Historical Reconstruction of Solar Activity

Authors: D.G. Preminger and S.R. Walton

Affiliation: CSUN/San Fernando Observatory

Many of the solar activity indices of interest to researchers in both the solar irradiance and the climate modeling communities have only been measured in relatively recent times. However, sunspot positions and areas have been recorded regularly for a very long time. Sunspot indices, when smoothed, are broadly similar to other smoothed indices. But when considered on a daily basis, sunspot measures are not directly proportional to other indicators of solar magnetic activity. In this work we examine the detailed relationship between measures of sunspot activity and other solar activity indices. We find that these relationships are well defined and can be used for historical reconstruction of other solar activity indices such as the 10.7cm radio flux and the Magnesium II core/wing ratio.

This work was supported by NSF grant ATM-9912132 and NASA grant NAG5-12905.