Path-averaged atmospheric CO2 measurement using a 1.57 μm active remote sensor compared with multi-positioned in situ sensors

The Green-house gas Observation SATellite (GOSAT) was launched to determine the continental CO 2 inventories. Its sensor is based on a passive remote sensing technique developed to achieve less than 1% relative accuracy for atmospheric CO 2 measurements. Meanwhile, a laser remote sensor with the differential absorption spectrometry has been developed for a candidate of a future space-based mission to observe the atmospheric CO 2 or other trace gases. A prototype of the newly developed active remote sensor has been performed to demonstrate a properly validated performance for ground-based and airborne systems. This study shows the results of the in-house and field measurements. The in-house measurement demonstrated the linearity with the correlation coefficient of over 0.99 between the instrumental response and the known CO 2 density in the cell. The diurnal variation obtained from our system is consistent (correlation coefficient of 0.95) with that of multi-positioned in situ sensors, indicates the spatial responsibility of the atmospheric CO2 obtained from our remote sensor with two ~3-km observation paths.