Solar Features Faint but Still Present in 2009
Abstract
The San Fernando Observatory (SFO) full-disk photometric image archive spans twenty years and includes the cycle 22/23 minimum and the current cycle 23/24 extended minimum. We measure sunspot deficit, faculae/plage/network excess, and disk-integrated variability on red continuum (672.3 nm) and Ca II K-line (393.4 nm) images. A combined plage/network index shows excess remaining above zero as the cycle 23/24 minimum progresses while plage excess alone drops to zero, indicating an absence of large-scale bright regions but a continuing presence of diffuse network. We construct feature-based models of TSI variability and compare our models to the PMOD, ACRIM, and IRMB TSI Composites to determine whether our data reflect the extremely low TSI levels deduced from spacecraft measurements during the current extended solar minimum.
- Publication:
-
AAS/Solar Physics Division Meeting #40
- Pub Date:
- May 2009
- Bibcode:
- 2009SPD....40.1104C