Considering Three-Dimensional Effects in Spectral Irradiance Modeling
Han Uitenbroek [huitenbroek@nso.edu], National Solar Observatory, Sunspot, New Mexico
Total spectral irradiance is typically modeled by assigning an atmospheric model to
each pixel of a full disk image and geometrically combining the predicted wavelength
dependent intensity for each of these models into a disk integrated spectrum. This works
reasonably well, as the hydrostatic models that are used in this procedure generally
reproduce observed spectra very well. However, for numerical expedience this scheme
neglects some important physical aspects of the solar atmosphere, in particular its threedimensional and strongly dynamic nature. In this talk I will discuss the importance of
some of these effects on the spectral irradiance signal, using forward radiative transfer
modeling in realistic three-dimensional simulations. Obviously, modeling the threedimensional dynamic structure over the whole disk is computationally prohibitive, but if
some of the effects discussed above are important, strategies will have to be implemented
to incorporate them approximately. Characterizing these contributions to the spectral
irradiance will also help us to better understand the physical nature of the forces that
drive variability, and hopefully improve our predictive capabilities.