The shape of the inhibition vs. exposure relationship is also important
[Vincent Roy 1993].
Data from the field on UV-induced photoinhibition have been described with
linear
[Ray Smith Baker Holm-Hansen Olson 1980,
Behrenfeld Hardy Gucinski Hanneman Lee Wones 1993],
and sigmoid
[Helbling Villafane Ferrario Holm-Hansen 1992,
Ray Smith Prezelin macintyre 1992] relationships.
These shapes influence the amplification factors (see below).
The scatter in field measurements, usually dependent upon broad-band
exclusion/inclusion techniques, and uncertainties about reciprocity make it
difficult to identify the best form.
However, laboratory results
[Cullen Lesser 1991, Cullen Neale Lesser 1992,
Lesser Cullen Neale science 1992]
can be characterized with inhibition described as a hyperbolic function of
biologically effective irradiance.
The same model works for natural phytoplankton from the Antarctic
[Neale Lesser Cullen Weiler 1994],