Spatial heterodyne spectroscopy for space-based measurements of atmospheric CO₂

To reduce the error from measurement and retrieval process, a new technology of spatial heterodyne spectroscopy is proposed. The principle of this technology and the instrument spatial heterodyne spectrometer (SHS) are introduced. The first application of this technology will be for CO₂ measurements from space on a high spectral observation satellite. The outstanding measurement principle and the priority of combination of retrieval algorithm and three channels (O₂ A-band, CO₂ 1.58. μ m and 2.06. μ m bands) are theoretically analyzed and numerically simulated. Experiments using SHS prototype with low spectral resolution of 0.4.cm^-1 are carried out for preliminary validation. The measurements show clear CO₂ absorption lines and follow the expected signature with theory spectrum, and the retrievals agreed well with GOSAT CO₂ products, except a small bias of about 4×10^-6. The results show that the ability of spatial heterodyne spectroscopy for CO₂ detecting is obvious, and SHS is a competent sensor.