Microtopography in polygonal tundra affects CO2 and CH4 emissions, but landscape scaling of polygon types accurately represents landscape-scale gas exchanges with the atmosphere.
Scientists from Lawrence Berkeley National Laboratory applied a well-tested three-dimensional land model (ecosys) to the NGEE-Arctic Barrow, Alaska polygonal tundra sites to quantify and scale the effects of microtopography on biogeochemistry, hydrology, and plant processes and thereby CO2 and CH4 exchanges with the atmosphere. Much of the spatial and temporal variations in CO2 and CH4 fluxes were driven from topographic effects on water and snow movement. Although small-scale elevation variation causes large spatial variations, their results demonstrated that representing individual polygon type dynamics allowed for accurate predictions of landscape-scale states and gas exchanges with the atmosphere.
They demonstrated excellent agreement between model predictions and NGEE-Arctic observations of CH4 and CO2 fluxes and the relevant biogeochemical, hydrological, and thermal controlling processes. Interestingly, the net primary productivity in higher features and CH4 emissions across the landscape increased from 1981 to 2015 were attributed more to precipitation than temperatures increases. Their results highlight needed improvements to the DOE E3SM land model (ELMv1-ECA), which they are actively pursuing.
Current ESM land model representations of high-latitude biogeochemistry and plant processes in spatially heterogeneous landscapes ignore several important processes and representation. They found a strong control of water and snow movement on biogeochemical dynamics and net primary production that varied by landscape position. The landscape-scale dynamics were also well captured by scaling the various polygon type dynamics. The analysis here demonstrates a viable approach to representing fine-scale processes and links to landscape scales. Together their findings challenge widely held assumptions about controls on landscape-scale energy and water budgets, and are motivating our ongoing improvements to the DOE land model (ELMv1-ECA).
BER PM Contacts
William J. Riley
Lawrence Berkeley National Laboratory
This research was supported by the Director, Office of Science, Office of Biological and Environmental Research of the US Department of Energy under Contract No. DE-AC02-05CH11231 as part of the Next-Generation Ecosystem Experiments (NGEE Arctic) project.
Grant, R.F., Z.A. Mekonnen, W.J. Riley, B. Arora, and M.S. Torn. “Mathematical Modelling of Arctic Polygonal Tundra with Ecosys: 2. Microtopography Determines How CO2 and CH4 Exchange Responds to Changes in Temperature and Precipitation.” JGR-Biogeosciences, 122 (12), 3174-3187 (2017). [DOI: 10.1002/2017JG004037]
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
May 10, 2019
Quantifying Decision Uncertainty in Water Management via a Coupled Agent-Based Model
Considering risk perception can improve the representation of human decision-making processes in age [more...]
May 09, 2019
Projecting Global Urban Area Growth Through 2100 Based on Historical Time Series Data and Future Scenarios
Study provides country-specific urban area growth models and the first dataset on country-level urba [more...]
May 05, 2019
Calibrating Building Energy Demand Models to Refine Long-Term Energy Planning
A new, flexible calibration approach improved model accuracy in capturing year-to-year changes in bu [more...]
May 03, 2019
Calibration and Uncertainty Analysis of Demeter for Better Downscaling of Global Land Use and Land Cover Projections
Researchers improved the Demeter model’s performance by calibrating key parameters and establi [more...]
Apr 22, 2019
Representation of U.S. Warm Temperature Extremes in Global Climate Model Ensembles
Representation of warm temperature events varies considerably among global climate models, which has [more...]
List all highlights (possible long download time)