HR: 0800h
AN: SH41A-1111    [Abstracts]
TI: Initial Estimate of the Mg II Index from 1932 to 1974
AU: * Morrill, J S
EM: morrill@shogun.nrl.navy.mil
AF: Naval Research Laboratory, E. O. Hulburt Center For Space Research, Washington, DC 20852 United States
AU: Weaver, S
SH41A-1111 AF: University of Maryland, Department of Atmospheric and Oceanic Sciences, College Park, MD 20742 United States
AU: Ermolli, I
SH41A-1111 AF: INAF, Astronomical Observatory of Rome, Rome, 12321 Italy
AB: Using a computer model developed at the Naval Research Laboratory to estimate solar UV irradiance and recently digitized solar images of Ca II K emission from 1932 to 1974 we have generated an initial estimate of the Mg II index during this time period. The Ca II K images are from the Arcetri archive and resulted from synoptic observations made from 1925 to 1974 at the Arcetri Astrophysical Observatory, near Florence, Italy. The digitization of images from this archive was recently carried out at the Rome Astronomical Observatory. The Mg II index is an important measure of solar variability but one that has only been measured since the late 1970's. By using these images and our model, estimates of this index can be generated and compared to other proxies of solar irradiance variability used as input to climate studies. In this presentation we will present a brief overview of the computer model and method of estimating the Mg II index, a review of the Ca II K images, and present and future corrections to the Ca II K images. The preliminary Mg II index will be compared to other measures of solar variability.
DE: 0360 Radiation: transmission and scattering
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1650 Solar variability (7537)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 7537 Solar and stellar variability (1650)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005