During the fall of 2011, Surface Processes class in the Department of Geology at the University of Cincinnati undertook a series of measurements on one of a pair of former ponds that had been used as make-up water for the Miami & Erie Canal [map]. To help understand the climate history of the site, the class made a series of measurements of tree ring thickness. The longest record was retrieved from an ash tree being cut down on Resor Ave, about 1 mile south of the site.

Clifton tree ring data

Ring thickness shows cyclic behavior on a 5-6 year time scale, similar to that seen in other climate records for Cincinnati. To evaluate these cycles, we ran time series analysis using the program PAST:

tree ring time series

The periods revealed have similarities to those for El Nino -- Southern Oscillation intensities (see table). It appears likely that the 6.6 and 7.3 year cycles in the tree ring data are a response to ENSO events, but that other events also have considerable influence over rainfall patterns. For example the 7.3 and 8.3 year tree ring cycles are do not correspond well to ENSO frequencies.

 

Time Series Spectra for Cinti Climate (1950-2010)
Cinti precipitation
ENSO events
Tree rings (1885-2005)
Period
Power
Period
Power
Period
Power
3.5
1.42
3.7
4.46
3.6
0.05
4.0
0.69
4.1
1.49
4.3
0.78
4.7
0.43
4.9
4.52
5.1
0.72
5.7
8.94
5.6
2.43
6.1
1.59
6.6
2.70
6.4
2.41
6.6
1.21
7.9
1.81
7.5
0.73
7.3
1.48
9.2
0.20
8.9
1.07
8.3
2.03
11.3
1.49
11.6
1.97
12.0
2.56
20.3
1.53
18.7
8.44
30.5
0.78
38.2
14.71

 

ENSO events and Cincinnati weather

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