On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

<p>Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric <span class="inline-formula">CO<sub>2</sub></span>. Quantifying the impact of climate anomalies on the net ecosyst...

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Bibliographic Details
Main Authors: B. Byrne, D. B. A. Jones, K. Strong, S. M. Polavarapu, A. B. Harper, D. F. Baker, S. Maksyutov
Format: Article
Language:English
Published: Copernicus Publications 2019-10-01
Series:Atmospheric Chemistry and Physics
Online Access:https://www.atmos-chem-phys.net/19/13017/2019/acp-19-13017-2019.pdf
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Summary:<p>Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric <span class="inline-formula">CO<sub>2</sub></span>. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric <span class="inline-formula">CO<sub>2</sub></span> observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem adjoint model to assimilate GOSAT observations. Monthly NEE anomalies are compared to “proxies”, variables that are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Statistically significant correlations (<span class="inline-formula"><i>P</i>&lt;0.05</span>) are obtained between posterior NEE anomalies and anomalies in soil temperature and FLUXCOM NEE on continental and larger scales in the tropics, as well as in the northern extratropics on subcontinental scales during the summer (<span class="inline-formula"><i>R</i><sup>2</sup>≥0.49</span>), suggesting that GOSAT measurements provide a constraint on NEE interannual variability (IAV) on these spatial scales. Furthermore, we show that GOSAT flux inversions are generally better correlated with the environmental proxies and FLUXCOM NEE than NEE anomalies produced by a set of terrestrial biosphere models (TBMs), suggesting that GOSAT flux inversions could be used to evaluate TBM NEE fluxes.</p>
ISSN:1680-7316
1680-7324