The ratios I(K1)/I(H1) and I(K3)/I(H3) of CaII as diagnostics of the chromosphere above sunspots

The ratios I(K-1)/I(H-1) and I(K-3)/I(H-3) were calculated from four semi-empirical models of sunspot umbra. We determined the dependencies of both ratios of such parameters as temperature gradient and atmospheric opacity. A certain influence on the expected ratios I(K-1)/I(H-1) and I(K-3)/I(H-3) can also come from the FIP effect provided it exists in the chromosphere above sunspot umbra. Theoretical and observed values of I(K-1)/I(H-1) and I(K-3)/I(H-3) are compared. It is shown that for one of the sunspots we observed, the values obtained for the ratio I(K-1)/I(H-1) cannot be explained in terms of existing umbra models.