Landsat NDVI difference 1990 2018 Tile 1 Jiapeng Qu Fabian Ewald fassnacht Christopher Schiller Teja Kattenborn Xinquan Zhao 10.6084/m9.figshare.7770290.v2 https://springernature.figshare.com/articles/dataset/Landsat_NDVI_difference_1990_2018_Tile_1/7770290 Landsat NDVI difference 1990 2018 Tile 1 2019-05-22 09:10:27 Tibetan Plateau grassland LANDSAT Grassland trends ndvi-difference MODIS Mann-Kendall trend test