A global wetland CH4 dataset and process-based uncertainty structure for atmospheric CH4 inverse modeling applications.
Abstract
Wetland methane (CH4) fluxes remain a principal source of uncertainty in the global atmospheric CH4 budget, largely due to poorly constrained process controls on CH4 production in wetland soils. Process-based estimates of global wetland CH4 emissions and their associated uncertainties can provide crucial prior information for model-based top-down CH4 emission estimates. Here we construct a multi-model wetland CH4 emission inventory for use in atmospheric chemical transport models. Our model ensemble is based on satellite-derived surface water extent and precipitation re-analyses, nine carbon cycle models respiration rates and three temperature parameterizations for the period 2009-2010; an extended ensemble subset - based solely on precipitation and a single carbon model - is derived for the period 2001-2015. Atmospheric chemical transport model (GEOS-Chem) with our ensemble emissions performs favourably against in-situ CH4 measurements, compared to GEOS-Chem simulations driven with published wetland CH4 emissions scenarios. We find that uncertainties in carbon decomposition and wetland extent account are the primary sources of uncertainty in mean tropical and sub-tropical wetland CH4 fluxes. In wetlands north of 50°N, temperature parameterizations of CH4 production are the primary uncertainty for mean fluxes, while carbon decomposition is a major source of uncertainty in the timing of emissions. We constrain our a priori ensemble by conducting dedicated inverse estimates of wetland CH4 fluxes using a global atmospheric CH4 inversion framework, constrained by satellite datasets. We use a posteriori CH4 fluxes - and associated uncertainty - as a means for weighing global wetland CH4 emission biogeochemical process hypotheses.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMGC21C1115B
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 1631 Land/atmosphere interactions;
- GLOBAL CHANGEDE: 1694 Instruments and techniques;
- GLOBAL CHANGE