Empirical upscaling of OzFlux eddy covariance for high-resolution monitoring of terrestrial carbon uptake in Australia
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Published:2023-10-09
Issue:19
Volume:20
Page:4109-4134
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ISSN:1726-4189
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Container-title:Biogeosciences
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language:en
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Short-container-title:Biogeosciences
Author:
Burton Chad A.ORCID, Renzullo Luigi J., Rifai Sami W.ORCID, Van Dijk Albert I. J. M.ORCID
Abstract
Abstract. We develop high-resolution (1 km) estimates of gross primary
productivity (GPP), ecosystem respiration (ER), and net ecosystem exchange
(NEE) over the Australian continent for the period January 2003 to June 2022
by empirical upscaling of flux tower measurements. We compare our estimates
with nine other products that cover the three broad categories that define
current methods for estimating the terrestrial carbon cycle and assess if
consiliences between datasets can point to the correct dynamics of
Australia's carbon cycle. Our results indicate that regional empirical
upscaling greatly improves upon the existing global empirical upscaling
efforts, outperforms process-based models, and agrees much better with the
dynamics of CO2 flux over Australia as estimated by two regional
atmospheric inversions. Our nearly 20-year estimates of terrestrial carbon
fluxes revealed that Australia is a strong net carbon sink of −0.44 PgC yr−1 (interquartile range, IQR = 0.42 PgC yr−1) on average, with an inter-annual variability of
0.18 PgC yr−1 and
an average seasonal amplitude of 0.85 PgC yr−1. Annual mean carbon uptake
estimated from other methods ranged considerably, while carbon flux
anomalies showed much better agreement between methods. NEE anomalies were
predominately driven by cumulative rainfall deficits and surpluses,
resulting in larger anomalous responses from GPP than ER. In contrast, we
show that the long-term average seasonal cycle is dictated more by the
variability in ER than GPP, resulting in peak carbon uptake typically
occurring during the cooler, drier austral autumn and winter months. This
new estimate of Australia's terrestrial carbon cycle provides a benchmark
for assessment against land surface model simulations and a means for
monitoring of Australia's terrestrial carbon cycle at an unprecedented
high resolution. We call this new estimate of Australia's terrestrial carbon
cycle “AusEFlux” (Australian Empirical Fluxes).
Funder
Australian Government
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Ecology, Evolution, Behavior and Systematics
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