Validation and Investigation of Correlations to Determine Daily Mean Values of Climatic Parameters
Ouedraogo Souleymane *
Laboratoire d’Energies Thermiques Renouvelables (LETRE), Université Joseph KI-ZERBO, 03 BP 7021 Ouagadougou 03, Burkina Faso.
Nana G. Gilbert
Laboratoire d’Energies Thermiques Renouvelables (LETRE), Université Joseph KI-ZERBO, 03 BP 7021 Ouagadougou 03, Burkina Faso and Université Lédéa Bernard OUEDRAOGO (ULBO), 01 BP 346 Ouahigouya 01, Burkina Faso.
Lankouandé Roland
Laboratoire de Chimie Analytique et de Physique Spatiale et Énergétique (LACAPSE), Université Norbert ZONGO, BP 376 Koudougou, Burkina Faso and Université Virtuelle du Burkina Faso (UV-BF), Burkina Faso.
Ky S. M. Thierry
Laboratoire d’Energies Thermiques Renouvelables (LETRE), Université Joseph KI-ZERBO, 03 BP 7021 Ouagadougou 03, Burkina Faso.
Kam Sié
Laboratoire d’Energies Thermiques Renouvelables (LETRE), Université Joseph KI-ZERBO, 03 BP 7021 Ouagadougou 03, Burkina Faso.
Bathiebo D. Joseph
Laboratoire d’Energies Thermiques Renouvelables (LETRE), Université Joseph KI-ZERBO, 03 BP 7021 Ouagadougou 03, Burkina Faso.
*Author to whom correspondence should be addressed.
Abstract
This study evaluated selected correlation models for estimating daytime profiles of global solar radiation on a horizontal surface and ambient temperature at a measurement site in Ouagadougou, Burkina Faso. Experimental data were collected using a pyranometer, a K-type thermocouple and a data logger installed at Joseph KI-ZERBO University. Measurements were recorded at five-minute intervals during selected days in December, January, March and April, and monthly average daytime profiles were obtained. Two trigonometric correlations previously used in existing literature were first applied to describe the temporal variation of solar radiation and ambient temperature. In addition, Gaussian-type correlations were developed using non-linear regression in MATLAB to represent the measured profiles. For global solar radiation, the literature-based sine model produced coefficients of determination between 0.96 and 0.98, with RMSE values ranging from 36.3 to 51.3 W/m². The proposed Gaussian model produced R² values between 0.96 and 0.98, with RMSE values ranging from 33.0 to 51.0 W/m². For ambient temperature, the literature-based model gave R² values between 0.94 and 0.97 and RMSE values between 0.55 and 0.76 °C, while the Gaussian model gave R² values between 0.96 and 0.98 and RMSE values between 0.37 and 0.63 °C. The results indicate that both approaches describe the measured daytime profiles with acceptable agreement.
Keywords: Global solar radiation, ambient temperature, Gaussian correlation, trigonometric model, pyranometer, daily mean profile, regression analysis, climatic parameters, model validation