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Published online by Cambridge University Press: 13 May 2016
CaII K line has been measured regularly nearly every month since 1974 at Kitt Peak. Our study on the data of CaII K profiles over two solar cycles indicates that in center disc spectra, the distance of the K1 component of the CaII K line from the line center and its intensity show periodical variations, but has a time delay of 1.2 years with respect to the sunspot number. Non-LTE computation implies a cyclic temperature variation of about 17 K of the temperature minimum region (TMR) in the quiet-Sun atmosphere and a cyclic variation of about 15-20 km of the position of the TMR.