Usability of optical spectrum analyzer in measuring atmospheric CO 2 and CH 4 column densities: inspection with FTS and aircraft profiles in situ
The practical usefulness of a desktop optical spectrum analyzer (OSA) for measuring atmospheric CO 2 and CH 4 column densities at surface sites was examined in two separate measurement campaigns. The first comparison involved operating the OSA in parallel with a high resolution Fourier transform spectroscopy (FTS) situated at the University of Wollongong in Australia. Scale factors for the OSA were assigned for the column average volume mixing ratios of xCO 2 and xCH 4 by comparing with the well-studied FTS. The second method is a calibration against aircraft CO 2 profiles in situ over Tsukuba in Japan obtained during a GOSAT validation campaign carried out from 28 January to 7 February 2011. The xCO 2 values in the campaign, deduced by use of a derived OSA scale factor, were in excellent agreement with the integrated aircraft profiles.