It is planned to provide tools for interpretation of combined hard X-ray, soft X-ray, and optical observations of solar flares by developing self-consistent models of energy transport in flares. The MAX '91 program is providing unprecedented multiwavelength observations of flares during the current solar maximum. In particular, it is planned to compute a grid of physically self-consistent atmospheric models which are in energy balance, including energy transport by nonthermal particles, thermal conduction, and all important radiation processes (X-ray, UV, optical). It is neither necessary or desireable to carry out a fully time-dependent model. It is more useful, for interpretation of the observations to consider two simpler limiting cases: the hydrostatic limit, valid on timescales typically tens of seconds or longer, and the impulsive limit, where the mass is frozen into its preflare distribution. To determine the heating and cooling of the optically thick chromosphere, a rigorous non-LTE treatment of the radiative transfer and statistical equilibrium in all important atomic lines will be employed. These models should provide an important step toward using integrated multi-wavelength observations to discriminate between thermal and nonthermal processes in solar flare chromospheres.
