Need to develop a model for measuring inter-annual and seasonal variability in pasture cover using modis 16 day composites

Aiming to use statistical methods in ArcGis and Envi image analysis to measure inter-annual and seasonal variability in paster cover using MODIS 16 day composite image from 2000-2014. Quite stuck on where to start and any information of links to papers or previous analysis' of a similar style would be greatly appreciated.