Parameterized Transmittance Model for Atmospheric and Surface Solar Radiations

• 作者: J. Djampou Tchouankap L. Akana Nguimdo
• 来源期刊: 大气和气候科学(英文)
• 学科: 地球科学
• 关键词: SCATTERING ABSORPTION TRANSMITTANCE Extraterrestrial FLUXES Solar IRRADIATION
• 年，卷（期）: dqhqhkxyw_2020,（1）
• 页码范围: 81-99
• 页数: 19页
• 分类号: P73

摘要

This work describes a transmittance model that evaluates global solar irradiation through the atmospheric column and at surface. The model is based on appropriate determination of the transmission coefficients of the different atmospheric constituents in a plane parallel layers frame and estimates the downward solar fluxes from the upper limit of the atmosphere. In testing this model, we first considered the purely molecular atmosphere to parameterize descending solar fluxes, which allowed us to estimate the attenuation due to atmospheric gases at specific times of the day when the irradiation at ground level is known. The results thus obtained show that the molecular atmosphere has a maximum reduction rate of incident flux (at the Top Of Atmosphere) of 20% with daily profiles that are homogeneous with extraterrestrial fluxes. Considering the turbid and cloudy atmosphere in which the multiple scattering phenomenon is taken into account, we obtain at ground level fluctuating profiles with attenuation rates reaching 64% depending on the time instant in the day. The comparison of our results with the experimental data obtained at the Yaoundé site on one hand and with the results of the CLIRAD-SW model on the other hand shows at monthly scale high correlation, of the order of 0.998. Moreover at monthly time scale, the precision which for some hourly values is relatively low tends towards a net improvement on the seasonal scale where it extends over a narrow domain ranging from 0.02% to 1.66%.