The second comparison, the fractional area-based comparison,
directly uses the fractional values of paddy rice in
the NLCD dataset to calculate the areas for all the MODISbased MODISbased
paddy rice pixels. In the fractional area-based
comparison, there were strong linear relationships in area
estimates of paddy rice at the province level between
MODrice and NLCD20 (Fig. 8), with RMSE=8434 km2 for
flat provinces and RMSE=5041 km2 for hilly provinces.
However, the actual area estimates that are compared in this
validation exercise show a strong topographical effect. With
the exception of Zhejiang Province, the rice area of all the
flat provinces was overestimated by MODrice compared to
NLCD20 fractional area, while all of the hilly provinces
were underestimated by MODrice