DendroclimatologyMarch 28, 2013

DendroclimatologyMarch 28, 2013

Tree-ring data are just one of type of many proxies of past climate.

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

-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

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.

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?

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

Drought Reconstruction

Long term perspective on drought in the American Southeast

Long term perspective on drought in the American Southeast

ENSO Reconstruction

Pacific Decadal Oscillation

Atlantic Multidecadal Oscillation