Title: Estimation of subsurface porosities and thermal conductivities of polygonal tundra by coupled inversion of electrical resistivity, temperature, and moisture content data

Abstract

Studies indicate greenhouse gas emissions following permafrost thaw will amplify current rates of atmospheric warming, a process referred to as the permafrost carbon feedback. However, large uncertainties exist regarding the timing and magnitude of the permafrost carbon feedback, in part due to uncertainties associated with subsurface permafrost parameterization and structure. Development of robust parameter estimation methods for permafrost-rich soils is becoming urgent under accelerated warming of the Arctic. Improved parameterization of the subsurface properties in land system models would lead to improved predictions and a reduction of modeling uncertainty. In this work we set the groundwork for future parameter estimation (PE) studies by developing and evaluating a joint PE algorithm that estimates soil porosities and thermal conductivities from time series of soil temperature and moisture measurements and discrete in-time electrical resistivity measurements. The algorithm utilizes the Model-Independent Parameter Estimation and Uncertainty Analysis toolbox and coupled hydrological–thermal–geophysical modeling. We test the PE algorithm against synthetic data, providing a proof of concept for the approach. We use specified subsurface porosities and thermal conductivities and coupled models to set up a synthetic state, perturb the parameters, and then verify that our PE method is able to recover the parameters and synthetic state. Tomore » evaluate the accuracy and robustness of the approach we perform multiple tests for a perturbed set of initial starting parameter combinations. In addition, we varied types and quantities of data to better understand the optimal dataset needed to improve the PE method. The results of the PE tests suggest that using multiple types of data improve the overall robustness of the method. Our numerical experiments indicate that special care needs to be taken during the field experiment setup so that (1) the vertical distance between adjacent measurement sensors allows the signal variability in space to be resolved and (2) the longer time interval between resistivity snapshots allows signal variability in time to be resolved.« less

Authors:

Jafarov, Elchin E.  ^[1];

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Harp, Dylan R.  ^[1];

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Coon, Ethan T. ^[2]; Dafflon, Baptiste  ^[3];

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Tran, Anh Phuong ^[4]; Atchley, Adam L.  ^[1];

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Lin, Youzuo ^[1]; Wilson, Cathy J.  ^[1]

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• Search DOE PAGES for ORCID "0000-0001-9896-0912"
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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Water Research Inst., Hanoi (Vietnam)

Publication Date:

2020-01-15

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC). Biological and Environmental Research (BER) (SC-23)

OSTI Identifier:

1599848

Alternate Identifier(s):

OSTI ID: 1606940; OSTI ID: 1659183

Report Number(s):

LA-UR-19-23188
Journal ID: ISSN 1994-0424; ark:/13030/qt7jr302k2

Grant/Contract Number:  

AC02-05CH11231; AC05-00OR22725; 89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

The Cryosphere (Online)

Additional Journal Information:

Journal Name: The Cryosphere (Online); Journal Volume: 14; Journal Issue: 1; Journal ID: ISSN 1994-0424

Publisher:

European Geosciences Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Computer Science; Earth Sciences; Mathematics