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Observation of the Earth’s environment from space is important for resolving issues resulting from global climate change. Increasing anthropogenic carbon dioxide (CO2) and methane are species to climate change. To estimate accurately sinks and sources of CO2 in the biosphere, measurement uncertainties of the column averaged dry air mole fraction of CO2 (XCO2) are expected to be 1-3 ppm (0.3%-1%)[1]. The Greenhouse Gases Observing Satellite (GOSAT) and the Orbiting Carbon Observatory (OCO-2) have proceeded to reveal the global carbon exchange [2, 3]. The GOSAT sensor observes trace gases using a passive remote sensing technique. However, passive techniques using solar light limits observation because 1) the total column CO2 can only be evaluated only during the daytime, 2) solar seasonal dependence reduces global coverage, such as the northern hemisphere in winter, 3) unknowns and variations in broken clouds and aerosol contamination also cause bias errors. To resolve these issues, active remote sensors, such as a differential absorption lidar (DIAL) or a laser absorption spectrometer (LAS), are valuable tools for future trace gas sensing from space as they involve no seasonal dependence, can mitigate the impact of broken clouds and aerosol, and can evaluate XCO2 all day. According to earlier studies [4-8], a precision of up to 0.7 percent has already been achieved. This study aims at demonstrating a sensitivity analysis for a space-borne system and the results of the airborne test to evaluate column-averaged CO2.
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