Comparison of Debrecen and Mount Wilson/Kodaikanal sunspot group tilt angles and the Joy's law

TL;DR

This paper compares long-term sunspot group tilt angle data from Debrecen, Mount Wilson, and Kodaikanal, analyzing deviations and proposing methods to improve data quality for better understanding of solar magnetic activity.

Contribution

It introduces new tilt angle databases from Debrecen and compares them with existing datasets, analyzing deviations and proposing methods to enhance data quality for solar dynamo studies.

Findings

New tilt angle databases from Debrecen are established.

Deviations among different datasets are analyzed and quantified.

Refined Joy's law diagram demonstrates improved data quality.

Abstract

The study of active region tilt angles and their variations in different time scales plays an important role in revealing the subsurface dynamics of magnetic flux ropes and in understanding the dynamo mechanism. In order to reveal the exact characteristics of tilt angles, precise long-term tilt angle data bases are needed. However, there are only a few different data sets at present, which are difficult to be compared and cross-calibrate because of their substantial deviations. In this paper, we describe new tilt angle data bases derived from the Debrecen Photoheliographic Data ($DPD$) (1974--) and from the SOHO/MDI-Debrecen Data ($SDD$) (1996-2010) sunspot catalogues. We compare them with the traditional sunspot group tilt angle data bases of Mount Wilson Observatory (1917-85) and Kodaikanal Solar Observatory (1906-87) and we analyse the deviations. Various methods and filters are investigated which may improve the sample of data and may help deriving better results based on combined data. As a demonstration of the enhanced quality of the improved data set a refined diagram of the Joy's law is presented.