Quantifying Cold Season Soil CO2 Emissions in Alaska and Northwest Canada
Abstract
As temperatures increase across the Arctic, particularly during the cold seasons, soil carbon may be increasingly vulnerable to microbial mineralization and transfer to the atmosphere as CO2. Loss of CO2 from soils during shoulder (autumn/spring) and winter seasons could greatly alter the annual net ecosystem carbon balance, yet the magnitude of these emissions is not well understood. This study incorporates new information gained from a NASA Arctic Boreal Vulnerability Experiment (ABoVE) network of CO2 soil respiration sensors using Forced Diffusion (FD) flux chambers and eddy covariance tower observations across Alaska and northwestern Canada. These records show that CO2 loss rates can exceed 0.5 gC m-2 d-1 in midwinter and may reach >3 gC m-2 d-1 during the spring and autumn shoulder seasons. Ecosystem rates of loss depend greatly on soil temperature, surface radiation, soil texture and organic substrates, vegetation community type, and landscape moisture characteristics. We extrapolate the FD chamber and tower fluxes to the greater ABoVE domain (5.9x105 km2) to obtain a full non-growing season (October 2016 through April 2017) CO2 flux budget using a generalized additive model (GAM) and information from multi-scale (visible-infrared, microwave) satellite remote sensing and ancillary inputs. We compare the 100-m resolution GAM results with estimates obtained from ecosystem models including the Community Land Model (CLM), the Lund-Potsdam-Jena Wald Schnee und Landschaft version (LPJ-wsl) and the Terrestrial Carbon Flux (TCF) model. These results indicate non-growing season soil emissions of > 180 TgC for the study domain. The considerable spatial variability observed in the regional flux estimates illustrates the importance of finer resolution flux monitoring and modeling efforts.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B31F2561W
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCESDE: 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCESDE: 1640 Remote sensing;
- GLOBAL CHANGE