On Thursday, July 14th, 2022, at 12 a.m., the thesis reading of the doctoral student Víctor de Paula Vila will take place in the Ebro Observatory library, entitled “Temporal Evolution, Characterization and North-South Asymmetry of Solar Activity using Ebro Observatory Records of Sunspot and Solar Plage Groups during 1910-1937”, which has been carried out under the direction of Dr. Juan José Curto Subirats. The doctoral student is part of the PhD Program in IT and the Aplication to Management, Architecture and Geophysic from La Salle Campus Barcelona.
The heliophysics catalogues published annually by the Ebro Observatory in the period 1910—1937 (both inclusive) have recently been digitized by using optical character recognition technology in order to analyze the data computationally. This has made it possible to study simultaneously some aspects of solar activity in terms of two different solar structures located in two different layers of the solar atmosphere: the sunspot groups (Photosphere) and the solar plage groups (Chromosphere).
The PhD Thesis is made up of three main topics. The first one is the evolution over time of the occurrence daily rate (TOD) and the distribution in percentage of the sunspot and solar plage groups classified according to the different morphological classes, and also according to four intervals of areas. The second topic of the Thesis deals with the morphological evolution of sunspot and solar plage groups throughout their lives by using a first-order Markov chain model.
The third and last topic of the Thesis focuses on the cyclic behavior detected in the N-S asymmetry of the monthly sum of areas and daily occurrences of sunspot and solar plage groups recorded at the Ebro Observatory. Analyzing the temporal evolution of the absolute and normalized N-S asymmetry indices during 1910—1937, a cyclic behavior in which the dominant solar hemisphere changes systematically with a global period of 7.9±0.2 yr.
The tribunal is made up by Dr. Blai Sanhuja Parera, Dr. Xavier Vilasís Cardona and Dr. Josep Lluís Ballester Mortes.