GOSAT CO2 and CH4 validation activity with a portable FTS at Pasadena, Chino, and Railroad Valley

The column-average dry air mole fractions of carbon dioxide (XCO2) and methane (XCH4) were measured with a portable Fourier transform spectrometer (FTS), EM27/SUN, using direct sunlight at 1) Caltech, in Pasadena, a northern Los Angeles suburb, 2) Chino, a dairy region east of Los Angeles, and 3) Railroad Valley (RRV), a desert playa in Nevada. They were conducted during the GOSAT/OCO-2 joint campaign for vicarious calibration and validation (cal/val) and its preparatory experiments in June-July 2015. JAXA's GOSAT has been operating since 2009 to monitor the greenhouse gases XCO2 and XCH4 using surface-reflected sunlight from space. GOSAT carries a Fourier Transform Spectrometer (TANSO-FTS) and a Cloud and Aerosol Imager (TANSO-CAI). NASA's OCO-2 has been operating since 2014, carries a grating spectrometer to make precise XCO2 observations with a-few-kilometer resolution. Their polar orbits have 12:46 pm (GOSAT) and 1:30 pm (OCO-2) observing times. For cal/val, these sites were targeted with coincident , near simultaneous ground-based and vertical profiling measurements. These sites are different types of suburban, dairy, and desert areas. Before the campaign, measurements from the JAXA EM27/SUN were compared with those from the Total Carbon Column Observing Network (TCCON) and from the Caltech EM27/SUN at Pasadena. We compared the retrieved values and simultaneously observed diurnal enhancements by advection from the Los Angeles basin. Then, we observed a diurnal cycle at Chino dairy area, an area of concentrated husbandry, producing a CH4 point source. Finally, we conducted the cal/val campaign at RRV coincident with GOSAT and OCO-2 overpass observations. Over RRV, vertical profiles of CO2 and CH4 were measured using the Alpha Jet research aircraft as a part of the NASA Ames Alpha Jet Atmospheric eXperiment (AJAX) . We will compare experimental results from the cal/val campaign for XCO2 and XCH4 with a portable FTS.