“…Many approaches have been developed to estimate surface solar radiation accurately (Khatib et al, ; Liu et al, ; Olatomiwa et al, ; Sun et al, ; Wang et al, ; Zhang et al, ), which can be generally categorized as follows: - Estimation by semiempirical and semiphysical formulae with conventional meteorological parameters (e.g., sunshine hour, cloud, temperature, and humidity) as inputs (Angstrom, ; Davies et al, ; Thornton & Running, ; Bakirci, ; Besharat et al, ; Hassan et al, ; Liu et al, ). A simple empirical model can be established with its coefficients varying with time and space, which need to be calibrated using long‐term radiation observation data in certain areas.
- Estimation by the artificial neural network method with meteorological observations (Jiang, ; Linares‐Rodriguez et al, ; Tang et al, ; Ramedani et al, ; Kashyap et al, ; Wang et al, ). The artificial neural network method requires a large number of samples to train the model in a local area, and the trained model may not be applicable in other areas.
- Retrieval by satellite‐based radiation (Ceballos, ; Liang et al, ; Mueller et al, ; Lu et al, ; Huang et al, ; Qin et al, ; Ma & Pinker, ; Jia et al, ; Zhang et al, ).
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