Global Climatological and Real-Time Green Vegetation Fraction from AVHRR

The global coverage, 0.144-degree resolution green vegetation fraction (GVF) climatological fields have been derived at weekly temporal resolution using 12-year weekly smoothed NDVI datasets, while such smoothed NDVI datasets were obtained by post-launch calibrated AVHRR visible and near infrared radiances that span over the operational period of NOAA-9, NOAA-11 and NOAA-14 satellites. A comprehensive statistical approach was further developed to utilize both the weekly GVF climatology and the real time vegetation anomaly magnitude indicated by vegetation condition index (VCI) to produce high quality near real-time meso-scale grid resolution global GVF fields that are suitable to use by numerical weather, climate and hydrological models. This approach considers different scenarios of the relationship between GVF anomaly and VCI for each week, land surface class and hemisphere. The case studies show that the resulting GVF fields are capable of capturing real-time moderate to strong land surface vegetation anomaly signals while preserving general trend in the climatological datasets. The data products summarized in this study appear be superior to previously derived GVF climatology.