Reconstruction and Prediction of Ultraviolet and Total Solar Irradiance

Heliophysics,Inc., Nahant MA

Investigators

Abstract

The PI will ascertain the reliability of his prior 2002 UV flux and total solar irradiance (TSI) reconstructions, using two new data bases that have become available since that study. He will compare his 2002 reconstructions for the period 1915-1999 (where he used Mt. Wilson (MTW) and Sacramento Peak Ca K images), with results now emerging from UCLA's NSF-funded re-digitization of MTW data for the period 1915-1984, as well as with those from manual reduction and digitization of data for the period 1907-1995 from the Kodaikanal (India) Ca K archive. In order to expedite this data comparison, the PI will organize an open international workshop in the US for wide community participation. The PI will also use the white light facular record, compiled by the Royal Greenwich Observatory (RGO) in the United Kingdom between 1874 and 1976, to extend his irradiance reconstruction backward in time by a further 50%. The ratio of facular and sunspot areas early in a sunspot cycle has been shown to be a good predictor of sunspot cycle amplitude during the RGO observation period. The PI will measure this ratio on white light images obtained after the end of the RGO record in 1976, to test (and potentially extend) the utility of this sunspot activity predictor. This research is important to climate studies and to the interpretation of global warming observations. This project presents a plan for reconstructing, physically describing, and ultimately predicting solar radiative input variations to the Earth. The PI has published copiously on this subject and has been active in public outreach activities. He founded the East Point Solar Observatory in 1995 in Nahant, Massachusetts, and has organized a local NASA-sponsored children's summer astronomy program.