  Model simulations of solar irradiance reaching the Earth's surface during a
solar eclipse constitute a useful tool for studying the impact of this
phenomenon on the radiance propagation through the atmosphere. A simple
approach to extend the use of an algorithm already adopted for evaluating the
variations in the extraterrestrial solar radiation during a total eclipse is
proposed for a partial eclipse case. The application is based on the assessment
of the distance between the apparent solar and lunar disk centers on the
celestial hemisphere, using the local circumstances and the ratio between the
Sun and Moon radii as input parameters. It was found that during the eclipse of
March 29, 2006, the present approach led to an estimate of the surface UV solar
irradiance trend differing by no more than \pm5% from the corresponding trend
observed at Bologna (Italy).

Atmospheric and Oceanic Physics