Download Climate Change

Regional Climate Change Detection
 What is a climate?
 How does one define a climate in terms of
measured variables?
 After defining it, how does one measure
actual change in a statically defensible
manner. Most of local climate change is
simply assumed to be occurring because
global change is occurring
Anecdotal Evidence Often Used
 More frequent extreme-heat days
 A longer growing season
 An increase in heavy rainfall events
 Earlier breakup of winter ice on lakes and
rivers
 Earlier spring snowmelt resulting in earlier
high spring river flows
 Less precipitation falling as snow and more
as rain
 Reduced snowpack and increased snow
density
Use an Indexing Method
 Climate is largely a monthly/seasonal
phenomena – not annual
 Take a weather site and say it has 100 years
of data for all 12 months and pick a variable
like max temperature. Use all 100 months of
January to compose the average max.
 For each month then in each year, compute
the Z-score for that month/year
 Z-Score = (x - µ) / 
Now Generate a Composite Index
 NEIyr = (Zmxyr + Zmnyr + Zrnyr + Zswyr) / 4
 Can then weight each of the 4Z’s
 The result is a wave form some given site for
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Vermont SiteMinTemp
'432769'
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INDEX
one of the Z parameters
This form of Indexing
 Is identical to the approach used for the Stock
Market; what matters is the behavior over
time of the relative amplitude of the Index.
Weighting the Indicators:
 WMAX 0.25 0.25 0.25 0.25 (equal)
 WGD1
0.4 0.4 0.1 0.1 (emphasize temp)
 WGD2
0.2 0.1 0.6 0.7 (emphasize rain)
 Just try all kinds of combinations: Dick with
the data!
 There is no “right” way to do this just a
consistent way.
Sum up all the good stations
Annual Northeast Climate Index Comparisons for All Variables Combined
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Warm and Wet
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INDEX
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NEI
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Linear(NEI)
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Cool and Dry
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Deconvolve the parameters
Define the Index Seasonally:
Each Arrow Is separated by Exactly 40 years
Experiment with Weights:
The Pacific Northwest Index
Predict the Future
Cool Wet To Return in 2000
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The RPNI (Pacific Northwest)
RPNI 20 Sites
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Annual RPNI