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Title: Vegetation controls on surface heat flux partitioning, and land-atmosphere coupling

Abstract

Here, we provide observational evidence that land-atmosphere coupling is underestimated by a conventional metric defined by the correlation between soil moisture and surface evaporative fraction (latent heat flux normalized by the sum of sensible and latent heat flux). Land-atmosphere coupling is 3 times stronger when using leaf area index as a correlate of evaporative fraction instead of soil moisture, in the Southern Great Plains. The role of vegetation was confirmed using adjacent flux measurement sites having identical atmospheric forcing but different vegetation phenology. Transpiration makes the relationship between evaporative fraction and soil moisture nonlinear and gives the appearance of weak coupling when using linear soil moisture metrics. Regions of substantial coupling extend to semiarid and humid continental climates across the United States, in terms of correlations between vegetation metrics and evaporative fraction. The hydrological cycle is more tightly constrained by the land surface than previously inferred from soil moisture.

Authors:
 [1];  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1470995
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 42; Journal Issue: 21; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES

Citation Formats

Williams, Ian N., and Torn, Margaret S. Vegetation controls on surface heat flux partitioning, and land-atmosphere coupling. United States: N. p., 2015. Web. doi:10.1002/2015GL066305.
Williams, Ian N., & Torn, Margaret S. Vegetation controls on surface heat flux partitioning, and land-atmosphere coupling. United States. doi:10.1002/2015GL066305.
Williams, Ian N., and Torn, Margaret S. Fri . "Vegetation controls on surface heat flux partitioning, and land-atmosphere coupling". United States. doi:10.1002/2015GL066305. https://www.osti.gov/servlets/purl/1470995.
@article{osti_1470995,
title = {Vegetation controls on surface heat flux partitioning, and land-atmosphere coupling},
author = {Williams, Ian N. and Torn, Margaret S.},
abstractNote = {Here, we provide observational evidence that land-atmosphere coupling is underestimated by a conventional metric defined by the correlation between soil moisture and surface evaporative fraction (latent heat flux normalized by the sum of sensible and latent heat flux). Land-atmosphere coupling is 3 times stronger when using leaf area index as a correlate of evaporative fraction instead of soil moisture, in the Southern Great Plains. The role of vegetation was confirmed using adjacent flux measurement sites having identical atmospheric forcing but different vegetation phenology. Transpiration makes the relationship between evaporative fraction and soil moisture nonlinear and gives the appearance of weak coupling when using linear soil moisture metrics. Regions of substantial coupling extend to semiarid and humid continental climates across the United States, in terms of correlations between vegetation metrics and evaporative fraction. The hydrological cycle is more tightly constrained by the land surface than previously inferred from soil moisture.},
doi = {10.1002/2015GL066305},
journal = {Geophysical Research Letters},
number = 21,
volume = 42,
place = {United States},
year = {2015},
month = {11}
}

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Cited by: 17 works
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