Quiet-Sun variability in a temperature minimum region

The results of monthly monitoring Ca II K line profiles at a quiet-Sun regi on near solar disk center at Kitt Peak during about two solar cycles since 1974 are presented to investigate the variations of K-1 emission, which is strongly dependent on the temperature minimum region (TMR). Cyclic variatio ns are found in K-1 emission that are similar to those in the sunspot numbe rs. However, there is an evident time lag of about 1.2 yr between the K-1 e mission and the sunspot numbers. Non-LTE computations show that the corresp onding temperature variation and position fluctuation in the quiet-Sun TMR region are estimated to be about 17 K and 1.7 x 10(-2) g cm(-2), respective ly.