Seasonal trend analysis of carbon dioxide across latitudes of Africa, Europe and Asia

Abstract

Carbon-driven emissions are on the rise and much work remains to be done to benchmark seasonal carbon increase and ensure its prompt reduction. There is a great need of new methods for validating seasonal trends of carbon dioxide (CO₂). We obtained CO₂, temperature and normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra satellite from 2003 to 2008 over Africa (Nigeria, Mauritania, Congo, Sudan), Europe (France, Finland, Turkey, Ukraine), and Asia (China, Mongolia, India, Afghanistan). For the first time, seasonal index analysis was used to validate vegetation index. The seasonality in carbon dioxide was determined dividing the monthly average by the annual mean. Additionally, the percentage difference correlation of the NDVI and CO₂ relationship was calculated to investigate the underlying influence of both parameters and validate the seasonal change resulting from the solar activity cycle. By grouping years based on solar activity maximum (2003-2004), intermediate (2005-2006) and very low activity (2007-2008), the results expanded the physical interpretation that seasonal fluctuation of NDVI corresponds to the terrestrial sink of regional CO₂, mostly occurring during equinoctial months. Our results demonstrate that seasonal variation of CO₂ depends on geographic latitude and the solar activity cycle. This result is essential in studying the future trend relationship between NDVI and CO₂.