies of past climate.
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Dendroclimatologists are interested in past climate….why?
Synoptic climatology –
Climate conditions can be estimated from a variety of natural environmental records going back to well before humans existed.
Dendroclimatology
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-Site selection
-Tree age
-Tree shape
-Injured trees or those in the understory are avoided
-Sample depth
-Standardization removes non-climatic trends
-Climate data
Dendroclimatology
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Correlation analysis and Response Function Analysis
• Correlation analysis complements results from response function analysis.
• RFA primarily concerned with temp and precip. Correlation analysis can be done on ALL climate variables
• Range of values = -1.0 < r < +1.0
• Associated with each r-value is its p-value which tests for statistical significance.
• In general, we want p-values less than 0.05, or p < 0.05.
• As in response function analysis, we also analyze months from the previous growing season (why?).
• As in response function analysis, we look for groupings of monthly variables to indicate seasonal response by trees.
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Pearson Correlation Coefficients Prob > |r| under H0: Rho=0 Number of Observations
lmayt ljunt ljult laugt lsept loctt lnovt
-0.08019 -0.03131 -0.34233 -0.16914 -0.29516 -0.09849 -0.02712 0.4941 0.7897 0.0023 0.1414 0.0096 0.4071 0.8173 75 75 77 77 76 73 75
Correlation analysis
• R-values also known as Pearson correlation coefficients
• SAS output below: r-value (top), p-value (middle), n size (bottom)
• How do you interpret negative correlations?
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Dendroclimatology
Primary Variables:- Temperature (ave, min, max)- Precipitation (total)- Palmer Drought Severity Index (PDSI)- Palmer Hydrologic Drought Index (PHDI)
Derived Variables:- El Nino Southern Oscillation (ENSO)- North Atlantic Oscillation (NAO)- Atlantic Multidecadal Oscillation (AMO)- Pacific Decadal Oscillation (PDO)
Teleconnection – the interconnection of physical parameters over long distances
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Drought Reconstruction
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Long term perspective on drought in the American Southeast
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Long term perspective on drought in the American Southeast
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ENSO Reconstruction
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Pacific Decadal Oscillation
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Atlantic Multidecadal Oscillation