Modelling the seasonal CO₂ uptake by land vegetation using the global vegetation index

Abstract

An algorithm is developed to calculate the seasonal carbon exchange flux between the living parts of the vegetation and the atmosphere by using monthly time series of NDVI satellite data, air temperature and photosynthetically active radiation. The algorithm is based on already-existing models of the optical and physiological properties of the plant cover, introducing the concept of a seasonally variable green cover and considering some primary plant processes driven by climatic variables. The resulting carbon flux is compared to fluxes obtained by simpler models for one example pixel in Northern Germany during a period of 2 years, showing significant differences in timing and shape. In addition, the seasonal carbon exchange rate measured for beech trees is compared with the corresponding flux derived from the proposed model.