Our paper on “Does GOSAT capture the true seasonal cycle of carbon dioxide?” has been published at ACP (Atmospheric Chemistry and Physics)! In the paper, we study the average seasonal variability of satellite-retrieved carbon dioxide concentrations. This variability mostly comes from plant photosynthesis — in that sense, we poetically measure the breathing of our planet from space.
We compared 5 years of satellite measurements from the Greenhouse Gases Observing Satellite (GOSAT) to ground-based measurements at the TCCON sites, other retrieval algorithms, and inverse models that assimilate in situ measurements. This is the first time when the accuracy of satellite-retrieved CO2 seasonal cycle is thoroughly evaluated.
- GOSAT seasonal cycle amplitude is generally accurate to within 1 ppm.
- GOSAT maximum XCO2 is 2–3 weeks delayed from TCCON but minimum is accurately captured.
- We found surprisingly that the differences between modelled seasonal cycles can be larger than GOSAT-to-model differences.