A Proof of Concept for Estimating the Annual Atmospheric Carbon Dioxide Variation From Orbiting Carbon Observatory-3 vEarly Data

This work investigates the possibility of estimating the seasonal variation of global carbon dioxide (CO₂) from the data procured by Orbiting Carbon Observatory-3 (OCO-3) during the global lockdown related to the novel coronavirus (COVID-19) pandemic. A comparative analysis with the National Aeronautics and Space Administration's (NASA's) Orbiting Carbon Observatory-2 (OCO-2) is carried out using the time series data on column-averaged dry air CO₂mole fraction (xCO₂) and solar-induced fluorescence (SIF), a parameter pertinent to CO₂, for nine crowded urban places and nine unpopulated places with negligible human activity, each of 2°x 2°area selected randomly from different global locations. The resulting similarities and dissimilarities in the trends of the seasonal variations of xCO₂and SIF give clear indication of a reduction in the CO₂column average, especially in the crowded urban regions, which experienced restricted fossil fuel burning situation during the global COVID-19 pandemic in year 2020. A wavelet coherence technique is suggested for quantifying the temporary reduction using the OCO-2 data recorded in years 2018-2020 as reference. This methodology is hoped to be useful in future comparison of OCO-3 with its own annual data. IEEE