Start-of-season value 2017-present (raster 10m and 100m), Europe, yearly, Nov. 2022 - adjusted to the HRL grid

The Start-of-Season Value (SOSV), 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 Start-of-Season Value (SOSV) provides the value of the Plant Phenology Index (PPI) at the start of the vegetation growing season. 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 Start-of-Season Value is one of the 13 parameters. The full list is available in the table 3 of the Product User Manual in the below link section. A complementary quality indicator (QFLAG) provides a confidence level, that is described in table 4 of the same manual. The SOSV dataset is made available as raster files with 10 x 10m and 100 x 100m resolutions, in ETRS89-LAEA projection corresponding to the HRL 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.

季始值（Start-of-Season Value，SOSV）是植被物候与生产力（Vegetation Phenology and Productivity，VPP）参数之一，为哥白尼陆地监测服务（Copernicus Land Monitoring Service，CLMS）泛欧洲高分辨率植被物候与生产力（High Resolution Vegetation Phenology and Productivity，HR-VPP）组件的产出产品。季始值（SOSV）可提供植被生长季始期的植被物候指数（Plant Phenology Index，PPI）数值。植被物候指数（PPI）是一种基于物理机制的植被指数，专为优化植被生长周期监测工作研发。该PPI指数的卫星重访周期为5天，其数值首先被应用于函数拟合以推导PPI季节轨迹——这是一类经滤波处理、时间步长规整为10天的时序序列。基于上述季节轨迹，可计算并生成一套共计13项植被物候与生产力（VPP）参数，每年最多可输出两个季次的对应数据，季始值便是这13项参数之一。完整参数列表可参阅下文链接章节中《产品用户手册》的表3。配套的质量指示因子（QFLAG）可提供数据置信水平，相关说明可参见同一手册的表4。SOSV数据集以栅格文件形式发布，分辨率涵盖10×10米与100×100米两种，采用匹配高分辨率栅格（HRL）网格的ETRS89-LAEA投影坐标系，覆盖EEA38成员国与英国的对应瓦片，数据时段为2017年起的每年两个季次，且于每年第一季度完成更新。