Table 3.
Parameters of semi-variogram models and error statistics of their one-leave-out cross-validation for monthly average daily solar radiation over Turkey.
| Parameters and error statistics | Month | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | |
| Moran's I | 0.12 | 0.12 | 0.1 | 0.07 | 0.03 | 0.03 | 0.02 | 0.04 | 0.06 | 0.1 | 0.13 | 0.12 |
| Major range (a) | 4.74 | 4.74 | 7.46 | 10.66 | 3.2 | 5.33 | 4.03 | 4.03 | 4.03 | 4.14 | 4.74 | 4.74 |
| Partial sill (c) | 0.42 | 0.86 | 1.1 | 0.45 | 0.86 | 0.59 | 1.48 | 1.42 | 0.76 | 0.37 | 0.21 | 0.22 |
| Nugget effect (c0) | 0.65 | 1.01 | 1.77 | 2.26 | 2.9 | 3.95 | 3.74 | 2.89 | 2.33 | 1.28 | 0.7 | 0.43 |
| Ratio of nugget to sill | 0.61 | 0.54 | 0.62 | 0.83 | 0.77 | 0.87 | 0.72 | 0.67 | 0.75 | 0.78 | 0.77 | 0.66 |
| Lag size | 0.4 | 0.4 | 0.63 | 0.9 | 0.27 | 0.45 | 0.34 | 0.34 | 0.34 | 0.35 | 0.4 | 0.4 |
| MPE | -0.04 | -0.04 | -0.12 | -0.09 | -0.1 | -0.17 | -0.13 | -0.1 | -0.1 | -0.08 | -0.07 | -0.04 |
| RMSPE | 0.96 | 1.25 | 1.54 | 1.64 | 1.95 | 2.12 | 2.25 | 2.0 | 1.71 | 1.21 | 0.91 | 0.81 |
| AKSE | 0.97 | 1.22 | 1.52 | 1.65 | 2.03 | 2.19 | 2.23 | 1.99 | 1.74 | 1.27 | 0.94 | 0.78 |
| MSPE | -0.04 | -0.03 | -0.08 | -0.06 | -0.05 | -0.08 | -0.06 | -0.06 | -0.06 | -0.07 | -0.07 | -0.06 |
| RMSSPE | 0.98 | 1.01 | 1.0 | 0.98 | 0.96 | 0.97 | 1.01 | 1.01 | 0.98 | 0.95 | 0.96 | 1.02 |
| R2 (%) for validation | 48.99 | 43.88 | 37.00 | 28.03 | 18.94 | 13.65 | 10.99 | 18.36 | 28.80 | 46.48 | 52.44 | 50.32 |
Ratio of nugget to sill: c0 / (c0 + c); MPE: mean prediction error; RMSPE: root mean square prediction error; AKSE: average kriging standard error; MSPE: mean standardized prediction error; RMSSPE: root mean square standardized prediction error.