0 Fe b 20 06 Impact of Varying Atmospheric Profiles on Extensive Air Shower Observation : - Fluorescence Light Emission and Energy Reconstruction

Several experiments measure the fluorescence light produced by extensive air showers in the atmosphere. This light is converted into a longitudinal shower profile from which information on the primary energy and composition is derived. The fluorescence yield, as the conversion factor between light profile measured by EAS experiments and physical interpretation of showers, has been measured in several laboratory experiments. The results, however, differ considerably. In this article, a model calculation of the fluorescence emission from relevant band systems of nitrogen in dependence on wavelength and atmospheric conditions is presented. Different calculations are compared to each other in combination with varying input parameters. The predictions are compared with measurements and the altitude-dependence of the fluorescence yield is discussed in detail.