CO2 column-averaged volume mixing ratio derived over Tsukuba from measurements by commercial airlines 1National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
2Meteorological Research Institute, 1-1 Nagamine, Tsukuba 305-0052, Japan
3Japan Aerospace Exploration Agency, Sengen 2-2-1, Tsukuba 305-8505, Japan
*now at: Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
Received: 15 December 2009 – Published in Atmos. Chem. Phys. Discuss.: 09 February 2010 Abstract. Column-averaged volume mixing ratios of carbon dioxide (XCO2) during
the period from January 2007 to May 2008 over Tsukuba, Japan, were derived
using CO2 concentrations measured by Continuous CO2 Measuring
Equipment (CME). The CMEs were installed on Japan Airlines Corporation (JAL)
commercial airliners, which frequently fly to and from Narita Airport. It
was assumed that CO2 profiles over Tsukuba and Narita are the same.
CO2 profile data for 493 flights on clear-sky days were analyzed in
order to calculate XCO2 with one of two ancillary datasets: "Tsukuba
observational" data (rawinsonde and meteorological tower), or "global"
forecast/reanalysis and climatological data (NCEP and CIRA-86). The
amplitude of the seasonal variation of XCO2 using the ancillary data
measured in Tsukuba (XCO2 (Tsukuba observational)) was determined by a
least squares fit using a harmonic function to roughly evaluate the seasonal
variation over Tsukuba. The highest and lowest values of the obtained fitted
curve in 2007 for XCO2 (Tsukuba observational) were 386.4 ± 1.0 and
381.7 ± 1.0 ppm in May and September, respectively, where the errors
represent 1 standard deviation of the fit residuals. The dependence of
XCO2 on the type of ancillary dataset was evaluated. The average
difference between XCO2 from global climatological data,
XCO2 (global), and XCO2 (Tsukuba observational), i.e., the bias of
XCO2 (global) based on XCO2 (Tsukuba observational), was found to be
−0.621 ppm with a standard deviation of 0.682 ppm. The uncertainty of
XCO2 (global) based on XCO2 (Tsukuba observational) was estimated to
be 0.922 ppm. This small uncertainty relative to the GOSAT precision
suggests that calculating XCO2 using data from airliners and global
climatological data can be applied to the validation of GOSAT products for
XCO2 over airports worldwide.
Revised: 04 August 2010 – Accepted: 05 August 2010 – Published: 17 August 2010
Citation: Araki, M., Morino, I., Machida, T., Sawa, Y., Matsueda, H., Ohyama, H., Yokota, T., and Uchino, O.: CO2 column-averaged volume mixing ratio derived over Tsukuba from measurements by commercial airlines, Atmos. Chem. Phys., 10, 7659-7667, doi:10.5194/acp-10-7659-2010, 2010.