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XCO2 in an emission hot-spot region: the COCCON Paris campaign 2015.

Authors :
Vogel, Felix R.
Frey, Matthias
Staufer, Johannes
Hase, Frank
Broquet, Gregoire
Xueref-Remy, Irene
Chevallier, Frederic
Ciais, Philippe
Sha, Mahesh Kumar
Chelin, Pascale
Jeseck, Pascal
Janssen, Christof
Yao-Veng Te
Groß, Jochen
Blumenstock, Thomas
Qiansi Tu
Orphal, Johannes
Source :
Atmospheric Chemistry & Physics Discussions; 2018, p1-37, 37p
Publication Year :
2018

Abstract

Abstract. Providing timely information on urban Greenhouse-Gas (GHG) emissions and their trends to stakeholders relies on reliable measurements of atmospheric concentrations and the understanding of how local emissions and atmospheric transport influence these observations. Portable Fourier Transform Infra-Red (FTIR) spectrometers were deployed at 5 stations in the Paris metropolitan area to provide column-averaged concentrations of CO<subscript>2</subscript> (XCO<subscript>2</subscript>) during a field campaign in spring of 2015. Here, we describe and analyze the variations of XCO<subscript>2</subscript> observed at different sites and how they changed over time. We find that observations upwind and downwind of the city centre differ significantly in their XCO<subscript>2</subscript> concentrations, while the overall variability of the daily cycle is similar, i.e., increasing during night-time with a strong decrease (typically 2–3ppm) during the afternoon. An atmospheric transport model framework (CHIMERE-CAMS) was used to simulate XCO<subscript>2</subscript> and predict the same behaviour seen in the observations, which supports key findings, e.g. that even in a densely populated region like Paris (over 12 Million people), biospheric uptake of CO<subscript>2</subscript> can be of major influence on daily XCO<subscript>2</subscript> variations. Despite a general offset between modelled and observed XCO<subscript>2</subscript>, the model correctly predicts the impact of the meteorological parameters (e.g. wind direction and speed) on the concentration gradients between different stations. Looking at the local gradients of XCO<subscript>2</subscript> for upwind and downwind station pairs, which is less sensitive to changes in XCO<subscript>2</subscript> regional background conditions, we find the model-data agreement significantly better. Our modelling framework indicates that the local XCO<subscript>2</subscript> gradient between the stations is dominated by the fossil fuel CO<subscript>2</subscript> signal of the Paris metropolitan area. This highlights the usefulness of XCO<subscript>2</subscript> observations to help optimise future urban GHG emission estimates. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
16807367
Database :
Complementary Index
Journal :
Atmospheric Chemistry & Physics Discussions
Publication Type :
Academic Journal
Accession number :
131002564
Full Text :
https://doi.org/10.5194/acp-2018-595