Cyclic Variation in the Solar Lower Atmosphere
Abstract
CaII K line has been measured regularly nearly every month since 1974 at Kitt Peak. It is known that the K1 component of the CaII K line is formed in the temperature minimum region (TMR) of the solar atmosphere. Our study on the data of CaII K line profiles over nearly two solar cycles indicates that both in full disc integrated spectra and in disc-center spectra, the distance between red K1 and blue K1 and its mean intensity show periodical variations, but the former fluctuates in the same way as the sunspot number does, while the later has a time delay with respect to the sunspot number. Non-LTE computation indicates a cyclic temperature variation of about 15 K of the TMR in the quiet-Sun atmosphere and a cyclic variation of about 15-20 km of the position of the TMR.
- Publication:
-
Recent Insights into the Physics of the Sun and Heliosphere: Highlights from SOHO and Other Space Missions
- Pub Date:
- 2001
- Bibcode:
- 2001IAUS..203..387F