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Comparisons of MODIS LAI Products and LAI Estimates Derived from Landsat TM

Numerous pre- and post-launch validation researches have been applied on the MODIS LAI products. However, the validation activities were mainly located in North America, Europe and Africa. The validated vegetation types were mainly focused on woodlands (broadleaf forest, coniferous forest and shrubland) and savannas (woody savannas and savannas). In this study, we evaluated the Collection 4 MODIS LAI (MOD15A2) products in North China Plain, with emphasis on the croplands, by: (1) deriving empirical LAI validation maps, based on in situ measurements and Landsat Thematic Mapper (TM) images; (2) conducting initial MODIS validation exercises to assess the quality of MODIS products. The results indicated the MODIS LAI products could resemble the general patterns of the LAI seasonal variation of vegetations in North China Plain, but MODIS LAI algorithm had underestimated LAI values obviously (down to 2-3 m 2 /m 2 ). Biome misclassification and cloud effect were thought to be the main reasons for the significant underprediction of MODIS LAI products.