The raster file is the time series of the start of the vegetation growing season. The start of the growing season time-series is based on the time series of the Plant Phenology Index (PPI) derived from the MODIS BRDF-Adjusted Reflectance product (MODIS MCD43 NBAR). The PPI index is optimized for efficient monitoring of vegetation phenology and is derived from the source MODIS data using radiative transfer solutions applied to the reflectance in visible-red and near infrared spectral domains. The start of season indicator is based on calculating the start of the vegetation growing season from the annual PPI temporal curve using the TIMESAT software for each year between and including 2000 and 2016.

This dataset is based on the Environmental Stratification of Europe (EnS) dataset from the University of Edinburgh, a statistically derived land classification which provides a novel global spatial framework for the integration and analysis of ecological and environmental data (Metzger, Marc J. 2018). It provides a robust spatial analytical framework for the aggregation of local observations, identification of gaps in current monitoring efforts and systematic design of complementary and new monitoring and research. The version 8 of the source EnS dataset, used for the creation of this dataset, distinguishes 84 strata that are relatively homogeneous in environmental conditions and can be aggregated into 13 environmental zones: • Alpine North (ALN) • Boreal (BOR) • Nemoral (NEM) • Atlantic North (ATN) • Alpine South (ALS) • Continental (CON) • Atlantic Central (ATC) • Pannonian (PAN) • Lusitanian (LUS) • Anatolian (ANA) • Mediterranean Mountains (MDM) • Mediterranean North (MDN) • Mediterranean South (MDS) The original dataset (vector format, 1 km spatial resolution) has been rasterised into pixel size of 100m to align with Corine Land Cover. Its spatial coverage has been extended as follows: • Turkey is covered only partially in the original dataset. Missing parts are supplemented by a comparable national dataset provided by the Ministry of Environment and Forestry of Turkey. • The dataset is extended along the coastline to fully cover the spatial extent of CORINE Land Cover. • Canary Islands, Madeira archipelago and the Azores are not included in the original dataset and added as environmental zone “Macaronesia (MAC)”. • Iceland is not included in the original dataset and added as environmental zone “Arctic (ARC)”