The concept of an amplification factor, A, such
that a 1% decrease in ozone may cause an A% increase in biological effect,
is useful when considering the possible impact of ozone diminution on a
biological system.
This amplification factor has been subdivided into two components
[Nachtwey Caldwell 1975, Green Findley Klenk Wilson Mo 1976,
Rundel Nachtwey 1978, Rundel 1983]:
(i) the ratio of the proportional change in biological effective irradiance,
or dose rate,
, to the
proportional change in total atmospheric column ozone concentration, or
ozone thickness, 
; i.e.,
the radiation amplification factor,
and (ii) the ratio of the percentage change in biological
effect (e.g., reduction in photosynthesis),
, to the proportional change in biologically
effective irradiance,
;
i.e., the biological amplification factor,
so that the total amplification factor is
Radiation amplification factors give the increase of biologically effective irradiance in response to ozone depletion and published values have been reviewed by Madronich et al. [1994]. [Madronich McKenzie Caldwell Bjorn UNEP 1994 changes] Biological amplification factors will be exactly 1.0 only when the biological effects are linear functions of weighted exposures and, as discussed above, that is not always the case. The above unitless sensitivity coefficients were developed in the late 70's when ozone reductions were projected to be 5 to 15%. Madronich [Madronich Granier Impact 1992, Madronich Chapter 1993, Booth Madronich 1994] has pointed out that since the dose versus ozone relationship is nonlinear, the radiation amplification factor, if calculated using Eq.(4), is not constant with ozone concentration over large changes in ozone characteristic of the Antarctic ozone hole. He has proposed a simple power law that provides a more general definition of the dose versus ozone relationship and which results in a sensitivity factor R which is relatively constant for large ozone depletions:
so,
In dealing with inferences based upon radiation amplification factors, it is important to be aware of how the factor was derived, especially when comparing pre-1990 with more recently published results. It should also be noted that there are very few recent data with respect to the estimation of biological amplification factors except for the nonlinear function of Cullen and coworkers. However, it is not known if their results can be applied directly to the representation of natural populations for time scales greater than one hour, which is necessary for an overall assessment of ozone-related effects.
A reduction in the thickness of the ozone layer leads to an
increase in UV-B radiation.
This will have a large effect for biological weighting functions which
are heavily weighted in the UV-B region
(eg., DNA) with R > 1.
Conversely, biological weighting functions weighted outside the UV-B region,
in particular those weighted in the UV-A spectral region,
will have smaller direct effects (R < 1).
Radiation amplification factor, R, for
selected biological weighting functions plotted in Fig. 1 and calculated using Eq.(8), and averaged over latitude and time, are 0.07 for photoinhibition of
chloroplasts [Jones and Kok kinetics 1966], 0.31 for a marine phytoplankton [Cullen and Neale,1993], 0.51 for plants [Rundel 1983] and 1.67 for DNA [Hunter 1979] which quantitatively demonstrates the R increases with
increased dependence on UV-B.