The sun as a star - Three-component analysis of chromospheric variability in the calcium K line

A three-component model of the solar cycle variability of the Ca II K emission is developed using extant contrast and fractional area parameters for (1) cell, (2) network, and (3) plage components that are resolution-consistent. A fit has been achieved for the quiet-sun Ca II K emission (at solar minimum) as observed by White and Livingston (1981) with cell and network features alone using extant limb-darkening laws. The occurrence of plages during the growth of the solar cycle was found to be insufficient to account for the cycle increase in the K emission and required the introduction of additional network in excess of the quiet-sun value. The implications of, and evidence for, such an active network are discussed.