At the county level, there were also strong correlations
in the area estimates of paddy rice between MODrice and
NLCD20 (Fig. 9), with RMSE=188 km2 for flat provinces
and RMSE=97 km2 for hilly provinces. The strong
relationship between the two datasets suggests that
MODrice may be a useful tool to provide timely, annual
rice area estimates, if a reference dataset (NLCD20) is used
to constrain the areas of analysis. The MODIS paddy rice
pixels cover a total area of 250,480 km2 (Table 3),
accounting for 89% of total paddy rice area (280,555 km2)
from the NLCD database. From a standpoint of biogeochemical
modeling, these results are very encouraging as
biogeochemical modeling is often performed at the county
scale