Solar radiation spectral

Bond albedo, ratio of reflected solar radiation to incident solar radiation. Spectral range should be specified, for example, visual bond albedo. Diameter, angular extent of disk when planet-Earth distance is greatest (min.) and least (max). 

Comparison with other Studies. How do the results of our investigation compare with similar studies Our results corroborate the data provided in a similar study of the effect of UV-B on primary productivity in the southeastern Pacific Ocean (35). In the latter study, it was noted that enhanced UV-B radiation caused significant decreases in the productivity of surface and deep samples. Compared to ambient, primary productivity decreased with increasing doses of UV-B. In another study in which in situ experiments using natural Antarctic phytoplankton populations, it was noted that incident solar radiation significantly depressed photosynthetic rates in the upper 10-15 meters of the water column (36). It was also found that the spectral region between 305 and 350 nm was responsible for approximately 75 percent of the overall inhibitory effect. 

The spectral distribution of this radiation is given in Table 4.3, from which we can easily see that radiation with wavelengths below 150nm represents only a tiny fraction of the total. The energy distribution of the solar radiation corresponds to that from a black body with a temperature of around 5,000 K. 

Table 4.3 Spectral distribution of the optical solar radiation in the Earth s atmosphere. Data taken from the Smithsonian Physical Tables (1959)...

Specific solar radiation conditions are defined by the air mass (AM) value. The spectral distribution and total flux of radiation outside the Earth s atmosphere, similar to the radiation of a black body of 5,900 K, has been defined as AM-0. The AM-1 and AM-1.5 are defined as the path length of the solar light relative to a vertical position of the Sun above the terrestrial absorber, which is at the equator when the incidence of sunlight is vertical (90°) and 41.8°, respectively. The AM-1.5 conditions are achieved when the solar flux is 982 Wm2. However, for convenience purpose the flux of the standardized AM-1.5 spectrum has been corrected to 1,000 Wm2. 

Fig. 13.1 Spectral characteristics of the solar radiation at the top of the atmosphere and after passing through the atmosphere to sea level...

King, M. D., L. F. Radke, and P. V. Hobbs, Determination of the Spectral Absorption of Solar Radiation by Marine Stratocumulus Clouds from Airborne Measurements within Clouds, J. Atmos. Sci, 47, 894-907 (1990). 

Fluorescence is not useful simply for chemical analysis. For example, a fluorescent additive that sticks to textile fibres is added to laundry soap. This compound absorbs solar radiation in the non-visible part of the spectrum and re-emits at longer wavelengths in the blue spectral region, which makes clothing appear whiter. Another application of fluorescence encountered daily is cathode tube lighting. The internal walls of these tubes are covered with mineral salts (luminophores) that emit in the visible region due to excitation by electrons. 

Leckner. B. (1978) The spectral distribution of solar radiation at the Earth s surface - elements of a model. Solar Energy.. 20, 143. 

In principle, there are two ways to achieve the radiometric calibration of an instrument measuring solar radiation. The first is by comparison to a standard radiation source of known output and the second by comparison to a prototype standard instrument that is capable in measuring the same radiometric quantity. The fist can be applied to broadband detectors only if their spectral response over the whole range of the radiation source is known with sufficient accuracy. The second method requires that the standard instrument has exactly the same spectral response, which is rather unlikely to occur. 

From its principle of operation, a broadband detector provides a signal proportional to the integral of solar radiation 1(1), weighted by its relative spectral responsivity w(X), over its entire sensitivity range. Therefore, the eiythemal dose rate E given in units of W ffm 2 can be than given from (1) ... 

This calibration factor can be determined at any instant from (1), if the spectrum of solar radiation (from the sun and sky) can be measured in absolute units and if the detector s relative spectral sensitivity w(X) is known. 

Covering a wide spectral range, solar radiation is divided roughly into two equal energy portions—the ultraviolet and visible in the 0.25- to 0.7-micron wave lengths, and the infrared out to about 2 or 2.5 microns. 

ADEOS An improved, satellite Earth-observing system equipped with modernized radiometer of the visible and near-IR intervals (AYNIR), ocean color and temperature scanner (OCTS), and radiometer POLDER to carry out global systematic measurements of polarization and spectral characteristics of solar radiation reflected by the Earth-atmosphere system. The satellite ADEOS-2/ Midori-2 was launched on December 14, 2002 by the Japan Space Agency and is an ideal means of global monitoring. 

Solar radiation consists of photons of different energies E. Of particular interest is the spectral distribution n(E), which describes how the photons are distributed over the different energy values. The quantity n(E) indicates the number of photons of specific energy E per unit surface area per unit energy per unit time. From this distribution we define the total photon flux as... 

Both these effects require knowledge of the spectral and spacial radiation distributions of the radiation flux on a surface. The determination of both these distributions at a given location is a difficult instrumentation problem. In this paper, the effect of scattering processes in the atmosphere on the available energy of solar radiation on a surface is examined. Both the spectral and spacial effects of Rayleigh scattering are demonstrated. 

The measurement of the spectral distribution of solar radiation outside the atmosphere and the subsequent association of this spectral distribution with the spectral distribution of radiation in a blackbody cavity has, I believe, biased the attempts to characterize the actual radiation in the atmosphere to an undue extent. Figure 1 indicates typical spectral distributions of radiation in the atmosphere as compared to that of solar radiation outside the atmosphere. Outside the atmosphere m 0 and if the flux is directly through m 1. If slanted at and angle from the zenith angle 90, then m is approximately 1/cos 60. 

Figure 1. Spectral distribution of direct solar radiation through a clear atmosphere of different air masses.

Figure 2. Spectral distribution of scattered solar radiation compared to extraterrestrial and direct solar radiation.

In dealing with problems of solar radiation, as opposed to blackbody radiation, the effect of the solid angle in which the radiation is confined has been examined (2-4) by considering the volume density of photons to be reduced. Landsberg(6) considers dilute radiation in the sense that the spectral distribution is retained but the radiation density is reduced. This leads to defining the temperature of a spectral component as... 

---