Season Length 2017-present (raster 10 m), Europe, yearly, Sept. 2021

The Season Length (LENGTH), one of the Vegetation Phenology and Productivity (VPP) parameters, is a product of the pan-European High Resolution Vegetation Phenology and Productivity (HR-VPP) component of the Copernicus Land Monitoring Service (CLMS). The Season Length is the number of days between the start and end dates of the vegetation growing season in the time profile of the Plant Phenology Index (PPI). The Plant Phenology Index (PPI) is a physically based vegetation index, developed for improving the monitoring of the vegetation growth cycle. The PPI index values, with 5-day satellite revisit cycle, are first used in a function fitting to derive the PPI Seasonal Trajectories, which is a filtered time series with regular 10-day time step. From these Seasonal Trajectories, a suite of 13 Vegetation Phenology and Productivity (VPP) parameters are then computed and provided, for up to two seasons each year. The Season Length is one of the 13 parameters. The full list is available in the table 3 of the Product User Manual https://land.copernicus.eu/user-corner/technical-library/product-user-manual-of-seasonal-trajectories/ A complementary quality indicator (QFLAG) provides a confidence level, that is described in table 4 of the same manual. The LENGTH dataset is made available as raster files with 10 x 10m resolution, in UTM/WGS84 projection corresponding to the Sentinel-2 tiling grid, for those tiles that cover the EEA38 countries and the United Kingdom and for two seasons in each year from 2017 onwards. It is updated in the first quarter of each year.