Comparison of empirical models to estimate monthly mean diffuse solar radiation from measured data: Case study for humid-subtropical climatic region of India

2017 ◽  
Vol 77 ◽  
pp. 1326-1342 ◽  
Author(s):  
Basharat Jamil ◽  
Naiem Akhtar
Keyword(s):  
Solar Radiation ◽  
Empirical Models ◽  
Measured Data ◽  
Climatic Region ◽  
Diffuse Solar Radiation

scholarly journals Improved empirical models for estimating surface direct and diffuse solar radiation at monthly and daily level: A case study in North China

2019 ◽  
Vol 43 (1) ◽  
pp. 80-94 ◽  
Author(s):  
Yao Feng ◽  
Dongmei Chen ◽  
Xinyi Zhao
Keyword(s):  
Solar Radiation ◽  
North China ◽  
Field Measurements ◽  
Empirical Models ◽  
Energy Utilization ◽  
Total Solar Radiation ◽  
Diffuse Solar Radiation ◽  
Precise Knowledge ◽  
The Impact

Precise knowledge of direct and diffuse solar radiation is important for energy utilization and agricultural activities. However, field measurements in most areas of the world are only for total solar radiation. The satellite-retrieved direct and diffuse solar radiation show poor performance under overcast skies. Therefore, better empirical models are needed to estimate direct and diffuse solar radiation by considering the impact of aerosols over polluted regions. A case study is conducted in North China with the ground-measured solar radiation and satellite-retrieved aerosol optical depth to improve new empirical models at monthly (from 2000 to 2016) and daily (from 2006 to 2009) level. The improved empirical models are validated using the field measurements and compared with the existing models. Results suggest that these models perform well in estimating direct solar radiation at monthly ( R2 = 0.86–0.91, RMSE = 0.76–0.83 MJ/m2) and daily ( R2 = 0.91–0.94, RMSE = 1.51–1.64 MJ/m2) level. The accuracy of estimated monthly ( R2 = 0.95–0.96, RMSE = 0.57–0.65 MJ/m2) and daily ( R2 = 0.91–0.93, RMSE = 1.09–1.15 MJ/m2) diffuse solar radiation, particularly the maximum diffuse solar radiation value, has been improved compared to the existing models. The models presented in this study can be useful in the improvement and evaluation of solar radiation dataset over polluted regions similar to North China.

Hourly Distribution of Diffuse Illuminance

2003 ◽  
Author(s):  
V. V. Satyamurty ◽  
P. Ravikumar
Keyword(s):  
Solar Radiation ◽  
Data Base ◽  
Measured Data ◽  
Diffuse Solar Radiation ◽  
Hourly Distribution ◽  
Suitable Modification

It has been found that the values of ratio of hourly diffuse illuminance to daily diffuse illuminance, rvd, are very close to the corresponding values for diffuse solar radiation, rd, examined from the measured data of two locations. This has been further confirmed by examining the values for rvd and rd as calculated from TMY2 [1] data base for primary locations. Based on this, it has been proposed that the correlations available in literature to predict rd can be employed to predict rvd Adequacy of the correlation due to Satyamurty and Lahiri [2] available for rd has been examined to predict rvd as obtained from TMY2 data base for the 56 primary locations. It has been found that the values of rvd obtained from measured illuminance data of two locations have been predicted within a rms difference of 7.1% and within a rms difference of 4.3% for the 56 primary locations of TMY2 data when the correlation due to Satyamurty and Lahiri for rd has been employed after suitable modification.

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