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Table 7 Regression models to estimate solar radiation directly from cloud cover fraction

From: Estimation of solar radiation from cloud cover data of Bangladesh

# Model type Equations R 2 MBE MPE MARE RMSE t-stat
1 Linear \(H/H_0 = -0.2302C + 0.5713\) 0.9936 0.0213 0.6566 0.0716 0.3315 0.2139
2 Quadratic \(H/H_0 = -0.4585C^2 + 0.2087C + 0.4942\) 0.9953 0.0157 0.4905 0.0585 0.2834 0.1850
3 Third degree \(H/H_0 = 1.9104C^3 - 3.1785C^2 + 1.3352C + 0.3669\) 0.9954 0.0135 0.4482 0.0481 0.2831 0.1593
4 Fourth degree \(H/H_0 = -11.449C^4 + 23.22C^3 - 16.729C^2 +4.7227C + 0.0963\) 0.9957 0.0008 0.8008 0.0543 0.2721 0.0098
5 Fifth degree \(H/H_0 = 120.19C^5 - 299.15C^4 + 281.59C^3 -124.07C^2 + 25.073C - 1.3032\) 0.9974 0.0151 0.1131 0.0344 0.2107 0.2395
6 Logarithmic \(H/H_0 = -0.083\ln (C) + 0.386\) 0.9905 0.0164 0.8877 0.0909 0.4052 0.1347
7 Exponential \(H/H0 = 0.5819exp^{(-0.509C)}\) 0.9931 0.0362 0.3475 0.0728 0.3445 0.3505
8 Power \(H/H0 = 0.3862C^{(-0.184)}\) 0.9899 0.0376 0.4436 0.0916 0.4184 0.2994