U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights


An Improved Numerical Method for Solving Depth-Resolved Biogeochemical Models
Published: February 20, 2018
Posted: April 10, 2018

A method of alternating characteristics with application to advection-dominated environmental systems.

The Science
Scientists at Lawrence Berkeley National Lab (LBNL) propose a numerical integration method, termed the method of alternating characteristics (MAC), to efficiently and accurately solve systems of partial differential equations that arise in modeling environmental processes. They highlight the advantages of the MAC with emphasis on advection-dominated environmental systems with biogeochemical reactions.

The Impact
The proposed method is uniquely suited for solving depth-resolved models of advection-dominated environmental systems with biogeochemical reactions and offers advantages in performance over other numerical integration schemes that often require considerable computational resources.

Summary
Here, LBNL scientists present a numerical integration method for solving systems of partial differential equations (PDEs) that arise in modeling environmental processes undergoing advection and biogeochemical reactions. The salient feature of these PDEs is that all partial derivatives appear in linear expressions. As a result, the system can be viewed as a set of ordinary differential equations (ODEs), albeit each one along a different characteristic. The proposed method, termed the method of alternating characteristics (MAC), then consists of alternating between equations and integrating each one step-wise along its own characteristic, thus creating a customized grid on which solutions are computed. Since the solutions of such PDEs are generally smoother along their characteristics, the method offers the potential of using larger time steps while maintaining accuracy and reducing numerical dispersion. The advantages in efficiency and accuracy of the proposed method are demonstrated in two illustrative examples that simulate depth-resolved reactive transport and soil carbon cycling.

Contacts (BER PM)
Daniel Stover
Terrestrial Ecosystem Science, SC-23.1
Daniel.Stover@science.doe.gov (301-903-0289)

(PI Contact)
William J. Riley
Lawrence Berkeley National Laboratory
wjriley@lbl.gov; 510-495-2223

Funding
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Terrestrial Ecosystem Science Program, under contract number DE-AC02-05CH11231. K.G. acknowledges support from the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by ORAU under contract number DE-SC0014664.

Publications
Georgiou, K., J. Harte, A. Mesbah, and W. J. Riley. "A method of alternating characteristics with application to advection-dominated environmental systems." Computational Geosciences, (2018). [DOI:10.1007/s10596-018-9729-5]

Topic Areas:

  • Research Area: Earth and Environmental Systems Modeling
  • Research Area: Terrestrial Ecosystem Science

Division: SC-23.1 Climate and Environmental Sciences Division, BER

 

BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Aug 24, 2019
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]

Aug 08, 2019
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]

Aug 05, 2019
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]

Jul 29, 2019
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]

Jul 15, 2019
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]

List all highlights (possible long download time)