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The continuum of hydroclimate variability in western North America during the last millennium

Journal of Climate

By:
, , , , , , , and
DOI: 10.1175/JCLI-D-11-00732.1

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Abstract

The distribution of climatic variance across the frequency spectrum has substantial importance for anticipating how climate will evolve in the future. Here we estimate power spectra and power laws (ß) from instrumental, proxy, and climate model data to characterize the hydroclimate continuum in western North America (WNA). We test the significance of our estimates of spectral densities and ß against the null hypothesis that they reflect solely the effects of local (non-climate) sources of autocorrelation at the monthly timescale. Although tree-ring based hydroclimate reconstructions are generally consistent with this null hypothesis, values of ß calculated from long-moisture sensitive chronologies (as opposed to reconstructions), and other types of hydroclimate proxies, exceed null expectations. We therefore argue that there is more low-frequency variability in hydroclimate than monthly autocorrelation alone can generate. Coupled model results archived as part of the Climate Model Intercomparison Project 5 (CMIP5) are consistent with the null hypothesis and appear unable to generate variance in hydroclimate commensurate with paleoclimate records. Consequently, at decadal to multidecadal timescales there is more variability in instrumental and proxy data than in the models, suggesting that the risk of prolonged droughts under climate change may be underestimated by CMIP5 simulations of the future.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The continuum of hydroclimate variability in western North America during the last millennium
Series title:
Journal of Climate
DOI:
10.1175/JCLI-D-11-00732.1
Volume
26
Year Published:
2013
Language:
English
Publisher:
American Meteorological Society
Contributing office(s):
Northern Rocky Mountain Science Center
Description:
16 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Climate
First page:
5863
Last page:
5878
Country:
United States