Improving the S-Shape Solar Radiation Estimation Method for Supporting Crop Models

Table 4

Error indices of the crop model biomass results for the validation sites. Asterisks denote significant differences (𝛼=0.05). Crop model results obtained with measured radiation were compared to those obtained with the S^0-2-1-4 method parameterized according to Section 3.3.

Site	𝑅^2	RMSE (kg ha^−1)	MRE (%)
Columbus, OH	0.955	1222	4.6*
Fort Smith, AR	0.934	901	3.7
Jackson, MS	0.953	916	4.6*
Kansas City, MO	0.947	783	2.9
Louisville, KY	0.979	534	2.4
Omaha, NE	0.910	841	3.0
Memphis, TN	0.913	1050	5.4*
Springfield, IL	0.984	516	2.5
Waterloo, IA	0.987	533	1.9
Wichita, KS	0.988	468	2.3