Comparison between the range of the observed spectra on the disk for 2008–2009 (between black curves) and the predicted spectra, assuming two coronal layers with T_H = 615 kK and 1.5 MK, and with T_e = 615 kK elsewhere in the corona (blue curves). The continuous line corresponds to h₃ = 20 Mm and h₂ = 10 Mm, the dotted line to h₃ = 10 Mm and h₂ = 28 Mm and Mm, and dashed line to h₃ = 28 Mm and h₂ = 1.7 Mm.