Solar Radiation Models and Gridded Databases to Fill Gaps in Weather Series and to Project Climate Change in Brazil

Table 1

Solar radiation-estimating models based on maximum and minimum air temperature.

Model	Equation	Coefficients	Reference
Ha		a	[9]
Hu		b and c	[26]
An		d	[27]
BC		e, f, and	[10]
DC		h, i, and j	[28]

: solar radiation (MJ·m⁻²·d⁻¹); : extraterrestrial solar radiation (MJ·m⁻²·d⁻¹); : thermal amplitude (T_max − T_min) (°C); : 7-day moving average of (°C); a, b, c, d, e, f, , h, and j: coefficients to be adjusted for each model. For BC and DC models, e and h coefficients were determined by a relationship with altitude, , as proposed by Allen et al. [29]. and N are astronomical values calculated according to Allen et al. [30]. Ha: Hargreaves; Hu: Hunt; An: Annandale; BC: Bristow–Campbell; DC: Donatelli–Campbell.