Journal articles: 'Geomagnetic observatories'

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Schröder, W., K. H. Wiederkehr, and K. Schlegel. "Georg von Neumayer and geomagnetic research." History of Geo- and Space Sciences 1, no. 2 (2010): 77–87. http://dx.doi.org/10.5194/hgss-1-77-2010.

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Abstract. Neumayer was a prominent figure in the development of geophysics in the 19th century from a scientific as well as from an organisational point of view. In this paper we review and highlight his activities and efforts in geomagnetic research within five different aspects of geomagnetism: regional geomagnetic surveys, geomagnetic work in German naval observatories, geomagnetic investigations during the First Polar Year 1882/83, modifications of the Gaussian theory, and geomagnetic charts. In each field Neumayer was a researcher, a thinker, and a stimulating coordinator.

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Regi, Mauro, Paolo Bagiacchi, Domenico Di Mauro, Stefania Lepidi, and Lili Cafarella. "On the validation of K-index values at Italian geomagnetic observatories." Geoscientific Instrumentation, Methods and Data Systems 9, no. 1 (2020): 105–15. http://dx.doi.org/10.5194/gi-9-105-2020.

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Abstract. The local K index and the consequent global Kp index are well-established 3 h range indices used to characterize geomagnetic activity. The K index is one of the parameters that INTERMAGNET observatories can provide, and it has been widely used for several decades, although many other activity indices have been proposed in the meanwhile. The method for determining the K values has to be the same for all observatories. The INTERMAGNET consortium recommends the use of one of the four methods endorsed by the International Service of Geomagnetic Indices (ISGI) in close cooperation and agreement with the ad hoc working group of the International Association of Geomagnetism and Aeronomy (IAGA). INTERMAGNET provides the software code KASM, designed for an automatic calculation of the K index according to the adaptive smoothed method. K values should be independent of the local dynamic response, and therefore for their determination each observatory has its own specific scale regulated by the L9 lower limit, which represents the main input parameter for KASM. The determination of an appropriate L9 value for any geomagnetic observatory is then fundamental. In this work we statistically analyze the K values estimated by means of KASM code for the Italian geomagnetic observatories of Duronia (corrected geomagnetic latitude λ∼36∘ N) and Lampedusa (λ∼28∘ N) by comparing them with the German observatories of Wingst and Niemegk. Our comparative analysis is finalized to establish the best estimation of the L9 lower limit for these two stations. A comparison of L9 lower limits found for the Italian observatories with results from a previous empirical method was also applied and used to verify the consistency and reliability of our outcomes.

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Linthe, Hans-Joachim. "History of the Potsdam, Seddin and Niemegk geomagnetic observatories – Part 1: Potsdam." History of Geo- and Space Sciences 14, no. 1 (2023): 23–31. http://dx.doi.org/10.5194/hgss-14-23-2023.

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Abstract. The measurement series of the three geomagnetic observatories Potsdam, Seddin and Niemegk spans more than 130 years, starting in 1890. It is one of the longest, almost uninterrupted series of recordings of the Earth's magnetic field. Data users frequently emphasise the high quality of the data and their significance for geomagnetic base research. Very well known outstanding geomagnetism scientists, such as Max Eschenhagen, Adolf Schmidt, Julius Bartels, Gerhard Fanselau and Horst Wiese, directed the observatories during their existence. This paper describes the history of the Potsdam Observatory, which was in operation from 1890 until 1928.

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Lanzerotti, L. J., and A. D. Chave. "Geomagnetic observatories threatened again." Eos, Transactions American Geophysical Union 68, no. 22 (1987): 556. http://dx.doi.org/10.1029/eo068i022p00556-01.

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Lanzerotti, L. J., and A. D. Chave. "Geomagnetic observatories threatened again." Eos, Transactions American Geophysical Union 68, no. 22 (1987): 556. http://dx.doi.org/10.1029/eo068i022p00556-05.

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Lanzerotti, L. J. "On closing geomagnetic observatories." Eos, Transactions American Geophysical Union 67, no. 12 (1986): 145. http://dx.doi.org/10.1029/eo067i012p00145-02.

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Kaftan, V. I., and R. I. Krasnoperov. "Geodetic observations at geomagnetic observatories." Geomagnetism and Aeronomy 55, no. 1 (2015): 118–23. http://dx.doi.org/10.1134/s0016793215010065.

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Malaquias, Isabel, Emília Vaz Gomes, and Décio Martins. "The Genesis of Geomagnetic Observatories in Portugal." Earth Sciences History 24, no. 1 (2005): 113–26. http://dx.doi.org/10.17704/eshi.24.1.y7250t05306q7215.

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Interest in mapping not merely the heavens but also the lands, a special concern of modern civilizations, increased mainly at the end of the eighteenth and beginning of the nineteenth centuries. Although knowledge about geomagnetism was old, only in the nineteenth century was it possible to improve precision measurements of magnetic intensity. After Carl Friedrich Gauss (1777-1855) established an international Magnetic Union (Magnetische Verein) based in Göttingen in 1836, a network of magnetic observatories promoted a worldwide collaboration in order to get a deeper understanding of Earth's magnetism. While the participation of England, Russia, and the United States in this network is better known, Portugal also participated in this Union. This article aims to show how Portuguese institutions were influenced by the development of this branch of science and to detail their participation in the international geomagnetic network in the nineteenth century.

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Margiono, Relly, Christopher W. Turbitt, Ciarán D. Beggan, and Kathryn A. Whaler. "Production of definitive data from Indonesian geomagnetic observatories." Geoscientific Instrumentation, Methods and Data Systems 10, no. 2 (2021): 169–82. http://dx.doi.org/10.5194/gi-10-169-2021.

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Abstract. Measurement of the geomagnetic field in Indonesia is undertaken by the Meteorological, Climatological, and Geophysical Agency (BMKG). Routine activities at each observatory include the determination of declination, inclination, and total field using absolute and variation measurements. The oldest observatory is Tangerang (TNG), started in 1957, followed by Tuntungan (TUN) in 1980, Tondano (TND) in 1990, Pelabuhan Ratu (PLR) and Kupang (KPG) in 2000, and Jayapura (JAY) in 2012. One of the main obligations of a geomagnetic observatory is to produce final versions of data, released as definitive data, for each year and make them widely available both for scientific and non-scientific purposes, for example to the World Data Centre of Geomagnetism (WDC-G). Unfortunately, some Indonesian geomagnetic observatories do not share their data with the WDC-G and often have difficulty in producing definitive data. In addition, some more basic problems still exist, such as low-quality data due to anthropogenic or instrumental noise, a lack of data-processing knowledge, and limited observer training. In this study, we report on the production of definitive data from Indonesian observatories, and some recommendations are provided about how to improve the data quality. These methods and approaches are applicable to other institutes seeking to enhance their data quality and scientific utility, for example in main field modelling or space weather monitoring. The definitive data from the years 2010 to 2018 are now available in the WDC-G.

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Fujii, Ikuko, and Shingo Nagamachi. "History of Kakioka Magnetic Observatory." History of Geo- and Space Sciences 13, no. 2 (2022): 147–70. http://dx.doi.org/10.5194/hgss-13-147-2022.

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Abstract. Kakioka Magnetic Observatory (KMO) was founded in 1913 by the Central Meteorological Observatory (CMO, later the Japan Meteorological Agency) as a successor to Tokyo Magnetic Observatory. Kakioka was a village 70 km north of Tokyo and was selected to escape from tram noise in Tokyo. At first, it was an unstaffed observatory only for geomagnetic field observation. Then, the Great Kanto Earthquake in 1923 changed the fate of KMO because the earthquake severely damaged the CMO in Tokyo, and recording papers of KMO were lost. KMO was staffed in 1924 and was redesigned as an institute for geophysics rather than geomagnetism. KMO operated a variety of observations, such as the atmospheric electric field, the geoelectric field, the seismicity, the air temperature, the wind velocity, the sunspot and solar prominence as well as the geomagnetic field, by the 1940s. In addition, research activity flourished with the leadership of the first director, Shuichi Imamichi. After World War II was over in 1945, KMO formed a network of observatories in Japan by founding several branch observatories originally for geoelectric field observation. Two branch observatories at Memambetsu and Kanoya survived, with geomagnetic field observation added in the International Geophysical Year project (1957–1958). Efforts in development of instruments for geomagnetic absolute measurement and systems of high-sampling recordings in the 1950s to 1970s resulted in the development of the Kakioka Automatic Standard Magnetometer (KASMMER) system in 1972. KASMMER measured the geomagnetic field every 3 s at the highest standard in the world in digital form, giving 1 min digital values of the geomagnetic field available. This system has been updated, and the high-sampling technology was applied to geoelectric field observation and atmospheric electric field observation. Later, adding geomagnetic field observation at Chichijima in 1971, KMO established a unique electric and magnetic observation network at Kakioka, Memambetsu, Kanoya and Chichijima and provided precise and high-speed sampling data (1 min, 1 and 0.1 s values) by 2001. On the other hand, KMO gradually terminated or automated their observations and reduced their staff in the last several decades following the government's reform policy. The two branch observatories at Memambetsu and Kanoya were unstaffed in 2011, and the atmospheric electric field at Memambetsu was terminated at that time. The geoelectric field observations at Kakioka, Memambetsu and Kanoya were terminated in 2021 as well as the atmospheric electric field at Kakioka. KMO focuses on geomagnetic observation for now and puts efforts into total force observation at volcanoes and the digitization of historic analog data.

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Spivak, A. A., and S. A. Riabova. "Geomagnetic effect of earthquakes." Доклады Академии наук 488, no. 2 (2019): 197–201. http://dx.doi.org/10.31857/s0869-56524882197-201.

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Based on the results of instrumental observations carried out at a number of mid-latitude observatories of the INTERMAGNET network and at the Mikhnevo Geophysical Observatory of Institute of Geosphere Dynamics of Russian Academy of Sciences, it is shown that strong earthquakes are accompanied by increased variations of Earth’s magnetic field. In this case, the short-period stage (period ~ 0.5-0.8 min) and long-period stage (period ~ 5-20 min) of increased geomagnetic variations are clearly distinguished. The maximum amplitude of induced geomagnetic variations is 1.5-2 nT and 2- 4 nT, respectively, for short-period and long-period variations. A similar in morphology and almost synchronous nature of the induced geomagnetic disturbances at the observatories located at significantly different distances from the earthquake source is noted.

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Naaman, Sh, L. S. Alperovich, Sh Wdowinski, M. Hayakawa, and E. Calais. "Comparison of simultaneous variations of the ionospheric total electron content and geomagnetic field associated with strong earthquakes." Natural Hazards and Earth System Sciences 1, no. 1/2 (2001): 53–59. http://dx.doi.org/10.5194/nhess-1-53-2001.

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Abstract. In this paper, perturbations of the ionospheric Total Electron Content (TEC) are compared with geomagnetic oscillations. Comparison is made for a few selected periods, some during earthquakes in California and Japan and others at quiet periods in Israel and California. Anomalies in TEC were extracted using Global Positioning System (GPS) observations collected by GIL (GPS in Israel) and the California permanent GPS networks. Geomagnetic data were collected in some regions where geomagnetic observatories and the GPS network overlaps. Sensitivity of the GPS method and basic wave characteristics of the ionospheric TEC perturbations are discussed. We study temporal variations of ionospheric TEC structures with highest reasonable spatial resolution around 50 km. Our results show no detectable TEC disturbances caused by right-lateral strike-slip earthquakes with minor vertical displacement. However, geomagnetic observations obtained at two observatories located in the epicenter zone of a strong dip-slip earthquake (Kyuchu, M = 6.2, 26 March 1997) revealed geomagnetic disturbances occurred 6–7 h before the earthquake.

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Wu, Yingyan, Libo Liu, and Zhipeng Ren. "Equinoctial Asymmetry in Solar Quiet Fields along the 120° E Meridian Chain." Applied Sciences 11, no. 19 (2021): 9150. http://dx.doi.org/10.3390/app11199150.

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Equinoctial asymmetry of the range of the solar quiet day variation (Sq) of the horizontal geomagnetic field (H) has been found in some low latitude geomagnetic observatories. This study conducted an investigation of its latitude distribution and the relationship with the solar cycle by using the H field measurements from six observatories along the 120° E meridian chain in the years 1957–2013. Results illustrate a significant equinoctial asymmetry of the SqH range at all observatories. Three main features were identified. First, the signature of the equinoctial asymmetry of the SqH range is opposite for observatories located at the northern and southern sides of the Northern Hemisphere Sq current focus. It shows larger values around spring than autumn equinox at southern observatories, and the converse is seen at northern observatories. Second, the asymmetry increases with the distance from the Sq current focus, suggesting the stronger sensitivity of the distant observatories than observatories around the focus. The result of linear fitting presents a positive dependence of the asymmetry coefficient on geographic latitude, with a reversal of the asymmetry occurring at 28.1° N near the focus of the average Sq current. Third, there is no obvious dependence of the equinoctial asymmetry of the SqH range on solar activity, suggesting a possible cause from some regional factors related to the ionospheric dynamo process.

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Mandrikova, Oksana V., Igor S. Solovyev, Sergey Y. Khomutov, Vladimir V. Geppener, Dmitry M. Klionskiy, and Mikhail I. Bogachev. "Multiscale variation model and activity level estimation algorithm of the Earth's magnetic field based on wavelet packets." Annales Geophysicae 36, no. 5 (2018): 1207–25. http://dx.doi.org/10.5194/angeo-36-1207-2018.

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Abstract. We suggest a wavelet-based multiscale mathematical model of geomagnetic field variations. The model is particularly capable of reflecting the characteristic variation and local perturbations in the geomagnetic field during the periods of increased geomagnetic activity. Based on the model, we have designed numerical algorithms to identify the characteristic variation component as well as other components that represent different geomagnetic field activity. The substantial advantage of the designed algorithms is their fully automatic performance without any manual control. The algorithms are also suited for estimating and monitoring the activity level of the geomagnetic field at different magnetic observatories without any specific adjustment to their particular locations. The suggested approach has high temporal resolution reaching 1 min. This allows us to study the dynamics and spatiotemporal distribution of geomagnetic perturbations using data from ground-based observatories. Moreover, the suggested approach is particularly capable of discovering weak perturbations in the geomagnetic field, likely linked to the nonstationary impact of the solar wind plasma on the magnetosphere. The algorithms have been validated using the experimental data collected at the IKIR FEB RAS observatory network. Keywords. Magnetospheric physics (storms and substorms)

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Bhardwaj, S. K., and G. K. Rangarajan. "Geomagnetic Secular Variation at the Indian Observatories." Journal of geomagnetism and geoelectricity 49, no. 9 (1997): 1131–44. http://dx.doi.org/10.5636/jgg.49.1131.

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Lepidi, S., L. Cafarella, M. Pietrolungo, and D. Di Mauro. "Daily variation characteristics at polar geomagnetic observatories." Advances in Space Research 48, no. 3 (2011): 521–28. http://dx.doi.org/10.1016/j.asr.2011.03.039.

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Le Mouël, J. L., E. Blanter, and M. Shnirman. "The six-month line in geomagnetic long series." Annales Geophysicae 22, no. 3 (2004): 985–92. http://dx.doi.org/10.5194/angeo-22-985-2004.

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Abstract. Daily means of the horizontal components X (north) and Y (east) of the geomagnetic field are available in the form of long series (several tens of years). Nine observatories are used in the present study, whose series are among the longest. The amplitudes of the 6-month and 1-year periodic variations are estimated using a simple but original technique. A remarkably clear result emerges from the complexity of the geomagnetic data: the amplitude of the 6-month line presents, in all observatories, the same large variation (by a factor of 1.7) over the 1920–1990 time span, regular and quasi-sinusoidal. Nothing comparable comes out for the annual line. The 6-month line results from the modulation by an astronomical mechanism of a magnetospheric system of currents. As this latter mechanism is time invariant, the intensity of the system of currents itself must present the large variation observed on the 6-months variation amplitude. This variation presents some similarities with the one displayed by recent curves of reconstructed solar irradiance or the "Earth's temperature". Finally, the same analysis is applied to the aa magnetic index.Key words. Geomagnetism and paleomagnetism (time variations, diurnal to secular). Magnetospheric physics (current systems; polar cap phenomena)

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Sridharan, M., N. Gururajan, and A. M. S. Ramasamy. "Fuzzy clustering analysis to study geomagnetic coastal effects." Annales Geophysicae 23, no. 4 (2005): 1157–63. http://dx.doi.org/10.5194/angeo-23-1157-2005.

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Abstract. The utility of fuzzy set theory in cluster analysis and pattern recognition has been evolving since the mid 1960s, in conjunction with the emergence and evolution of computer technology. The classification of objects into categories is the subject of cluster analysis. The aim of this paper is to employ Fuzzy-clustering technique to examine the interrelationship of geomagnetic coastal and other effects at Indian observatories. Data from the observatories used for the present studies are from Alibag on the West Coast, Visakhapatnam and Pondicherry on the East Coast, Hyderabad and Nagpur as central inland stations which are located far from either of the coasts; all the above stations are free from the influence of the daytime equatorial electrojet. It has been found that Alibag and Pondicherry Observatories form a separate cluster showing anomalous variations in the vertical (Z)-component. H- and D-components form different clusters. The results are compared with the graphical method. Analytical technique and the results of Fuzzy-clustering analysis are discussed here.

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Pietrolungo, M., S. Lepidi, L. Cafarella, L. Santarelli, and D. Di Mauro. "Daily variation at three Antarctic geomagnetic observatories within the polar cap." Annales Geophysicae 26, no. 8 (2008): 2179–90. http://dx.doi.org/10.5194/angeo-26-2179-2008.

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Abstract. In this work we present a statistical analysis of the diurnal variation as observed at three Antarctic observatories located at different positions within the polar cap during the year 2006. Data used for the analysis are from the Italian geomagnetic observatory at Mario Zucchelli Station (formerly Terra Nova Bay, geographic latitude 74.7° S, corrected geomagnetic latitude 80.0° S), from the French-Italian observatory at Concordia Station (75.1° S, 88.9° S) and from the French observatory at Dumont D'Urville (66.7° S, 80.4° S), which are located in pairs at the same geographic and corrected geomagnetic latitude; such a position allows to distinguish whether the geographic or the geomagnetic reference system is better suitable to describe the observed phenomena at so high latitudes. The peculiarities of the daily variation as observed during this year and its relation with the observatory location and magnetospheric and interplanetary conditions were analysed. Data were also studied taking into account different Lloyd seasons. The results indicate that the 24-h variation is quite persistent, but its amplitude strongly depends on season and global geomagnetic activity: indeed, it almost vanishes during local winter for quiet geomagnetic conditions; this reduction is more evident at the stations closer to the geographic pole, where the solar radiation reduction during winter is more dramatic. The Interplanetary Magnetic Field orientation has been found to be important in that the north-south and the east-west components control the amplitude and the diurnal pattern of the variation, respectively.

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Worthington, E. William, and Jürgen Matzka. "U.S. Geological Survey experience with the residual absolutes method." Geoscientific Instrumentation, Methods and Data Systems 6, no. 2 (2017): 419–27. http://dx.doi.org/10.5194/gi-6-419-2017.

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Abstract. The U.S. Geological Survey (USGS) Geomagnetism Program has developed and tested the residual method of absolutes, with the assistance of the Danish Technical University's (DTU) Geomagnetism Program. Three years of testing were performed at College Magnetic Observatory (CMO), Fairbanks, Alaska, to compare the residual method with the null method. Results show that the two methods compare very well with each other and both sets of baseline data were used to process the 2015 definitive data. The residual method will be implemented at the other USGS high-latitude geomagnetic observatories in the summer of 2017 and 2018.

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Zhang, Suqin, Changhua Fu, Jianjun Wang, et al. "Rescue and quality control of historical geomagnetic measurement at Sheshan observatory, China." Earth System Science Data 14, no. 11 (2022): 5195–212. http://dx.doi.org/10.5194/essd-14-5195-2022.

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Abstract. The Sheshan Geomagnetic Observatory (International Association of Geomagnetism and Aeronomy (IAGA) code SSH), China was built in Xujiahui, Shanghai in 1874 and moved to Sheshan, Shanghai at the end of 1932. So far, the SSH has a history of nearly 150 years. It is one of the earliest geomagnetic observatories in China and one of the geomagnetic observatories with the longest history in the world. In this paper, we present the rescue and quality control (QC) of the historical data at the SSH from 1933 to 2019. The rescued data are the absolute hourly mean values (AHMVs) of declination (D), horizontal (H), and vertical (Z) components. Some of these data are paper-based records and some are stored in a floppy disk in BAS, DBF, MDB, and other file storage formats. After digitization and format transformation, we imported the data into the Toad database to achieve the unified data management. We performed statistics of completeness, visual analysis, outliers detects, and data correction on the stored data. We then conducted the consistency test of daily variation and secular variation (SV) by comparing the corrected data with the data of the reference observatory, and the computational data of the COV-OBS model, respectively. The consistency test reveals good agreement. However, the individual data should be used with caution because these data are suspicious values, but there is not any explanation or change registered in the available metadata and logbooks. Finally, we present examples of the datasets in discriminating geomagnetic jerks and study of storms. The digitized and quality-controlled AHMVs data are available at: https://doi.org/10.5281/zenodo.7005471 (Zhang et al., 2022).

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Lemperger, István, Judit Szendrői, Csongor Szabó, et al. "Geomagnetic observation system in the Széchenyi István Geophysical Observatory." Geophysical Observatory Reports 2020 (2021): 26–34. http://dx.doi.org/10.55855/gor2020.4.

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Geomagnetic and geoelectric registration has been continuously executed in SZIGO for more than six decades. The Observatory is a member of the global network of the geomagnetic observatories, the so-called INTERMAGNET (https://www.intermagnet.org). The geomagnetic observation system has recently been renewed in all of its components and the organically related geoelectric measurement system is going to be upgraded and improved, too. Present paper provides a short summary of the new geomagnetic observation system and introduces a few SSC events registered in the SZIGO from the last 12 months via the new observation station.

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Липко, Юрий, Yuriy Lipko, Александр Пашинин, et al. "Geomagnetic effects caused by rocket exhaust jets." Solar-Terrestrial Physics 2, no. 3 (2016): 43–55. http://dx.doi.org/10.12737/22284.

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In the space experiment Radar–Progress, we have made 33 series of measurements of geomagnetic variations during ignitions of engines of Progress cargo spacecraft in low Earth orbit. We used magneto-measuring complexes, installed at observatories of the Institute of Solar-Terrestrial Physics of Siberian Branch of the Russian Academy of Sciences, and magnetotelluric equipment of a mobile complex. We assumed that engine running can cause geomagnetic disturbances in field tubes crossed by the spacecraft. When analyzing experimental data, we took into account the following space weather factors: solar wind parameters, total daily mid-latitude geomagnetic activity index Kр, geomagnetic auroral electrojet index AE, global geomagnetic activity.

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Stuart, W. F. "Using commerce to fund Third World geomagnetic observatories." Eos, Transactions American Geophysical Union 72, no. 31 (1991): 332. http://dx.doi.org/10.1029/eo072i031p00332-02.

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SRINIVASAN, P. K., and N. SIVASANKARA SASTRI. "Direction of Rapid Geomagnetic changes at Indian observatories." MAUSAM 15, no. 1 (2022): 90–94. http://dx.doi.org/10.54302/mausam.v15i1.5524.

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Kuwashima, M. "Accuracy in geomagnetic measurements of Japanese magnetic observatories." Physics of the Earth and Planetary Interiors 59, no. 1-2 (1990): 104–11. http://dx.doi.org/10.1016/0031-9201(90)90215-j.

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Zhou, Jun-Cheng, Ke-Li Han, and Yue Lu. "The Beijing network of digital geomagnetic pulsation observatories." Acta Seismologica Sinica 7, no. 3 (1994): 489–94. http://dx.doi.org/10.1007/bf02650688.

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Rahim, Zain, and Abdul Salam Kumbher. "Solar daily variation at geomagnetic observatories in Pakistan." Journal of Atmospheric and Solar-Terrestrial Physics 140 (March 2016): 41–54. http://dx.doi.org/10.1016/j.jastp.2016.01.016.

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Borodin, Pavel, Jorge Brenes, Elias Daudi, et al. "INDIGO: Better Geomagnetic Observatories Where We Need Them." Data Science Journal 10 (2011): IAGA91—IAGA94. http://dx.doi.org/10.2481/dsj.iaga-15.

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Lauridsen, Emil Kring. "Development at Danish geomagnetic observatories in recent years." Deutsche Hydrographische Zeitschrift 41, no. 3-6 (1988): 131–44. http://dx.doi.org/10.1007/bf02225923.

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Vorobev, Andrei, Vyacheslav Pilipenko, Gulnara Vorobeva, and Olga Khristodulo. "Development and application of problem-oriented digital twins for magnetic observatories and variation stations." Information and Control Systems, no. 2 (April 29, 2021): 60–71. http://dx.doi.org/10.31799/1684-8853-2021-2-60-71.

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Introduction: Magnetic stations are one of the main tools for observing the geomagnetic field. However, gaps and anomalies in time series of geomagnetic data, which often exceed 30% of the number of recorded values, negatively affect the effectiveness of the implemented approach and complicate the application of mathematical tools which require that the information signal is continuous. Besides, the missing values add extra uncertainty in computer simulation of dynamic spatial distribution of geomagnetic variations and related parameters. Purpose: To develop a methodology for improving the efficiency of technical means for observing the geomagnetic field. Method: Creation of problem-oriented digital twins of magnetic stations, and their integration into the collection and preprocessing of geomagnetic data, in order to simulate the functioning of their physical prototypes with a certain accuracy. Results: Using Kilpisjärvi magnetic station (Finland) as an example, it is shown that the use of digital twins, whose information environment is made up of geomagnetic data from adjacent stations, can provide the opportunity for reconstruction (retrospective forecast) of geomagnetic variation parameters with a mean square error in the auroral zone of up to 11.5 nT. The integration of problem-oriented digital twins of magnetic stations into the processes of collecting and registering geomagnetic data can provide automatic identification and replacement of missing and abnormal values, increasing, due to the redundancy effect, the fault tolerance of the magnetic station as a data source object. For example, the digital twin of Kilpisjärvi station recovers 99.55% of annual information, and 86.73% of it has an error not exceeding 12 nT. Discussion: Due to the spatial anisotropy of geomagnetic field parameters, the error at the digital twin output will be different in each specific case, depending on the geographic location of the magnetic station, as well as on the number of the surrounding magnetic stations and the distance to them. However, this problem can be minimized by integrating geomagnetic data from satellites into the information environment of the digital twin. Practical relevance: The proposed methodology provides the opportunity for automated diagnostics of time series of geomagnetic data for outliers and anomalies, as well as restoration of missing values and identification of small-scale disturbances.

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Larocca, Patricia, M. A. Arecco, and M. Mora. "Wavelet-based Characterization of Seismicity and Geomagnetic Disturbances in the South Sandwich Microplate Area." Geofísica Internacional 60, no. 4 (2021): 320–32. http://dx.doi.org/10.22201/igeof.00167169p.2021.60.4.2119.

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This paper analyzes geomagnetic disturbances associated with seismic events in the northern transcurrent margin of the South Sandwich microplate and South American plate, with their epicenter at distances within 350 km from King Edward Point geomagnetic observatory on the archipelago of the Georgias del Sur islands. Geomagnetic field records measured over a one-year period in three observatories of the INTERMAGNET network near the area under study are examined. Anomalous variations in geomagnetic records can be detected within approximately 3 hours before the manifestation of seismic events with a magnitude above 4.4 Mw. Based on the analysis of the differences in horizontal field components among the observatories and the frequency spectrum of the geomagnetic field observations using the wavelet method, oscillations of several nT can be observed before an event, in addition to magnetic peaks with variable amplitude and duration. It is worth noting that, during the period of study, no severe ionospheric effects were recorded as this was a phase of low solar activity (solar cycle 24 minimum). The observation of these potential magnetic precursors suggests that there is a critical preparatory period in a region with geological faults related to the stress generated in the rocks before the built-up energy is released in the hypocenter area, within the lithosphere, which may predict the mechanical motion based on anomalous geomagnetic records.

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Valach, Fridrich, Magdaléna Váczyová, Peter Dolinský, and Melinda Vajkai. "Substitution for lost one-hour means of the geomagnetic elements for the first half of the 20-th century at the Hurbanovo Geomagnetic Observatory by means of neural networks." Contributions to Geophysics and Geodesy 43, no. 2 (2013): 125–40. http://dx.doi.org/10.2478/congeo-2013-0008.

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Abstract The existence of long-acting observatories by itself does not guarantee that their historical magnetograms are available or complete. In the archive of the Hurbanovo Geomagnetic Observatory (acronym HRB; geographical coordinates 47.86 ◦ N, 18.19 ◦ E), records of the geomagnetic field made on photo paper covering the period between the two World Wars were found for which the values of the baselines are unknown. We studied if a feed-forward neural network with one hidden layer can be used to supplement one-hour means of the geomagnetic elements D, H and Z of observatory HRB, using for this purpose the geomagnetic data of observatories Potsdam, Seddin and Niemegk (all of them being referenced to Niemegk). We focused our interest on the first half of the 20-th century. The neural-network model for element D proved to be applicable to substitute for the lost data of the magnetic declination at observatory HRB; however, the usability of the model for both elements H and Z turned out to be limited to a few years close to beginning or end of data gaps. Further we supplemented the time series of annual means of geomagnetic elements D, H and Z at observatory HRB with the model data.

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Love, J. J. "Long-term biases in geomagnetic <i>K</i> and <i>aa</i> indices." Annales Geophysicae 29, no. 8 (2011): 1365–75. http://dx.doi.org/10.5194/angeo-29-1365-2011.

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Abstract. Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0–2009.0, solar cycles 11–23. The K data show persistent biases, especially for high (low) K-activity levels at British (Australian) observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4.

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Kim, Jung-Hee, and Heon-Young Chang. "Possible Influence of the Solar Eclipse on the Global Geomagnetic Field." Proceedings of the International Astronomical Union 13, S335 (2017): 167–70. http://dx.doi.org/10.1017/s1743921317007219.

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AbstractWe investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories. We confirm that the effect of solar eclipse can be seen over an interval of 180 minutes centered at the time of maximum eclipse on a site of a geomagnetic observatory. It is found that the effect of the solar eclipse on the geomagnetic field becomes conspicuous as the magnitude of a solar eclipse becomes larger. The effect of solar eclipses is more evident in the second half of the path of Moon’s shadow. We also find that the effect can be overwhelmed, more sensitively by geomagnetic disturbances than by solar activity of solar cycle.

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Липко, Юрий, Yuriy Lipko, Александр Пашинин, et al. "Geomagnetic effects caused by rocket exhaust jets." Solnechno-Zemnaya Fizika 2, no. 3 (2016): 33–40. http://dx.doi.org/10.12737/19634.

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In the space experiment Radar–Progress, we have made 33 series of measurements of geomagnetic variations during ignitions of engines of Progress cargo spacecraft in low Earth orbit. We used magneto-measuring complexes, installed at observatories of the Institute of Solar-Terrestrial Physics of Siberian Branch of the Russian Academy of Sciences, and magnetotelluric equipment of a mobile complex. We assumed that engine running can cause geomagnetic disturbances in flux tubes crossed by the spacecraft. When analyzing experimental data, we took into account space weather factors: solar wind parameters, total daily mid-latitude geomagnetic activity index Kр, geomagnetic auroral electrojet index AE, global geomagnetic activity.  The empirical data we obtained indicate that 18 of the 33 series showed geomagnetic variations in various time ranges.

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Obiekezie, T. N., S. C. Obiadazie, and G. A. Agbo. "Day-to-Day Variability of H and Z Components of the Geomagnetic Field at the African Longitudes." ISRN Geophysics 2013 (August 29, 2013): 1–7. http://dx.doi.org/10.1155/2013/909258.

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The Day-to-day variability of the geomagnetic field elements at the African longitudes has been studied for the year 1987 using geomagnetic data obtained from four different African observatories. The analysis was carried out on solar quiet days using hourly values of the Horizontal, , and vertical, , geomagnetic field values. The results of this study confirm that Sq is a very changeable phenomenon, with a strong day-to-day variation. This day-to-day variation is seen to be superimposed on magnetic disturbances of a magnetospheric origin.

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Soffel, H. C. "History of the Munich–Maisach–Fürstenfeldbruck Geomagnetic Observatory." History of Geo- and Space Sciences 6, no. 2 (2015): 65–86. http://dx.doi.org/10.5194/hgss-6-65-2015.

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Abstract. The Munich–Maisach–Fürstenfeldbruck Geomagnetic Observatory is one of the observatories with the longest recordings of the geomagnetic field. It started with hourly measurements on 1 August 1840. The founder of the observatory in Munich was Johann von Lamont (1805–1879), the Director of the Royal Bavarian Astronomical Observatory. He had been stimulated to build his own observatory by the initiative of the Göttingen Magnetic Union founded in 1834 by Alexander von Humboldt (1769–1859) and Carl Friedrich Gauss (1777–1855). Before 1840 fewer than five observatories existed; the most prominent ones were those in London and Paris. At the beginning Lamont used equipment delivered by Gauss in Göttingen, but soon started to build instruments of his own design. Among them was a nonmagnetic theodolite which allowed precise geomagnetic measurements to be made also in the field. During the 1850s Lamont carried out geomagnetic surveys and produced geomagnetic maps for Germany and many other European countries. At the end of the nineteenth century accurate geomagnetic measurements in Munich became more and more disturbed by the magnetic stray fields from electric tramways and industry. During this period the quality of the data suffered and the measurements had to be interrupted several times. After a provisional solution in Maisach, a village 25 km west of Munich, a final solution could be found in the vicinity of the nearby city of Fürstenfeldbruck. Here the measurements started again on 1 January 1939. Since the 1980s the observatory has been part of INTERMAGNET, an organization providing almost real-time geomagnetic data of the highest quality.

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Santarelli, Lucia, Paolo Bagiacchi, Giovanni Benedetti, Domenico Di Mauro, and Stefania Lepidi. "A New Installation for Geomagnetic Field Monitoring at Talos Dome, a Remote Antarctic Site Away from Permanent Observatories." Remote Sensing 15, no. 2 (2023): 339. http://dx.doi.org/10.3390/rs15020339.

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An automatic geomagnetic station for monitoring the Earth’s magnetic field variations was installed in December 2020 at Talos Dome, a remote site on the Antarctic Plateau, about 300 km away from the permanent geomagnetic observatory at Mario Zucchelli Station (MZS). Designed and assembled at the laboratory of electronics of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome, this autonomous station is formed by a vector magnetometer specifically manufactured by Lviv Institute (Ukraine) for very low temperatures and a low-power system supplied by batteries charged by a wind generator and solar panel. Data, sampled at 1 Hz, are locally stored and can be downloaded once a year during the Antarctic summer expeditions. The goal was to integrate observatory data for better monitoring the geomagnetic field from an uncovered Antarctic area. In fact, it is well known that the distribution of geomagnetic observatories strongly favors the northern hemisphere, and each new instrumental installation in Antarctica should be considered as a useful attempt to balance the geomagnetic monitoring in the two hemispheres. The achieved goal was to obtain a long data series, keeping the station working even during the austral winter when the temperature can reach −60 °C; we recorded almost 11 months of data in one year and the station is still operating. Data from the new station, jointly with data from permanent observatories, improve the analysis of the magnetospheric dynamics and the ionosphere–magnetosphere coupling. Talos Dome, together with the Italian geomagnetic observatory at Mario Zucchelli Station and New Zealand geomagnetic observatory at Scott Base, constitutes a network along the 80°S geomagnetic parallel, which is interesting for studying the longitudinal propagation of geomagnetic signals of external origin. In this work we present the characteristics of the station and of the data it provides, with the aim of them for analysis in the framework of space weather.

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Duka, B., A. De Santis, M. Mandea, A. Isac, and E. Qamili. "Geomagnetic jerks characterization via spectral analysis." Solid Earth Discussions 4, no. 1 (2012): 131–72. http://dx.doi.org/10.5194/sed-4-131-2012.

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Abstract. In this study we have applied spectral techniques to analyze geomagnetic field time-series provided by observatories, and compared the results with those obtained from analogous analyses of synthetic data estimated from models. Then, an algorithm is here proposed to detect the geomagnetic jerks in time-series, mainly occurring in the Eastern component of the geomagnetic field. Applying such analysis to time-series generated from global models has allowed us to depict the most important space-time features of the geomagnetic jerks all over the globe, since the beginning of XXth century. Finally, the spherical harmonic power spectra of the third derivative of the main geomagnetic field has been computed from 1960 to 2002.5, bringing new insights to understanding the spatial evolution of these rapid changes of the geomagnetic field.

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Duka, B., A. De Santis, M. Mandea, A. Isac, and E. Qamili. "Geomagnetic jerks characterization via spectral analysis." Solid Earth 3, no. 1 (2012): 131–48. http://dx.doi.org/10.5194/se-3-131-2012.

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Abstract. In this study we have applied spectral techniques to analyze geomagnetic field time-series provided by observatories, and compared the results with those obtained from analogous analyses of synthetic data estimated from models. Then, an algorithm is here proposed to detect the geomagnetic jerks in time-series, mainly occurring in the eastern component of the geomagnetic field. Applying such analysis to time-series generated from global models has allowed us to depict the most important space-time features of the geomagnetic jerks all over the globe, since the beginning of XXth century. Finally, the spherical harmonic power spectrum of the third derivative of the main geomagnetic field has been computed from 1960 to 2002.5, bringing new insights to understand the spatial evolution of these rapid changes of the geomagnetic field.

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Di Mauro, Domenico, Mauro Regi, Stefania Lepidi, et al. "Geomagnetic Activity at Lampedusa Island: Characterization and Comparison with the Other Italian Observatories, Also in Response to Space Weather Events." Remote Sensing 13, no. 16 (2021): 3111. http://dx.doi.org/10.3390/rs13163111.

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Regular automatic recordings of the time series of the magnetic field, together with routine manual absolute measurements for establishing dynamic baselines at Lampedusa Island—south of Sicily—Italy (geographic coordinates 35°31′N; 12°32′E, altitude 33 m a.s.l.), show a signature of very low electromagnetic noise. The observatory (provisional IAGA code: LMP) lays inside a restricted and remote wildlife reserve, far away from the built-up and active areas of the island, which at present is the southernmost location of the European territory for such observations. The availability of high-quality data from such site, whose survey started in 2005, is valuable for filling the spatial gap due to the lack of observatories in the whole south Mediterranean and North African sectors. We compare observations at Lampedusa, in both time and frequency domains, with those at the other Italian observatories (Castello Tesino and Duronia-L’Aquila), operating since the 1960s of last century, allowing us to report even the secular variation. Using data recorded in the last few years, we investigate higher frequency variations (from diurnal to Pc3-4 pulsations) in order to magnetically characterize the Italian territory and the local response to external forcing. In particular, we present a characterization in terms of diurnal variation and its seasonal dependence for the three observatories. This latter feature is in good agreement with a geomagnetic Sq-model, leading us to speculate about the position of the north Sq-current system vortex and its seasonal displacement with respect to the geographic positions of the observatories. We also study the geomagnetic individual response to intense space weather events by performing Superposed Epoch Analysis (SEA), with an ad-hoc significance test. Magnetic responses in the Ultra Low Frequency range (ULF) from spectral, local Signal-to-Noise Ratio (SNR) analyses under different local time, and polarization rates are computed. These latter studies lead us to search for possible signatures of magnetic field line resonances during intense space weather events, using cross-phase multi-observatory analysis, revealing the promising detection capability of such technique even at low latitudes. The geomagnetic observatories prove to be important points of observation for space weather events occurring at different spatial and time scales, originating in both upstream and ionospheric regions, here analyzed by several well-established methodologies and techniques. The quiet environmental site of LMP, providing high-quality geomagnetic data, allows us such investigations even at inner Earth’s magnetospheric shell.

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Wang, Xiao Mao. "Study on Variation Rate Characters of Mid-to-Low Latitude Area Geomagnetic Field during Geomagnetic Storms." Applied Mechanics and Materials 448-453 (October 2013): 2125–31. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.2125.

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Geomagnetic field changes acutely during geomagnetic storms. According to Faraday's law of electromagnetic induction, the change of the geomagnetic field produces geomagnetically induced current (GIC) in power grid, which directly damages the power equipment and threatens safe operation of power grid. The more dramatically geomagnetic field changes, the bigger geomagnetically induced current in power grid becomes, and thus, the greater harm it brings to power grid. In this paper, based on the H and D components of recent geomagnetic storm data measured by several mid-to-low latitude geomagnetic observatories, the variation law of the amplitude of north-south and east-west geomagnetic component change rate (dX/dt and dY/dt) pulse with geomagnetic latitude was analyzed when geomagnetic field changed very severely. Finally, the possibilities of power grid in different direction affected by GIC with the change of latitude were discussed. The analysis results will contribute to the evaluation, measurement and control of GIC in Chinese current and future power grid.

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Conesa, Jorge. "Relationship between Isolated Sleep Paralysis and Geomagnetic Influences: A Case Study." Perceptual and Motor Skills 80, no. 3_suppl (1995): 1263–73. http://dx.doi.org/10.2466/pms.1995.80.3c.1263.

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This preliminary report, of a longitudinal study, looks at the relationship between geomagnetic activity and the incidence of isolated sleep paralysis over a 23.5-mo. period. The author, who has frequently and for the last 24 years experienced isolated sleep paralysis was the subject. In addition, incidence of lucid dreaming, vivid dreams, and total dream frequency were looked at with respect to geomagnetic activity. The data were in the form of dream-recall frequency recorded in a diary. These frequency data were correlated with geomagnetic activity k-index values obtained from two observatories. A significant correlation was obtained between periods of local geomagnetic activity and the incidence of isolated sleep paralysis. Specifically, periods of relatively quiet geomagnetic activity were significantly associated with an increased incidence of episodes.

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Le Mouël, J. L., E. Blanter, A. Chulliat, and M. Shnirman. "On the semiannual and annual variations of geomagnetic activity and components." Annales Geophysicae 22, no. 10 (2004): 3583–88. http://dx.doi.org/10.5194/angeo-22-3583-2004.

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Abstract. The semiannual and annual lines in a long series of magnetic observatories daily values, as well as in the aa-activity index series, are investigated. For both periods, amplitudes and phases of the lines corresponding to the different series present grossly common variations on decadal time scales; relative phases and amplitude ratios between the observatories change with the same time constants. The results are briefly discussed with regards to commonly received theories of the semiannual variation of magnetic activity, and some possible mechanisms for the observed geographical variability are suggested.

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Sumaruk, Yu P., V. I. Starostenko, and O. V. Legostaeva. "Geomagnetic observatories of Ukraine in the Global Network INTERMAGNET." Russian Journal of Earth Sciences 12, no. 2 (2011): 1–12. http://dx.doi.org/10.2205/2011es000506.

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Stănică, Dragoș Armand, and Dumitru Stănică. "ULF Pre-Seismic Geomagnetic Anomalous Signal Related to Mw8.1 Offshore Chiapas Earthquake, Mexico on 8 September 2017." Entropy 21, no. 1 (2019): 29. http://dx.doi.org/10.3390/e21010029.

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In the last decade, the real time ground–based geomagnetic observations realized in correlation with the Vrancea seismicity in Romania, together with supplementary studies related to some earthquakes (Mw9.0 Tohoku, Japan on 11 March 2011 and Mw8.3 Coquimbo, Chile on 16 September 2015), enlarged our knowledge about the relationship between the pre-seismic anomalous phenomena and the final stage of the earthquake nucleation. To identify possible ultra-low-frequency (ULF) geomagnetic signals prior to the onset of an Mw8.1 earthquake, we retroactively analyzed the data collected on the interval 1 August–16 September 2017 at the Geomagnetic Observatories in Teoloyucan (TEO), Mexico and Tucson (TUC) USA, with the last taken as a reference. Daily mean distributions of the polarization parameter BPOL (geomagnetic polarization parameter) and standard deviation are obtained for both observatories using a fast Fourier transform (FFT) band-pass filtering in the ULF range (0.001–0.083 Hz). Further on, we investigated the singularity of the pre-seismic signal associated with an Mw8.1 earthquake and applied a statistical analysis based on a standardized random variable equation; results are presented as BPOL* time series on the interval 1–26 September. Finally, the hourly mean distribution, obtained as difference BPOL (TUC-TEO) on the interval 7–9 September emphasizes an anomalous signal with five hours before the onset of the Mw8.1 earthquake.

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YACOB, A., and K. B. KHANNA. "Geomagnetic Sq Variations and Parameters of the Indian Electrojet for 1958, 1959." MAUSAM 14, no. 4 (2022): 470–77. http://dx.doi.org/10.54302/mausam.v14i4.5498.

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Geomagnetic Sq variations at Trivandrum, Annamalainagar (both close to the magnetic equator) and Alibag are examined for the different seasons for the year 1958 and 1959. The ranges in H for the observatories close to the magnetic equator are as usual very large. Maximum ranges in H and Z occur in the equinoctial months while maximum range in D occurs during the summer. Other characteristics of the variations are pointed out, especially the anomalous nature of Sq (Z) at Trivandrum and Annamalainagar. Using the magnitudes of Sq (H) at the three observatories for the periods April to August (a period during which the solar noon-znith angle varies through about 20 for all the three observatories), estimates of the parameters of the Indian electrojet are made. The half-width of the electrojet is found to be nearly 300 km. The total current strength in the electrojet is about 148 A/km or 60,000 A/degree latitude. The factor by which the normal Sq current strength is intensified at the magnetic equator is found to be 2.4.

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DE SANTIS, A., D. BARRACLOUGH, and R. TOZZI. "NONLINEAR VARIABILITY IN THE GEOMAGNETIC SECULAR VARIATION OF THE LAST 150 YEARS." Fractals 10, no. 03 (2002): 297–303. http://dx.doi.org/10.1142/s0218348x02001336.

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A nonlinear forecasting analysis has been applied to the secular variation of the three-component annual means of 14 observatories, unevenly distributed over the Earth's surface (12 in the northern and 2 in the southern hemisphere) and spanning the last 150 years. All results were in agreement, either in terms of possible evidence of chaos (as opposed to the hypothesis of white or colored noise), or in terms of the Kolmogorov entropy, confirming previous results obtained with only three European observatories, i.e. it is practically impossible to predict the secular variation of the geomagnetic field more than six years into the future.

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He, Yufei, Xudong Zhao, Jianjun Wang, et al. "The operator difference in absolute geomagnetic measurements." Geoscientific Instrumentation, Methods and Data Systems 8, no. 1 (2019): 21–27. http://dx.doi.org/10.5194/gi-8-21-2019.

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Abstract. Absolute geomagnetic measurement is very important at geomagnetic observatories. It plays a decisive role in data quality control and instrument calibration. As absolute geomagnetic measurements from modern fluxgate theodolite instruments have high precision, usually within 1 arcsec, the measurement results are susceptible to external factors. The operator difference is one of these factors and has become an important consideration that can not be ignored with respect to measurement results. Therefore, an experiment was designed in order to estimate the operator difference. Six fluxgate theodolites were used and six observers who were proficient in absolute measurements were invited to participate. The observers took turns making absolute geomagnetic measurements, and the operator difference between the observers for each instrument was computed by comparing baseline values using statistical methods.

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Journal articles on the topic 'Geomagnetic observatories'

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