caa a22 4500 445346116 CHVBK 20180317142829.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s11207-011-9724-7 doi (NATIONALLICENCE)springer-10.1007/s11207-011-9724-7 Estimating the Mg ii Index from 1961 Through 1981 Using Ca ii K Images from the Mt Wilson Observatory [Elektronische Daten] [J. Morrill, L. Floyd, R. Ulrich, S. Weaver, D. McMullin] An empirical model of solar UV spectral irradiance has been developed that is based on observed spectral radiance measurements and full disk Caii K images. The Mgii index is then calculated from the estimated spectra in a narrow wavelength range (180Å) near the Mgii doublet at 2800Å. Our long term goal is to expand this wavelength range from 10 to 4000Å in continuing studies based on spectral data covering this wavelength range (e.g. Skylab, UARS/SUSIM, TIMED/SEE, etc.). Our previous modeling effort produced spectra in this 180Å range and the resulting Mgii index values for the period from 1991 through 1995 and we have used observations during this time period to validate the model results. The current paper presents results from this model based on a 21-year portion of the recently digitized CaiiK images from the Mt Wilson Observatory (MWO) film archive. Here we present details of the model, the required model modifications, and the resulting Mgii index from 1961 through 1981. Since the NOAA Mgii index did not begin until 1978, the present model results are compared to a Mgii index estimated from the F10.7 radio flux over this 21-year period. The NOAA Mgii index, which is derived from measured UV spectra, is also included for comparison from late 1978 through 1981. Springer Science+Business Media B.V., 2011 Solar UV spectrum nationallicence Solar activity nationallicence Mg ii index nationallicence Ca ii K activity nationallicence Morrill J. Space Sciences Division, Naval Research Laboratory, Washington, DC, USA aut Floyd L. Interferometrics, 20151, Chantilly, VA, USA aut Ulrich R. University of California, 90095, Los Angles, CA, USA aut Weaver S. NOAA Climate Prediction Center, 20746, Camp Springs, MD, USA aut McMullin D. Space Systems Research Corp., 22314, Alexandria, VA, USA aut Solar Physics Springer Netherlands 270/1(2011-05-01), 109-124 0038-0938 270:1<109 2011 270 11207 https://doi.org/10.1007/s11207-011-9724-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11207-011-9724-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Morrill J. Space Sciences Division, Naval Research Laboratory, Washington, DC, USA aut NATIONALLICENCE 700 1- Floyd L. Interferometrics, 20151, Chantilly, VA, USA aut NATIONALLICENCE 700 1- Ulrich R. University of California, 90095, Los Angles, CA, USA aut NATIONALLICENCE 700 1- Weaver S. NOAA Climate Prediction Center, 20746, Camp Springs, MD, USA aut NATIONALLICENCE 700 1- McMullin D. Space Systems Research Corp., 22314, Alexandria, VA, USA aut NATIONALLICENCE 773 0- Solar Physics Springer Netherlands 270/1(2011-05-01), 109-124 0038-0938 270:1<109 2011 270 11207 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer