Estimation of Solar Insolation and Angstrom–Prescott Coefficients Using Sunshine Hours over Nepal

Table 2

The annual average measured and estimated solar insolation and Angstrom–Prescott parameters for selected meteorological locations.

Location	Altitude masl	Annual average n/N	Annual mea. GSR (MJ/m^2/day)	Annual est GSR (MJ/m^2/day)	PE (%)	Empirical constant (a)	Empirical constant (b)	a + b
Tikapur	149	0.612	15.998	15.865	0.831	0.272	0.374	0.646
Nepalgunj	150	0.598	16.788	16.691	0.578	0.255	0.451	0.706
Kankai	300	0.768	15.856	15.861	−0.032	0.004	0.654	0.658
Dharan	310	0.548	16.407	16.337	0.427	0.291	0.407	0.698
Dipayal	662	0.586	15.006	15.076	−0.466	0.278	0.519	0.797
Dhunibesi	1085	0.485	14.17	14.009	1.136	0.235	0.432	0.667
Darchula	1097	0.404	14.95	15.058	−0.722	0.234	0.592	0.826
Pulchowk	1320	0.535	16.198	16.164	0.210	0.293	0.413	0.706
Khumaltar	1350	0.535	15.95	15.841	0.683	0.271	0.448	0.719
Ilam	1570	0.425	13.064	13.128	−0.490	0.198	0.543	0.741
Okhaldhunga	1720	0.446	14.806	14.971	−1.114	0.215	0.598	0.813
Lumle	1740	0.441	15.553	15.574	−0.135	0.261	0.541	0.802
Jiri	1877	0.424	15.321	15.367	−0.300	0.26	0.564	0.824
Musikot	2100	0.673	18.343	18.258	0.463	0.244	0.532	0.776
Jumla	2383	0.604	19.113	19.045	0.356	0.28	0.553	0.833
Average		0.539	15.835	15.816	0.117	0.239	0.508	0.747