Atmospheric vapor and precipitation are not in isotopic equilibrium in a continental mountain environment


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Owners: Jason Mercer
Type: Resource
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Created: Jan 01, 2020 at 10:25 p.m.
Last updated: Apr 13, 2020 at 5:55 p.m.
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Abstract

Isotopic exchange with atmospheric vapor can strongly influence the isotopic ratio of evaporating surface water bodies (e.g., lakes), influencing our understanding of hydrological processes across aquatic and terrestrial environments. Rather than measure the isotopic values of the atmosphere directly, it is much more common to estimate values by assuming equilibrium with local precipitation. This assumption may introduce large error. To date, the pattern and magnitude of this error has been quantified only in a few circumstances. We compared observations of vapor and precipitation isotope values over a four-year record collected in a montane environment in the central Rocky Mountains of North America. We further investigated factors and conditions promoting disequilibrium. Scenario comparisons assessed the impact of theoretical and methodological elements on the accuracy of the equilibrium assumption. We found that the equilibrium assumption was not well supported by direct and continuous observations of vapor isotopes using tower-based laser isotope spectroscopy, particularly during the summer months. Across all scenarios, errors associated with the equilibrium assumption were high, credibly ranging from 14 to 154 ‰ for &delta;<sup>2</sup>H and 1.5 to 16.3‰ for &delta;<sup>18</sup>O. Environmental covariates (e.g., vapor pressure deficit, air pressure) helped explain some of the apparent disequilibrium. Although the equilibrium assumption for estimating atmospheric vapor isotope values may not be applicable in a continental montane environment, our findings highlight opportunities for using direct vapor isotope measurements to better understand vapor sources, air mass mixing, and phase changes over complex mountainous terrain, which in turn may better constrain regional- to global-scale hydrological processes, such as evapotranspiration and water budgets of mountain lakes.

Coverage

Spatial

Coordinate System/Geographic Projection:
WGS 84 EPSG:4326
Coordinate Units:
Decimal degrees
Place/Area Name:
Medicine Bow National Forest
North Latitude
41.3874°
East Longitude
-106.1564°
South Latitude
41.3077°
West Longitude
-106.2407°

Temporal

Start Date: 01/01/2014
End Date: 11/29/2017
Leaflet Map data © OpenStreetMap contributors

Content

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Related Resources

This resource is referenced by A compendium for "Atmospheric vapor and precipitation are not in isotopic equilibrium in a continental mountain environment": https://osf.io/7he4x/
This resource is referenced by The supplemental website: https://wetlandscapes.gitlab.io/mountain-vapor-isotopes/
This resource is referenced by Mercer, JJ, DT Liefert, and DG Williams. 2020. Atmospheric vapor and precipitation are not in isotopic equilibrium in a continental mountain environment. Hydrological Processes. https://doi.org/10.1002/hyp.13775

Credits

Funding Agencies

This resource was created using funding from the following sources:
Agency Name Award Title Award Number
National Science Foundation Wyoming Center for Environmental Hydrology and Geophysics 1208909

Contributors

People or Organizations that contributed technically, materially, financially, or provided general support for the creation of the resource's content but are not considered authors.

Name Organization Address Phone Author Identifiers
John Frank Rocky Mountain Research Station, US Forest Service
John Korfmacher Rocky Mountain Research Station, US Forest Service

How to Cite

Mercer, J. (2020). Atmospheric vapor and precipitation are not in isotopic equilibrium in a continental mountain environment, HydroShare, http://www.hydroshare.org/resource/7c7267d19dc94e1b834d0fc82bdffa50

This resource is shared under the Creative Commons Attribution CC BY.

http://creativecommons.org/licenses/by/4.0/
CC-BY

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