Atmospheric Broadband Model for Computation of Solar Radiation at the Earth’s Surface. Application to Mediterranean Climate

Abstract

This paper deals with a new broadband atmospheric model designed for predicting the total and diffuse solar radiation incident on the earth's surface in medium or large-sized coastal or near-coastal cities, under a clear or cloudy sky. The revised LABS (1981, 1984) solar spectrum is used. The atmospheric transmittance of each atmospheric parameter contributing to solar radiation depletion, water vapor, ozone, uniformly mixed gases, molecules and aerosols, is calculated using parameterized expressions resulting from integrated spectral transmittance functions. The beam and diffuse radiation components are obtained as a function of the specific atmospheric transmittances. The model requires the following parameters as inputs: total water vapor and ozone amount in a vertical column, sunshine duration and the surface albedo. The model has been used for validation purposes at two stations with slightly different characteristics (NOA and Penteli) in the Athens basin, where total and diffuse radiation measurements are available, for a period of 34 months for NOA and 23 for Penteli. The NOA station is located on a small hill (107 m a.m.s.l.) near the center of Athens, while the Penteli station (500 m a.m.s.l.) is situated in a relatively less polluted area in northern Athens. The clear sky part of the model was tested for 70 individual ''clear'' days with 2-minute intervals, while the whole model was checked with monthly ''mean'' days and mean hourly values. A close agreement between the calculated and the measured values of total and diffuse solar radiation is observed.

Performance of the meteorological radiation model during the solar eclipse of 29 March 2006

“…Barbaro (1979) allows k=1, but Ideriah (1981) proposed a value of k=0.75 to provide better agreement between estimates and measurements. For the Athens data k was found to vary between 0.85 and 0.95 for the winter months, and be 1.0 for the summer period (Psiloglou et al, 2000).…”

“…The general transmittance function, T i , for seven main atmospheric gases (H 2 O, O 3 , CO 2 , CO, N 2 O, CH 4 and O 2 ) can be expressed by the following equation (Psiloglou et al, 1994(Psiloglou et al, , 1995a(Psiloglou et al, , 1996(Psiloglou et al, , 2000: where m is the optical air mass, and a, b, c, d are numerical coefficients that depend on the specific extinction process; the values of these coefficients are given in Table 1. The optical air mass, m, at standard pressure conditions, is given by Kasten and Young (1989):…”

“…Under clear sky conditions, the diffuse (indirect) sky radiation is assumed to be made up of a portion of singly scattered by the atmospheric constituents (molecules and aerosol particles) direct beam radiation, I ds , plus a multiple scattering component, I dm (Atwater and Brown, 1974;Psiloglou et al, 2000):…”

“…For Athens, the value of ν=0.4 was found to be more appropriate (Psiloglou et al, 2000). Therefore, the diffuse radiation at ground level under cloudy skies, I cd , is the sum of the I cds and I cdm components, i.e.…”

Quantifying Spatiotemporal Dynamics of Solar Radiation over the Northeast China Based on ACO-BPNN Model and Intensity Analysis

“…Radiative transfer models take into account the effects of physical factors (e.g., scattering of atmospheric molecules and aerosols and absorption of carbon dioxide and ozone absorption) and meteorological factors (e.g., cloud amount and sunshine hours) on solar radiation, which make for strong physical attribute characterization architecture. Spectral radiation models and broadband radiation models are representative theoretical models [10][11][12][13][14][15][16][17][18][19][20]. Nevertheless, the structures of these classical models are fairly complex.…”