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I deduced a 3-D sunspot model that is in agreement with spectropolarimetricobservations, to address the question of penumbral heating by the repetitiverise of flow channels. I performed inversions of data taken simultaneously ininfrared and visible spectral lines. I used two independent magnetic componentsto reproduce the irregular Stokes profiles in the penumbra. I studied theaveraged and individual properties of the two components. By integrating thefield inclination to the surface, I developed a 3-D model of the spot frominversion results without intrinsic height information. I find that theEvershed flow is harbored by the weaker of the two field components. Thiscomponent forms flow channels that show upstreams in the inner and midpenumbra, continue horizontally as slightly elevated loops throughout thepenumbra, and finally bend down in the outer penumbra. I find several examples,where two or more flow channels are found along a radial cut from the umbra tothe outer boundary of the spot. I find that a model of horizontal flow channelsin a static background field is in good agreement with the observed spectra.The properties of the flow channels correspond very well to the simulations ofSchlichenmaier et al. (1998). From the temporal evolution in intensity imagesand the properties of the flow channels in the inversion, I conclude thatinterchange convection of rising hot flux tubes in a thick penumbra still seemsa possible mechanism for maintaining the penumbral energy balance.

A 3-D sunspot model derived from an inversion of spectropolarimetric observations and its implications for the penumbral heating