Retrieval algorithm for CO<sub>2</sub> and CH<sub>4</sub> column abundances from short-wavelength infrared spectral observations by the Greenhouse gases observing satellite

Abstract

Abstract. The Greenhouse gases Observing SATellite (GOSAT) was launched on 23 January 2009 to monitor the global distributions of carbon dioxide and methane from space. It has operated continuously since then. Here, we describe a retrieval algorithm for column abundances of these gases from the short-wavelength infrared spectra obtained by the Thermal And Near infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS). The algorithm consists of three steps. First, cloud-free observational scenes are selected by several cloud-detection methods. Then, column abundances of carbon dioxide and methane are retrieved based on the optimal estimation method. Finally, the retrieval quality is examined to exclude low-quality and/or aerosol-contaminated results. Most of the retrieval random errors come from instrumental noise. The interferences due to auxiliary parameters retrieved simultaneously with gas abundances are small. The evaluated precisions of the retrieved column abundances for single observations are less than 1% in most cases. The interhemispherical differences and temporal variation patterns of the retrieved column abundances show features similar to those of an atmospheric transport model.

Simulated retrievals for the remote sensing of CO<sub>2</sub>, CH<sub>4</sub>, CO, and H<sub>2</sub>O from geostationary orbit

“…The Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instrument was operational for measurements of atmospheric compositions from 2002 to 2012, with CO 2 , CH 4 , CO, and H 2 O as four of its target species (Buchwitz et al, 2004(Buchwitz et al, , 2007Schrijver et al, 2009;Schneising et al, 2011). The Greenhouse gases Observing SATellite (GOSAT), developed by the Japan Aerospace Exploration Agency and launched in January 2009, is the world's first mission dedicated to the monitoring of CO 2 and CH 4 (Yokota et al, 2009;Butz et al, 2011;Yoshida et al, 2011). In addition, the Orbiting Carbon Observatory (OCO)-2 mission, successfully launched in July 2014, now provides high-quality and worldwide column abundances of CO 2 (Crisp et al, 2004(Crisp et al, , 2012.…”

“…This method for retrieval has been widely used for GOSAT (Yoshida et al, 2011), Tropospheric Emission Spectrometer, and OCO-2 (Kuang et al, 2002;Connor et al, 2008;O'Dell et al, 2012;Crisp et al, 2012). The state vector x, model parameters b, and error e are related to the measurement vector y by a forward model F:…”

Improvement of Cloud-data Filtering Method Using Spectrum of AERI

“…특히 Aqua/ AIRS (Aumann et al, 2003;Divakarla et al, 2006), MetOp-A/IASI (Clerbaux et al, 2009;George et al, 2009;Liu et al, 2009), GOSAT (Yoshida et al, 2011;Yokota et al, 2009), MOPPIT (Pan et al, 1998 (Kang et al, 2013)하였다 (Fig. 1).…”

EOF-based regression algorithm for the fast retrieval of atmospheric CO2 total column amount from the GOSAT observations

“…TCCON XCO 2 measurements taken within ± 1h of the GOSAT overpass time were chosen as the "known" value for the GOSAT observation if the footprint of the observation was located within a 5° latitude-longitude circle around CAI-screened data set [17]. These observations were non-uniformly distributed among …”

“…These regions include For the construction of the "measured signal" R , we used the scalar spectral radiance S that was generated by NIES operational algorithm for CO 2 retrievals [17]. This scalar radiance was computed from P-and S-signal polarizations provided by the Japan Aerospace Exploration Agency (JAXA) within the L1B product [18].…”