Abstract
Climate change is of increasing concern and efforts to mitigate its effects are targeted on reducing fossil CO2 emissions. Satellite observations play a key role in the understanding and management of the problem. Whilst detecting CO2 optically is relatively straight-forward, and has been achieved with small satellites, accurate quantitative mapping of CO2 requires very high precision (<1%) measurements of gas concentration. This is usually achieved through identifying CO2 by its spectral absorption bands at 1.56-1.62μm and 1.92-2.06μm wavelength by using high resolution spectrometers (e.g. 0.27cm-1 resolution at a signal-to-noise ratio (SNR) of >300:1). This normally requires high performance, large and complex instruments whose high cost, mass, volume, and power requirements preclude their use on small satellites. This paper presents the developmental stage of a single channel (1.6 μm) compact precision Spatial Heterodyne Atmospheric Carbon-Dioxide Spectrometer (SHACS), which utilises the Spatial Heterodyne Spectrometer (SHS) technique to form a robust, compact, no-moving-part Fourier Transform Spectrometer (FTS). This instrument achieves a high spectral resolution of 0.25cm-1 at a high SNR of >700:1 and can fit into a micro-satellite platform. With this performance, high quality measurements of atmospheric CO2 concentration with measurement precision of <4 ppm can be achieved.