Radiation amplification factor, RAF

Because of the strong absorption of ultraviolet (UV) radiation starting at 320 nm by 03, one of the major impacts of decreased stratospheric ozone is expected to be increased UV at the earth s surface, with associated effects such as increases in skin cancer and cataracts and damage to plants and other ecosystem components. It has therefore been of great interest to determine whether such a relationship can be detected and, if so, what the magnitude of the effect is. The latter is commonly expressed as an amplification factor (AF) or radiation amplification factor (RAF), defined as the fractional change in radiation (R) per fractional change in total column ozone (03) ... 

The TUV model predicts a Radiation Amplification Factor (RAF) at 305nm of 2.8 which when multiplied by the 0.45% change of ozone per decade gives 1.26% change per year for the irradiance, which is only. 32% per year different from the observational result. This difference is within the uncertainty of the observations. The RAF estimations of the TUV model have been verified from the Brewer measurements and are in accordance with the RAF calculated with the use of equation 2 (WMO, 1998). 

The UV-ERY measurements made at two locations in the Czech Republic were analysed in [7]. The values of the altitude effect and the radiation amplification factor (RAF) and their dependence on SZA were assessed, and the statistical model relating UV-ERY with SZA and total ozone was developed. In this contribution, the main results obtained in that analysis are summarised (Sections 3, 4 and 5) and then the statistical model and the annual cycle of total ozone (Section 6) are used to estimate the... 

The relationship between changes in erythemal irradiance, , and total ozone, Q, is commonly expressed with use of the radiation amplification factor (RAF) ... 

Table 2. Radiation amplification factors (RAF) for various action spectra, calculated for daily totals of solar radiation in July, 30°N, 305 DU ozone amount...

Action spectra can be applied to estimate the biological and chemical impacts of ozone depletion and related UV increases. The fractional increases in biologi-cally-active UVR are amplified compared to the changes in total ozone in the atmosphere. The degree of amplification, or radiation amplification factor (RAF) , is defined by equation (4) ... 

The radiation amplification factor (RAF) is a convenient indicator for correlating the sensitivity of a biological effect to different UV exposures caused by various levels of ozone depletion. - For small variations (about 1 to 10%) of ozone concentration (OC), the RAF can be defined as follows ... 

The altitude effect (Sec. 3) and the radiation amplification factor (Sec. 4) were derived from UV-ERY measurements made simultaneously at two locations in the Czech Republic. The value of RAF obtained from the present data agrees with previous studies of other authors. The value of the amplitude effect agrees with the value used by National Weather Service and EPA [10] but is lower than the values obtained by other authors [2, 9]. The statistical model relating UV-ERY irradiance with total ozone and solar zenith angle was developed (Sec. 5 Fig. 2). Although the information on the total ozone does not satisfactorily improves accuracy of the UV-ERY forecast (further variables should be incorporated into the model to improve its accuracy), the model may be used to estimate annual and daily cycles of sun-visible UV-ERY irradiance for various total ozone levels. The results obtained show variability of the model UV-ERY irradiance related to variability of total column ozone. Specifically, it is demonstrated that the UV-ERY irradiance may exceed the annual/daily normal-ozone maxima during non-negligible portion of the year/day (about 214 months/hours) if the total ozone... 

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