The system for the preparation of quasi-definitivedata of the INTERMAGNET standard is described. Unlike the final data, which was prepared no earlier than 1 year after the measurement, the data provided with the described system are available 1 day after the last series of absolute observations. Quasi-definitivedata are used to model fast variations in the main magnetic field of the Earth and to calculate indices of geomagnetic activity. The quality of the data obtained from a comparison of the approved final INTERMAGNET data and the data from the World Magnetic Model (WMM) and International Geomagnetic Reference Field (IGRF) model is analyzed. The quality of the quasi-definitive data obtained by the proposed method of automated algorithms is shown to be comparable to the quality provided by the traditional approaches to the preparation of the final INTERMAGNET standard data.

Since June 2012 the Saint Petersburg magnetic observatory is being developed and maintained by two institutions of the Russian Academy of Sciences (RAS) – the Geophysical Center of RAS (GC RAS) and the Saint Petersburg branch of the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of RAS (IZMIRAN SPb). On 29 April 2016 the application of the Saint Petersburg observatory (IAGA code SPG) for introduction into the INTERMAGNET network was accepted after approval by the experts of the first definitive dataset over 2015, produced by the GC RAS, and on 9 June 2016 the SPG observatory was officially certified. One of the oldest series of magnetic observations, originating in 1834, was resumed in the 21st century, meeting the highest quality standards and all modern technical requirements. In this paper a brief historical and scientific background of the SPG observatory foundation and development is given, the stages of its renovation and upgrade in the 21st century are described, and information on its current state is provided. The first results of the observatory functioning are discussed and geomagnetic variations registered at the SPG observatory are assessed and compared with geomagnetic data from the INTERMAGNET observatories located in the same region.

High-quality geomagnetic measurements are widely used in both fundamental research of the magnetic field and numerous industrial applications. However, vector data measured by fluxgate sensors show a dependency on temperature due to sensitive coil core material and components of the sensor electronics. Here, we propose a new method for detecting and eliminating temperature dependence in magnetic observatory data. The method is designed to correct temperature drifts in variation vector magnetometer measurements when preparing quasi-definitive data according to an INTERMAGNET standard. A special feature of the method is the semi-automatic adjustment of localization intervals for temperature correction, which prevents boundary jumps and discontinuities in the course of sequential data processing over long intervals. The conservative nature of the approach implies the minimization of the original data amount subjected to correction. The described method is successfully applied in the routine monthly preparation of quasi-definitive data of the Saint Petersburg Observatory (IAGA-code SPG) and can be efficiently introduced at other magnetic observatories worldwide.

We present candidate models for the 14th generation of the International Geomagnetic Reference Field (IGRF-14), specifically the Definitive Geomagnetic Reference Field (DGRF) for epoch 2020.0 and the IGRF for epoch 2025.0. These models were developed using high-quality magnetic measurements from the European Space Agency’s Swarm satellite mission, including data from three low-Earth orbiting satellites equipped with Absolute Scalar Magnetometers and Vector Field Magnetometers. These models are first GC RAS candidates in the IGRF series, where we aim on methodological clarity and incremental innovation, and are part of the CAMPUS project, which is devoted to the construction of a series of Earth’s magnetic field models. Our methodology employs rigorous data selection criteria to minimize contamination from external sources and with strict scalar-vector consistency constraints. The internal magnetic field is parameterized using spherical harmonic functions up to degree 13, with coefficients determined through a two-stage inversion process involving linear inversion of vector measurements followed by nonlinear refinement including absolute scalar intensity data. For the DGRF 2020 model, we utilized data collected between January 2019 and December 2020, while the IGRF 2025 model incorporates measurements from January 2023 to September 2024. Comparison between the models indicates changes in field structure over the 5-year interval, particularly in the South Atlantic Anomaly (SAA) region. These candidate models effectively capture the main features of Earth’s core-generated magnetic field and are consistent with long-term trends observed in previous IGRF generations, contributing to the collective scientific effort to maintain accurate descriptions of Earth’s magnetic field. Graphical Abstract

Highly accurate observations of the Earth’s total magnetic field vector promptly derived from the data recorded at the “St. Petersburg” (Leningrad oblast) and “Klimovskaya” (Arkhangelsk oblast) magnetic observatories are studied. It is shown that such data can be used for detecting geomagnetic jerks in secular variation records with a minimum time delay, which is difficult using the most recent models of the Earth’s core magnetic field. Based on the data over 2015–2022, we identify two jerks of 2017 and 2020, which fit well into the three-year quasi-periodicity observed since the beginning of the study of the rapid variations of the core field. The result confirms the hypothesis of the wave nature of the underlying processes in the liquid core.

Modern satellite positioning and navigation technologies are not applicable in specific areas such as the exploration of oil and gas deposits by means of directional drilling techniques. Here, we can rely solely on natural geophysical fields, such as the Earth’s magnetic field. The precise underground navigation of borehole drilling instruments requires a seamless, near-real-time access to operational geomagnetic data. This paper describes the MAGNUS BD hardware-software system, deployed at the Geophysical Center of the Russian Academy of Sciences, that provides the efficient accumulation, storage, and processing of geomagnetic data. This system, based on the Big Data (BD) technology, is a modern successor of the MAGNUS processing software complex developed in 2016. MAGNUS BD represents one of the first cases of the BD technology’s application to geomagnetic data. Its implementation provided a significant increase in the speed of information processing and allowed for the use of high-frequency geomagnetic satellite data and expanding the overall functionality of the system. During the MAGNUS BD system’s deployment on a physically separate dedicated cluster, the existing classical database (DB) was migrated to the Arenadata database with full preservation of its functionality. This paper gives a brief analysis of the current problems of directional drilling geomagnetic support and outlines the possible solutions using the MAGNUS BD system.