Aircraft measurements of carbon dioxide and methane for the calibration of ground-based high-resolution Fourier Transform Spectrometers and a comparison to GOSAT data measured over Tsukuba and Moshiri

Abstract

Abstract. Aircraft measurements of carbon dioxide and methane over Tsukuba (36.05 • N, 140.12 • E) (February 2010) and Moshiri (44.36 • N, 142.26 • E) (August 2009) were made to calibrate ground-based high-resolution Fourier Transform Spectrometers (g-b FTSs) and to compare with the Greenhouse gases Observing SATellite (GOSAT). The aircraft measurements over Tsukuba in February 2010 were successful in synchronizing with both the g-b FTS and GOSAT for the first time. Airborne in situ and flask-sampling instruments were mounted on the aircraft, and measurements were carried out between altitudes of 0.5 and 7 km to obtain vertical profiles of carbon dioxide (CO 2 ), methane (CH 4 ), and other gaseous species.By comparing the g-b FTS measurements with the airborne measurements, the column-averaged dry air mole fractions of CO 2 (X CO 2 ) and CH 4 (X CH 4 ) retrieved from the g-b FTS measurements at Tsukuba were biased low by 0.33 ± 0.11 % for X CO 2 and 0.69 ± 0.29 % for X CH 4 .The g-b FTS values at Moshiri were biased low by 1.24 % for X CO 2 and 2.11 % for X CH 4 . The GOSAT data show biases that are 3.1 % ± 1.7 % lower for X CO 2 and 2.5 % ± 0.8 % lower for X CH 4 than the aircraft measurements obtained over Tsukuba.

Intercomparison of open-path trace gas measurements with two dual-frequency-comb spectrometers

“…These widths decrease to 1.5 ppm, 12 ppb, 66 ppm, and 0.17 ppm, respectively, for 5 min averaging times. These mean values correspond to a relative offset of 0.14 % CO 2 , −0.35 % CH 4 , and 0.4 % H 2 O and are close to the WMO compatibility standards of 0.1 ppm for CO 2 and 2 ppb for CH 4 (Tans and Zellweger, 2015). We emphasize the agreement here is achieved over a 2-week period despite outdoor temperature variations of 4.6 to 28.9 • C, DCS instrument ambient temperature variations from 17 to 25 • C, 10 to 90 % relative humidity fluctuations, and large turbulence-induced return power fluctuations.…”

“…3.2. This basic discrepancy between retrievals based on line shape parameters from a spectral database and manometric and gravimetric calibrations (WMO standard) is not unique to DCS. Several studies have calibrated the Total Carbon Column Observing Network (TCCON) retrievals against WMO-based instruments (Wunch et al, 2010;Messerschmidt et al, 2011;Geibel et al, 2012;Tanaka et al, 2012). Although TCCON is not a solely HITRAN-based analysis , a correction factor of 0.9898 for CO 2 , 0.9765 for CH 4 , and 1.0183 for H 2 O (Wunch et al, 2010) is needed to bring the overall TCCON retrievals into agreement with the WMO-based data.…”

Bias corrections of GOSAT SWIR XCO<sub>2</sub> and XCH<sub>4</sub> with TCCON data and their evaluation using aircraft measurement data

“…In order to test for remaining biases in the GOSAT data after applying the empirical correction developed using TCCON data, we use aircraft profile data provided by the Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) project (Machida et al, 2008), the NOAA Earth System Research Laboratory/Global Monitoring Division (ESRL/GMD; Xiong et al, 2008;Sweeney et al, 2015), the US Department of Energy (DOE; Biraud et al, 2013;Schmid et al, 2014), the National Institute for Environmental Studies (NIES; Machida et al, 2001), the Japan Meteorological Agency (JMA; Tsuboi et al, 2013), the HI-APER Pole-to-Pole Observations (HIPPO) project (Wofsy et al, 2011Kort et al, 2012;Santoni et al, 2014), and an aircraft measurement campaign by NIES and the Japan Aerospace Exploration Agency (JAXA) (Tanaka et al, 2012). To calculate aircraft-based XCO 2 and XCH 4 (as described in the next paragraph), we also used tower data from the Meteorological Research Institute (MRI) in Tsukuba (Inoue andMatsueda, 1996, 2001) and the NOAA ESRL/GMD tall tower network in Park Falls, WI and West Branch, IA .…”

Validation of TANSO-FTS/GOSAT XCO<sub>2</sub> and XCH<sub>4</sub> glint mode retrievals using TCCON data from near-ocean sites

“…GGG includes its own Fourier transformation algorithm to derive the spectra from the recorded interferograms: it also corrects for the solar intensity variations during the recording of the interferogram due to the occurrence of clouds or heavy aerosol loads . Most TCCON stations have been calibrated to WMO standards by comparison to aircraft in situ overpass measurements, and global calibration factors for each gas (0.9898 ± 0.001(1σ ) for XCO 2 and 0.9765 ± 0.002(1σ ) for XCH 4 ) are applied to the TC-CON data Messerschmidt et al, 2011;Tanaka et al, 2012;Geibel et al, 2012). To ensure networkwide consistency, Messerschmidt et al (2010) and discovered and minimized laser sampling errors.…”

“…Although all the GOSAT greenhouse gases retrieval algorithms have already been validated, to some degree, via the TCCON observations (e.g. Wunch et al, 2011b;Tanaka et al, 2012;Yoshida et al, 2013;Dils et al, 2014), only the land data have been selected in these previous studies. Inoue et al (2013Inoue et al ( , 2014 made ocean data of NIES SWIR L2 products validation by aircraft measurements.…”