Global vegetation dynamics using multiple satellite observations throughout the past four decades

Terrestrial vegetation is a key component of the biosphere, which regulates global carbon, water and energy cycles. Meanwhile, global environmental change is rapidly altering the dynamics of terrestrial vegetation by functioning the Earth system and providing ecosystem services. Therefore, systematically monitoring global vegetation dynamics is critical to understand the basic biogeochemical processes, and their possible feedbacks to the climate system. Besides, characterizing spatial heterogeneity and temporal variation of surface albedo is also great importance to monitor land cover change and to determine energy exchange between ground and atmosphere. 
Remote sensing offers the only effective method for measuring and monitoring the vegetation dynamics, heterogeneity of albedo and its directional signature on regional and global scales. In this study, 4 km × 4 km GAC AVHRR data from extensive satellite data archive collected by the Remote Sensing Research Group at the University of Bern (RSGB) from 1981 to 2022 was applied to analyze albedo coupling with vegetation dynamics over global. The Simplified Method for Atmospheric Correction (SMAC) radiative transfer code was employed to do the atmospheric correction, and Ross-Thick/Li-Sparse-Reciprocal (RTLSR) kernel-driven model was applied using all contemporaneous NOAA and MetOp satellites data for removing anisotropic effects by means of the Bidirectional Reflectance Distribution Function (BRDF). Therefore, it is expected that the new generation of global Normalized Difference Vegetation Index (NDVI) and Albedo products could be produced from 1981 until 2022, which could potentially provide a long-term dataset for global climate change studies. Some preliminary evaluations showed that the new generation of NDVI product follows a generally similar trend to other products such as SPOT VGT, AVH13C1 NDVI, and Terra MODIS NDVI on selected validated sites.