Forecasting Interannual Space-based CO2 Concentration using Geostatistical Mapping Approach

NASAs Orbiting Carbon Observatory-2 (OCO-2) is a recent satellite mission primarily aimed at measuring the column concentration of the carbon dioxide (CO₂) in the atmosphere. The atmospheric CO₂ concentration is measured as continuous swaths of the parallelogram footprints which are available as the Level-2 samples with a swath width of 10.3 km approximately. The temporal frequency of the retrieval at one place is 16 days approximately. This work attempts to forecast the OCO-2 samples at an interannual time scale from the available past samples at the nearby locations using geostatistical spatiotemporal kriging-based mapping approaches. This forecasting is needed to understand the future seasonal behavior of CO₂ beforehand. For the validation, we have used the XCO₂ swaths of OCO-2 in a study region from 2015 - 2019 and foretasted in the year of 2018 and 2019. One of the variant approaches found to produce 1.52 ppm root mean square error (RMSE), which is a good result with limited samples. This approach is capable of spatio-temporal prediction and forecasting of other products of OCO-2 and might be improved further by considering correlated auxiliary variables in the study region.