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

摘要

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 calibrateground-based high-resolution Fourier Transform Spectrometers (g-b FTSs) andto compare with the Greenhouse gases Observing SATellite (GOSAT). Theaircraft measurements over Tsukuba in February 2010 were successful insynchronizing with both the g-b FTS and GOSAT for the first time. Airborne in situ and flask-sampling instruments were mounted on the aircraft, andmeasurements were carried out between altitudes of 0.5 and 7 km to obtainvertical profiles of carbon dioxide (CO₂), methane (CH₄), and othergaseous species.By comparing the g-b FTS measurements with the airborne measurements, thecolumn-averaged dry air mole fractions of CO₂ (X_CO2)and CH₄ (X_CH4) retrieved from the g-b FTS measurementsat Tsukuba were biased low by 0.33 ± 0.11% for X_CO2 and 0.69 ± 0.29% for X_CH4.The g-b FTS values at Moshiri were biased low by 1.24% forX_CO2 and 2.11% for X_CH4. The GOSAT datashow biases that are 3.1% ± 1.7% lower for X_CO2 and 2.5% ± 0.8% lower for X_CH4 than the aircraftmeasurements obtained over Tsukuba.