NGEE Arctic
Next-Generation Ecosystem Experiments
Advancing the predictive power of Earth system models through understanding
of the structure and function of Arctic terrestrial ecosystems
Microtopography Determines How CO2 and CH4 Exchanges Respond to Temperature and Precipitation in Polygonal Tundra
Microtopography Determines How CO2 and CH4 Exchanges Respond to Temperature and Precipitation in Polygonal Tundra
December 21st, 2017
Microtopographic variation among troughs, rims, and centers strongly affects the movement of surface water and snow and thereby affects soil water contents and active layer development.
The Objective:
- Quantified and scaled the effects of microtopography on biogeochemistry, hydrology, and plant processes—and thereby CO2 and CH4 exchanges with the atmosphere—using observations and three-dimensional modeling.
New Science:
- Polygon microtopography affects CO2 and CH4 emissions, but landscape scaling of polygon types accurately represents landscape 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.
The Impact:
- Demonstrated excellent agreement between modeled and observed CH4 and CO2 fluxes (Figure) and the relevant biogeochemical, hydrological, and thermal controlling processes.
- Results imply needed improvements to the DOE E3SM land model (ELMv1-ECA), which we are pursuing.
Ecosys accurately represented eddy covariance measured surface (b) CO2 and (c) CH4 emissions when scaled from individual polygons to the landscape.