Wavelength optimization of space-borne electro-optic dual-comb lidar for CO2 detection at 1572 nm

The space-borne Integrated Path Differential Absorption (IPDA) lidar can measure the global distribution of CO2. Here, we simulate measurements on the R16 absorption line employing a 1572 nm electro-optic dual-comb interferometer. We introduce a comprehensive modeling and retrieval framework to assess the lidar's capability in measuring the column-averaged of CO2 in the atmosphere. The assessment combines data simulation with linearization error analysis to solve the nonlinearity in retrieval. Our findings suggest that positioning any sampling wavelength at the absorption peak will significantly increase the random error by about 30%. The lidar can operate with an optimal wavelength strategy where the wavelength bias has virtually no effect, but it must still account for the effects of atmospheric temperature and pressure. We performed a comprehensive global evaluation using geophysical data, comparing results across 3 to 17 wavelengths. Distributing 20 W launched power over 11 wavelengths enables measurement with an error below 0.9 ppm over most of the Earth's surface.