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Abstract
The UK is one of several countries around the
world that has enacted legislation to reduce its greenhouse gas
emissions. In this study, we present top-down emissions of methane (CH4) and nitrous oxide (N2O)
for the UK and Ireland over the period August~2012 to August~2014.
These emissions were inferred using measurements from a network of four
sites around the two countries. We used a hierarchical Bayesian inverse
framework to infer fluxes as well as a set of covariance parameters that
describe uncertainties in the system. We inferred average UK total
emissions of 2.09 (1.65–2.67) Tg yr−1 CH4 and 0.101 (0.068–0.150) Tg yr−1 N2O
and found our derived UK estimates to be generally lower than the a
priori emissions, which consisted primarily of anthropogenic sources and
with a smaller contribution from natural sources. We used sectoral
distributions from the UK National Atmospheric Emissions Inventory
(NAEI) to determine whether these discrepancies can be attributed to
specific source sectors. Because of the distinct distributions of the
two dominant CH4 emissions sectors in the UK, agriculture and waste, we found that the inventory may be overestimated in agricultural CH4 emissions. We found that annual mean N2O
emissions were consistent with both the prior and the anthropogenic
inventory but we derived a significant seasonal cycle in emissions. This
seasonality is likely due to seasonality in fertilizer application and
in environmental drivers such as temperature and rainfall, which are not
reflected in the annual resolution inventory. Through the hierarchical
Bayesian inverse framework, we quantified uncertainty covariance
parameters and emphasized their importance for high-resolution emissions
estimation. We inferred average model errors of approximately 20 and
0.4 ppb and correlation timescales of 1.0 (0.72–1.43) and 2.6 (1.9–3.9)
days for CH4 and N2O, respectively. These errors
are a combination of transport model errors as well as errors due to
unresolved emissions processes in the inventory. We found the largest CH4
errors at the Tacolneston station in eastern England, which may be due
to sporadic emissions from landfills and offshore gas in the North Sea.
Original language | English |
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Pages (from-to) | 6393-6406 |
Number of pages | 14 |
Journal | Atmospheric Chemistry and Physics |
Volume | 15 |
Issue number | 11 |
Early online date | 11 Jun 2015 |
DOIs | |
Publication status | Published - Jun 2015 |
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Dive into the research topics of 'Quantifying methane and nitrous oxide emissions from the UK and Ireland using a national-scale monitoring network'. Together they form a unique fingerprint.Projects
- 1 Finished
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GAUGE: Greenhouse Gas UK & Global Emissions (GUAGE)
Palmer, P. (Principal Investigator), Rigby, M. L. (Researcher), Stavert, A. R. (Researcher), Wenger, A. (Researcher), Young, T. D. S. (Researcher) & O'Doherty, S. (Principal Investigator)
30/06/13 → 29/09/17
Project: Research