Total solar irradiance and UV spectral solar irradiance have been monitored
since 1978 through a succession of space missions. This is accompanied by the
development of models aimed at replicating solar irradiance by relating the
variability to solar magnetic activity. The NRLSSI and SATIRE-S models provide
the most comprehensive reconstructions of total and spectral solar irradiance
over the period of satellite observation currently available. There is
persistent controversy between the various measurements and models in terms of
the wavelength dependence of the variation over the solar cycle, with
repercussions on our understanding of the influence of UV solar irradiance
variability on the stratosphere. We review the measurement and modelling of UV
solar irradiance variability over the period of satellite observation. The
SATIRE-S reconstruction is consistent with spectral solar irradiance
observations where they are reliable. It is also supported by an independent,
empirical reconstruction of UV spectral solar irradiance based on UARS/SUSIM
measurements from an earlier study. The weaker solar cycle variability produced
by NRLSSI between 300 and 400 nm is not evident in any available record. We
show that although the method employed to construct NRLSSI is principally
sound, reconstructed solar cycle variability is detrimentally affected by the
uncertainty in the SSI observations it draws upon in the derivation. Based on
our findings, we recommend, when choosing between the two models, the use of
SATIRE-S for climate studies