Datasets of the solar quiet (Sq) and solar disturbed (SD) variations of the geomagnetic field at a midlatitudinal station in Europe obtained by different methods

Abstract

Here we present datasets of daily variation obtained from the geomagnetic field raw observations recorded at the Coimbra Magnetic Observatory (COI, Portugal) between 01.01.2007 and 31.12.2017, covering almost the entire solar cycle 24. Two methods were used to extract daily variability from the raw geomagnetic hourly data. The first method uses the so-called "geomagnetically quiet days" to calculate S-type variations as daily means resulting in the data sub-set named "IQD Sq and SD". The second method uses the principal component analysis (PCA) to decompose the original series into main variability modes. The first three modes produced by PCA and explaining up to 98% of the variability of the raw data are in the data sub-set named "PCA modes". Both methods allow to extract regular geomagnetic field variations related to daily variations (S-type variations) in the ionospheric dynamo region and some magnetospheric currents (e.g., field-aligned currents).

Principal Component Analysis As a Tool to Extract Sq Variation from the Geomagnetic Field Observations: Conditions of Applicability

“…Figure3shows examples of PC1, PC2 and PC3 together with Sq IQD for the X component. All PC1, PC2 and PC3 series as well as the Sq series can be found atMorozova et al (2021b). There are two main types of the shape of the Sq X variations obtained from the COI data:…”