Title: Dependence of contrast/area function on the sunspot area databases
Author: A. Ludmány
Affil: Heliophysical Observatory, Debrecen, Hungary
Email: ludmany@tigris.klte.hu
Authors: T. Baranyi
Affils: Heliophysical Observatory, Debrecen, Hungary
Abstract: The irradiance models use the concept of Photometric Sunspot Index (PSI) to account for the influence of sunspots on Total Solar Irradiance (TSI). The sunspot area data are involved in construction of PSI in explicit form and in implicit form by the contrast of the sunspots. The direct photometric measurements published by several authors have shown that the contrast has large variance depending on spots and time but it mainly depends on the area of spots. Our previous comprehensive study of sunspot area databases revealed large systematic differences between the area measurements. In this way the improvement of the sunspot area data set can significantly improve the contrast vs. area function and the irradiance model. In this study we compared the available contrast and sunspot area measurements published in the literature with the recent area data of Debrecen Photoheliographic Results for the year 1988.