NanoCarb part 2: Performance assessment for total column CO2 monitoring from a nano-satellite

NanoCarb is an innovative Fourier Transform imaging spectrometer dedicated to the measurement of CO2 and CH4. Both its unusual optical principle and sampling strategy allows to reach a compact design, ideal for small satellite constellation as investigated by the European project SCARBO. The NanoCarb performance assessment as well as a proof of concept are required in this framework. A strategy of design is developed to optimize the performances and reach the sensitivity target of the space mission, demonstrating the potential of the concept without drastic complexity gain. A preliminary bias mitigation in the retrieval strategy is presented concerning water for CO2 measurement, illustrating the efficiency and the flexibility of the NanoCarb partial interferogram sampling technic. The presented design reaches a random error sub-ppm for CO2 and sub-10ppb for CH4, considering a 128 to 192 km swath, respectively, for 2 or 3 km of resolution at ground. A full mitigation of the water bias is performed on CO2 band thanks to partial interferograms.