Abstract
The issue of climate change is of ever-increasing concern to the global community and key to understanding the problem is the characterization of sources, sinks and transportation of greenhouse gases (GHGs) such as atmospheric carbondioxide (CO2). This requires space-based observations to provide a truly global picture, due to the sparse nature of terrestrial monitoring sites. The sparseness of these sites, especially along the tropics makes it difficult to determine the extent of carbon fluxes around the equatorial regions. To fully characterize the problem, a high spatial and temporal resolution is needed. Although atmospheric CO2 can be detected optically by small satellites, precise quantitative mapping requires extremely high precision (0.3% to 0.5%) measurements of gas concentrations at spectral absorption
bands of 1.56-1.62μm and 1.92-2.06μm wavelengths, using high resolution spectrometers (e.g. 0.27 cm-1 resolution at a signal-to-noise ratio (SNR) of >300:1). This normally requires high-performance, large and complex instruments, carried by single, large and expensive satellites. No single satellite can provide high temporal resolution. Therefore, a constellation of satellites is needed to resolve the underestimation of CO2 uptake (sink) by the terrestrial biosphere. In this paper, we present the developmental progress of SHACS - a low-cost, compact, precision, robust, no-moving part spatial heterodyne atmospheric carbon-dioxide spectrometer, and also present some results of the Total Column Carbondioxide (TCCO2) measurements obtained at Surrey in June 2019. The SHACS instrument has achieved a high measurement precision of <0.3% and a high spectral resolution of 0.22 cm−1 at a high SNR of >900:1.