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

Table 2

Comparison of crop model biomass outputs obtained with measured and estimated radiation. Radiation data were produced with the indicated methods. The averages and the confidence intervals (𝛼=0.05) of the error indicators were calculated based on the model results obtained for the 109 investigated stations. The 𝑡-tests were carried out for each station separately using 30-year long simulations.

Estimation method	𝑅^2	RMSE (kg ha^−1)	MRE (%)	Proportion of significant differences based on 𝑡-test (𝛼=0.05) (%)
DC	0.872±0.033	1090±105	5.31±5.49	69
DB	0.937±0.015	764±32	3.46±1.34	33
HKS	0.916±0.026	845±57	3.93±2.55	38
LS	0.952±0.012	625±27	2.84±1.16	15
S^0-2-1-4	0.952±0.014	599±24	2.72±1.02	15