Characteristics of solar diurnal variations: a case study based on records from the ground magnetic observatory at Vassouras, Brazil

TL;DR

This study analyzes ground magnetic data to understand solar diurnal variations, revealing latitudinal, seasonal, and hemispheric differences influenced by geomagnetic and atmospheric factors.

Contribution

Introduces a new scale correlation approach and wavelet algorithm to analyze magnetogram data with gaps, revealing spatial and seasonal effects on diurnal variations.

Findings

Latitudinal dependence of magnetic variations affected by season and solar activity

Hemispheric asymmetry observed during solstices in magnetic responses

Disparities at similar latitudes during equinoxes

Abstract

The horizontal component amplitudes of magnetograms recorded by ground-based observatories of the INTERMAGNET network have been used to analyze the global pattern variance of the solar diurnal variations. Those kinds of data present gaps in records and consequently we explore them via a time-frequency gapped wavelet algorithm. We propose a new approach to analyze magnetograms based on scale correlation. The results show that the magnetic records have a latitudinal dependence affected by the season of year and by the level of solar activity. We have found a disparity on the latitudinal response at Southern and Northern Hemispheres during solstices, which is expected due to the asymmetry of the Sq field. On the other hand at equinoxes, records from stations located at approximately the same latitude but at different longitudes presented peculiar dissimilarities. The achieved results suggest that quiet day patterns and the physical processes involved in their formation are strongly affected by: the conductivity of the E-region, the geomagnetic field intensity and its configuration, and the thermospheric winds.