Land surface phenology is defined as the seasonal pattern of variation in vegetated land surfaces observed from remote sensing. Land surface phenology is distinct from the traditional definition of phenology. The traditional definition refers to specific life cycle events using in-situ observations of individual plants or species, while the land surface phenology observed from remote sensing is aggregated information at the spatial resolution of satellite sensors. Currently, satellite sensors with a frequent repeat cycle provides synoptic information to study land surface phenology across the landscape. Both the temporal frequency of the data and the moderate spatial resolution make this sensor well suited for studying continental/global phenology related to the timing of vegetation cycles at seasonal and interannual time scales.

MOD15PHN is estimated from MCD15A2 8-day products. The spatial resolution is 1-km. MOD15PHN is stored in Hierarchical Data Format (HDF) in sinusodial projection, same as other standard MODIS land products.

For the first 11 phenology parameters, only the first two seasons (marked as s1 and s2) are stored if there are more than one valid seasonal cycles detected. Valid seasonal cycles should begin within the year of interest and end before the end of the second year. There are 27 Science Data Sets (SDS) in the available phenology product.

For the details of the temporal smoothing and the spatial gap filling algorithms used, see the User Guide for MOD09PHN and MOD15PHN products.