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Rocky Mountain hydroclimate: Holocene variability and the role of insolation, ENSO, and the North American Monsoon

Global and Planetary Change

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DOI: 10.1016/j.gloplacha.2012.05.012

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Abstract

Over the period of instrumental records, precipitation maximum in the headwaters of the Colorado Rocky Mountains has been dominated by winter snow, with a substantial degree of interannual variability linked to Pacific ocean–atmosphere dynamics. High-elevation snowpack is an important water storage that is carefully observed in order to meet increasing water demands in the greater semi-arid region. The purpose here is to consider Rocky Mountain water trends during the Holocene when known changes in earth's energy balance were caused by precession-driven insolation variability. Changes in solar insolation are thought to have influenced the variability and intensity of the El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North American Monsoon and the seasonal precipitation balance between rain and snow at upper elevations. Holocene records are presented from two high elevation lakes located in northwest Colorado that document decade-to-century scale precipitation seasonality for the past ~ 7000 years. Comparisons with sub-tropical records of ENSO indicate that the snowfall-dominated precipitation maxima developed ~ 3000 and 4000 years ago, coincident with evidence for enhanced ENSO/PDO dynamics. During the early-to-mid Holocene the records suggest a more monsoon affected precipitation regime with reduced snowpack, more rainfall, and net moisture deficits that were more severe than recent droughts. The Holocene perspective of precipitation indicates a far broader range of variability than that of the past century and highlights the non-linear character of hydroclimate in the U.S. west.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Rocky Mountain hydroclimate: Holocene variability and the role of insolation, ENSO, and the North American Monsoon
Series title:
Global and Planetary Change
DOI:
10.1016/j.gloplacha.2012.05.012
Volume
92-93
Year Published:
2012
Language:
English
Publisher:
Elsevier
Contributing office(s):
Geosciences and Environmental Change Science Center
Description:
11 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Global and Planetary Change
First page:
198
Last page:
208
Number of Pages:
11
Country:
United States
State:
Colorado
Other Geospatial:
Rocky Mountains