1National Institute for Environmental Studies, Tsukuba, Japan
2National Institute of Polar Research, Tokyo, Japan
3Faculty of Mechanics and Mathematics, Tomsk State University, Tomsk, Russia
4Central Aerological Observatory, Dolgoprudny, Russia
5Centre for Atmospheric Chemistry, School of Chemistry, University of Wollongong, Wollongong, NSW, Australia
6Institute of Environmental Physics, University of Bremen, Bremen, Germany
7California Institute of Technology, Pasadena, CA, USA
8Max Planck Institute for Biogeochemistry, Jena, Germany
9Earth Observation Science, University of Leicester, Leicester, UK
10Department of Physics, University of Toronto, Toronto, ON, Canada
11Institute of Physics of the National Academy of Sciences, Minsk, Belarus
12Earth System Observations, Los Alamos National Laboratory, Los Alamos, New Mexico
13Finnish Meteorological Institute, Sodankylä, Finland
14Agencia Estatal de Meteorología (AEMET), CIAI, Santa Cruz de Tenerife, Spain
15Karlsruhe Institute of Technology, IMK-IFU, Garmisch-Partenkirchen, Germany
16Center for Atmospheric and Oceanic Studies, Graduate School of Science, Tohoku University, Sendai, Japan
acurrently at: Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan
Received: 08 Mar 2016 – Discussion started: 04 May 2016
Abstract. The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier transform spectrometers (FTSs) that record near-infrared (NIR) spectra of the sun. From these spectra, accurate and precise observations of CO2 column-averaged dry-air mole fractions (denoted XCO2) are retrieved. TCCON FTS observations have previously been used to validate satellite estimations of XCO2; however, our knowledge of the short-term spatial and temporal variations in XCO2 surrounding the TCCON sites is limited.
Revised: 25 Nov 2016 – Accepted: 01 Dec 2016 – Published: 03 Jan 2017
In this work, we use the National Institute for Environmental Studies (NIES) Eulerian three-dimensional transport model and the FLEXPART (FLEXible PARTicle dispersion model) Lagrangian particle dispersion model (LPDM) to determine the footprints of short-term variations in XCO2 observed by operational, past, future and possible TCCON sites. We propose a footprint-based method for the collocation of satellite and TCCON XCO2 observations and estimate the performance of the method using the NIES model and five GOSAT (Greenhouse Gases Observing Satellite) XCO2 product data sets. Comparison of the proposed approach with a standard geographic method shows a higher number of collocation points and an average bias reduction up to 0.15 ppm for a subset of 16 stations for the period from January 2010 to January 2014. Case studies of the Darwin and Reunion Island sites reveal that when the footprint area is rather curved, non-uniform and significantly different from a geographical rectangular area, the differences between these approaches are more noticeable. This emphasises that the collocation is sensitive to local meteorological conditions and flux distributions.
Belikov, D. A., Maksyutov, S., Ganshin, A., Zhuravlev, R., Deutscher, N. M., Wunch, D., Feist, D. G., Morino, I., Parker, R. J., Strong, K., Yoshida, Y., Bril, A., Oshchepkov, S., Boesch, H., Dubey, M. K., Griffith, D., Hewson, W., Kivi, R., Mendonca, J., Notholt, J., Schneider, M., Sussmann, R., Velazco, V. A., and Aoki, S.: Study of the footprints of short-term variation in XCO2 observed by TCCON sites using NIES and FLEXPART atmospheric transport models, Atmos. Chem. Phys., 17, 143-157, doi:10.5194/acp-17-143-2017, 2017.