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Title: Mathematical Modelling of Arctic Polygonal Tundra with Ecosys: 2. Microtopography Determines How CO 2 and CH 4 Exchange Responds to Changes in Temperature and Precipitation

Abstract

Differences of surface elevation in arctic polygonal landforms cause spatial variation in soil water contents (θ), active layer depths (ALD), and thereby in CO 2 and CH 4 exchange. In this paper, we test hypotheses in ecosys for topographic controls on CO 2 and CH 4 exchange in trough, rim, and center features of low- and flat-centered polygons (LCP and FCP) against chamber and eddy covariance (EC) measurements during 2013 at Barrow, Alaska. Larger CO 2 influxes and CH 4 effluxes were measured with chambers and modeled with ecosys in LCPs than in FCPs and in lower features (troughs) than in higher (rims) within LCPs and FCPs. Spatially aggregated CO 2 and CH 4 fluxes from ecosys were significantly correlated with EC flux measurements. Lower features were modeled as C sinks (52–56 g C m -2 yr -1) and CH 4 sources (4–6 g C m -2 yr -1), and higher features as near C neutral (-2–15 g C m -2 yr -1) and CH 4 neutral (0.0–0.1 g C m -2 yr -1). Much of the spatial and temporal variations in CO 2 and CH 4 fluxes were modeled from topographic effects on water and snow movement and therebymore » on θ, ALD, and soil O 2 concentrations. Model results forced with meteorological data from 1981 to 2015 indicated increasing net primary productivity in higher features and CH 4 emissions in some lower and higher features since 2008, attributed mostly to recent rises in precipitation. Finally, small-scale variation in surface elevation causes large spatial variation of greenhouse gas (GHG) exchanges and therefore should be considered in estimates of GHG exchange in polygonal landscapes.« less

Authors:
 [1];  [2];  [2]; ORCiD logo [2];  [2]
  1. Univ. of Alberta, Edmonton, AB (Canada). Dept. of Renewable Resources
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Science Division
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:
1433102
Alternate Identifier(s):
OSTI ID: 1414484
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Biogeosciences
Additional Journal Information:
Journal Volume: 122; Journal Issue: 12; Journal ID: ISSN 2169-8953
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; greenhouse gas exchange; modeling; ecosys; polygonal tundra; microtopography

Citation Formats

Grant, R. F., Mekonnen, Z. A., Riley, W. J., Arora, B., and Torn, M. S. Mathematical Modelling of Arctic Polygonal Tundra with Ecosys: 2. Microtopography Determines How CO2 and CH4 Exchange Responds to Changes in Temperature and Precipitation. United States: N. p., 2017. Web. doi:10.1002/2017JG004037.
Grant, R. F., Mekonnen, Z. A., Riley, W. J., Arora, B., & Torn, M. S. Mathematical Modelling of Arctic Polygonal Tundra with Ecosys: 2. Microtopography Determines How CO2 and CH4 Exchange Responds to Changes in Temperature and Precipitation. United States. doi:10.1002/2017JG004037.
Grant, R. F., Mekonnen, Z. A., Riley, W. J., Arora, B., and Torn, M. S. Fri . "Mathematical Modelling of Arctic Polygonal Tundra with Ecosys: 2. Microtopography Determines How CO2 and CH4 Exchange Responds to Changes in Temperature and Precipitation". United States. doi:10.1002/2017JG004037.
@article{osti_1433102,
title = {Mathematical Modelling of Arctic Polygonal Tundra with Ecosys: 2. Microtopography Determines How CO2 and CH4 Exchange Responds to Changes in Temperature and Precipitation},
author = {Grant, R. F. and Mekonnen, Z. A. and Riley, W. J. and Arora, B. and Torn, M. S.},
abstractNote = {Differences of surface elevation in arctic polygonal landforms cause spatial variation in soil water contents (θ), active layer depths (ALD), and thereby in CO2 and CH4 exchange. In this paper, we test hypotheses in ecosys for topographic controls on CO2 and CH4 exchange in trough, rim, and center features of low- and flat-centered polygons (LCP and FCP) against chamber and eddy covariance (EC) measurements during 2013 at Barrow, Alaska. Larger CO2 influxes and CH4 effluxes were measured with chambers and modeled with ecosys in LCPs than in FCPs and in lower features (troughs) than in higher (rims) within LCPs and FCPs. Spatially aggregated CO2 and CH4 fluxes from ecosys were significantly correlated with EC flux measurements. Lower features were modeled as C sinks (52–56 g C m-2 yr-1) and CH4 sources (4–6 g C m-2 yr-1), and higher features as near C neutral (-2–15 g C m-2 yr-1) and CH4 neutral (0.0–0.1 g C m-2 yr-1). Much of the spatial and temporal variations in CO2 and CH4 fluxes were modeled from topographic effects on water and snow movement and thereby on θ, ALD, and soil O2 concentrations. Model results forced with meteorological data from 1981 to 2015 indicated increasing net primary productivity in higher features and CH4 emissions in some lower and higher features since 2008, attributed mostly to recent rises in precipitation. Finally, small-scale variation in surface elevation causes large spatial variation of greenhouse gas (GHG) exchanges and therefore should be considered in estimates of GHG exchange in polygonal landscapes.},
doi = {10.1002/2017JG004037},
journal = {Journal of Geophysical Research. Biogeosciences},
number = 12,
volume = 122,
place = {United States},
year = {Fri Nov 17 00:00:00 EST 2017},
month = {Fri Nov 17 00:00:00 EST 2017}
}

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