NOTICE (July 2017): CDIAC will cease operations on September 30, 2017. Data will continue to be available through this portal until that time. A new DOE data archive is now at Lawrence Berkeley National Laboratory and is named ESS-DIVE. Data stored at CDIAC is being transitioned to ESS-DIVE and will be available from ESS-DIVE by September 30, 2017. If you have any questions regarding the new archive or the data transition, please contact

image image image image

Solar Records: The Wolf Sunspot Index and Umbral/Penumbral Ratio (1985) (NDP-014)

DOI: 10.3334/CDIAC/sar.ndp014

data Data


D. V. Hoyt

These data from observations of sunspot activity cover the period 1875 through 1981; reconstructions are possible back to 1832. Available sunspot models and the theory of mixing length indicate that the observed changes in the umbral/penumbral (U/P) ratio may be equivalent to changes in the solar constant. The U/P ratio is calculated from measurements of solar activity and has been shown to be in good agreement with the Northern Hemisphere temperature record. The data consist of year, number of sunspot groups, Wolf sunspot number, umbra area, whole area, penumbral area, and umbral/penumbral ratio. The data are in one file (3.3 kB).