scholarly journals Datasets of the solar quiet (Sq) and solar disturbed (SD) variations of the geomagnetic field from the mid latitudinal Magnetic Observatory of Coimbra (Portugal) obtained by different methods

Data in Brief ◽  
2021 ◽  
pp. 107174
Author(s):  
Anna Morozova ◽  
Rania Rebbah ◽  
Paulo Ribeiro
Keyword(s):  
Geomagnetic Field ◽  
Magnetic Observatory

scholarly journals Investigation of Regional Geomagnetic Field Modelling in Indonesia

2021 ◽  
Author(s):  
Yosi Setiawan
Keyword(s):  
Basis Function ◽  
Geomagnetic Field ◽  
Modelling Technique ◽  
Magnetic Observatory ◽  
Observation Data ◽  
Spherical Cap ◽  
B Splines ◽  
Half Angle ◽  
Geomagnetic Field Models ◽  
Geomagnetic Observation

<p>This thesis deals with the application of the Spherical Cap Harmonic Analysis (SCHA) modelling technique to obtain geomagnetic field models for Indonesia, which have better resolution and accuracy than the International Geomagnetic Reference Field (IGRF). B-splines basis function and autoregressive forecasting are applied to improve estimates of secular variation and its forecast over the Indonesian region. The modelling technique is applied to geomagnetic observation data compiled from 68 geomagnetic repeat stations in Indonesia covering the period 1985 - 2015 from BMKG (Badan Meteorologi Klimatologi dan Geofisika / Agency for Meteorology, Climatology, and Geophysics) Indonesia, definitive data from five BMKG geomagnetic observatories and 13 INTERMAGNET (The International Real-Time Magnetic Observatory Network) observatories. Synthetic cartesian X, Y, and Z components at sea level at 17 fixed locations, calculated from IGRF-13, are also used. The area covered by the models in this thesis is the Indonesian region with a spherical cap half-angle of 30° and with the coordinate of the spherical cap pole at 122°E and 3°S. From statistical analysis and comparison with the IGRF, the SCHA model with index k = 7 is considered as the best SCHA model, both in resolution and accuracy. Compared with the root mean square deviation (RMSD) of the IGRF model, the RMSD of the SCHA model with index k = 7 is lower by 28 nT, 11 nT, and 34 nT for X, Y, and Z components, respectively. A model from interpolation of the SCHA with index k = 7 using the B-splines basis function for the year 1985.5 – 2015.5 shows that the SCHA model gives better results than the IGRF. The forecasting calculation for the year 2015.5 – 2020.5 suggests that the autoregressive order 3 of the SCHA with index k = 7 gives better results than the forecasting of the IGRF model, especially in the X, Z, and F components. However, in the Y component, the IGRF is still better than the SCHA model. The RMSD of the forecasted SCHA model is 154.92 nT, 200.87 nT, 104.39 nT, and 135.81 nT for X, Y, Z, and F components, respectively, while the RMSD of the IGRF model is 172.62 nT, 95.52 nT, 117.55 nT, and 162.38 nT for X, Y, Z, and F components. Thus, the forecasted SCHA model is suitable for data reduction of geomagnetic surveys in the Indonesian region but not preferable for navigation.</p>

scholarly journals Correction of artificial jumps in the historical geomagnetic measurements of Coimbra Observatory, Portugal

2014 ◽  
Vol 32 (1) ◽  
pp. 19-40 ◽  
Author(s):  
A. L. Morozova ◽  
P. Ribeiro ◽  
M. A. Pais
Keyword(s):  
Geomagnetic Field ◽  
Visual Analysis ◽  
Statistical Tests ◽  
Time Derivative ◽  
Liquid Core ◽  
Homogeneity Test ◽  
Magnetic Observatory ◽  
K Index ◽  
Standard Normal Homogeneity Test ◽  
Geomagnetic Measurements

Abstract. The Coimbra Magnetic Observatory (International Association of Geomagnetism and Aeronomy code COI) in Portugal has a long history of observation of the geomagnetic field, spanning almost 150 yr since the first geomagnetic measurements in 1866. These long instrumental geomagnetic records provide very important information about variability of geomagnetic elements and indices, their trends and cycles, and can be used to improve our knowledge on the sources that drive variations of the geomagnetic field: liquid core dynamics (internal) and solar forcing (external). However, during the long life of the Coimbra Observatory, some inevitable changes in station location, instrument's park and electromagnetic environment have taken place. These changes affected the quality of the data collected at COI causing breaks and jumps in the series of geomagnetic field components and local K index. Clearly, these inhomogeneities, typically shift-like (step-like) or trend-like, have to be corrected or, at least, minimized in order for the data to be used in scientific studies or to be submitted to international databases. In this study, the series of local K index and declination of the geomagnetic field are analysed: the former because it allows direct application of standard homogenization methods and the latter because it is the longest continuous series produced at COI. For the homogenization, visual and statistical tests (e.g. standard normal homogeneity test) have been applied directly to the local geomagnetic K index series (from 1951 to 2012). The homogenization of the monthly averages of declination (from 1867 to 2012) has been done using visual analysis and statistical tests applied to the time series of the first differences of declination values, as an approximation to the first time derivative. This allowed not only estimating the level of inhomogeneity of the studied series but also detecting the highly probable homogeneity break points. These points have been cross-checked with the metadata, and the COI series have been compared with reference series from the nearest geomagnetic stations and, in the case of declination series, from the recent geomagnetic field model COV-OBS to set up the required correction factors. As a result, the homogenized series measured in COI are considered to be essentially free of artificial shifts starting from the second half of the 20th century, and ready to be used by the scientific community.

scholarly journals Father Secchi and the first Italian magnetic observatory

2012 ◽  
Vol 3 (1) ◽  
pp. 33-45 ◽  
Author(s):  
N. Ptitsyna ◽  
A. Altamore
Keyword(s):  
Geomagnetic Field ◽  
Early Years ◽  
Magnetic Observatory ◽  
Systematic Monitoring ◽  
The Creation ◽  
The Church ◽  
Scientific Fields

Abstract. The first permanent magnetic observatory in Italy was built in 1858 by Pietro Angelo Secchi, a Jesuit priest who made significant contributions in a wide variety of scientific fields, ranging from astronomy to astrophysics and meteorology. In this paper we consider his studies in geomagnetism, which have never been adequately addressed in the literature. We mainly focus on the creation of the magnetic observatory on the roof of the church of Sant'Ignazio, adjacent to the pontifical university, known as the Collegio Romano. From 1859 onwards, systematic monitoring of the geomagnetic field was conducted in the Collegio Romano Observatory, for long the only one of its kind in Italy. We also look at the magnetic instruments installed in the observatory, which were the most advanced for the time, as well as scientific studies conducted there in its early years.

scholarly journals Investigation of Regional Geomagnetic Field Modelling in Indonesia

2021 ◽  
Author(s):  
Yosi Setiawan
Keyword(s):  
Basis Function ◽  
Geomagnetic Field ◽  
Modelling Technique ◽  
Magnetic Observatory ◽  
Observation Data ◽  
Spherical Cap ◽  
B Splines ◽  
Half Angle ◽  
Geomagnetic Field Models ◽  
Geomagnetic Observation

<p>This thesis deals with the application of the Spherical Cap Harmonic Analysis (SCHA) modelling technique to obtain geomagnetic field models for Indonesia, which have better resolution and accuracy than the International Geomagnetic Reference Field (IGRF). B-splines basis function and autoregressive forecasting are applied to improve estimates of secular variation and its forecast over the Indonesian region. The modelling technique is applied to geomagnetic observation data compiled from 68 geomagnetic repeat stations in Indonesia covering the period 1985 - 2015 from BMKG (Badan Meteorologi Klimatologi dan Geofisika / Agency for Meteorology, Climatology, and Geophysics) Indonesia, definitive data from five BMKG geomagnetic observatories and 13 INTERMAGNET (The International Real-Time Magnetic Observatory Network) observatories. Synthetic cartesian X, Y, and Z components at sea level at 17 fixed locations, calculated from IGRF-13, are also used. The area covered by the models in this thesis is the Indonesian region with a spherical cap half-angle of 30° and with the coordinate of the spherical cap pole at 122°E and 3°S. From statistical analysis and comparison with the IGRF, the SCHA model with index k = 7 is considered as the best SCHA model, both in resolution and accuracy. Compared with the root mean square deviation (RMSD) of the IGRF model, the RMSD of the SCHA model with index k = 7 is lower by 28 nT, 11 nT, and 34 nT for X, Y, and Z components, respectively. A model from interpolation of the SCHA with index k = 7 using the B-splines basis function for the year 1985.5 – 2015.5 shows that the SCHA model gives better results than the IGRF. The forecasting calculation for the year 2015.5 – 2020.5 suggests that the autoregressive order 3 of the SCHA with index k = 7 gives better results than the forecasting of the IGRF model, especially in the X, Z, and F components. However, in the Y component, the IGRF is still better than the SCHA model. The RMSD of the forecasted SCHA model is 154.92 nT, 200.87 nT, 104.39 nT, and 135.81 nT for X, Y, Z, and F components, respectively, while the RMSD of the IGRF model is 172.62 nT, 95.52 nT, 117.55 nT, and 162.38 nT for X, Y, Z, and F components. Thus, the forecasted SCHA model is suitable for data reduction of geomagnetic surveys in the Indonesian region but not preferable for navigation.</p>

scholarly journals Homogenization of the historical series from the Coimbra Magnetic Observatory, Portugal

2020 ◽  
Author(s):  
Anna L. Morozova ◽  
Paulo Ribeiro ◽  
M. Alexandra Pais
Keyword(s):  
20Th Century ◽  
Geomagnetic Field ◽  
Original Data ◽  
Magnetic Observatory ◽  
Time Interval ◽  
Historical Series ◽  
Long Lifetime ◽  
Continue Work ◽  
Artificial Changes ◽  
Almost Continuous

Abstract. The Coimbra Magnetic Observatory (COI), Portugal, established in 1866, provides almost continuous records of the geomagnetic field elements for more than 150 years. However, during its long lifetime inevitable changes of the instruments, measurement procedures and even re-location of the Observatory took place. In our previous work (Morozova et al., 2014) we performed homogenization – elimination of the artificial changes – of the measured declination series (D) for the period from 1866 to 2006. In this paper we continue work applying homogenization procedures to the measured series of the absolute monthly values of the horizontal (H, 1866–2006) vertical (Z, 1951–2006) and inclination components (I, 1866–1941). After homogenization of all measured series for the 1866-2006 time interval we performed the homogenization of the series of all geomagnetic field elements (X, Y, Z, H, D, I and F) to the level of epoch 2015. Since all series except D have a gap of about 10 years long in the middle of the 20th century, splitting each of them into two, the homogenization to the level of 2015 was done only for the series available after 1951 (with D series homogenized for the whole time interval 1866–2015). The COI geomagnetic field elements are available via the following addresses: COI original data – https://doi.org/10.5281/zenodo.4122066 (Ribeiro et al, 2020); COI homogenized data – https://doi.org/10.5281/zenodo.4122289 (Morozova et al, 2020).

scholarly journals FEATURES OF IONOSPHERIC EFFECTS FROM THE PARTIAL SOLAR ECLIPSE OVER THE CITY OF KHARKIV ON 10 JUNE 2021

2021 ◽  
Vol 26 (4) ◽  
pp. 326-343
Author(s):  
L. F. Chernogor ◽  
◽  
K. P. Garmash ◽  
Y. H. Zhdanko ◽  
S. G. Leus ◽  
...  
Keyword(s):  
Frequency Shift ◽  
Solar Eclipse ◽  
Geomagnetic Field ◽  
Doppler Frequency ◽  
Doppler Frequency Shift ◽  
Wave Activity ◽  
Dynamic Processes ◽  
Magnetic Observatory ◽  
Atmospheric Gravity ◽  
The City

Purpose: Solar eclipses pertain to high-energy sources of disturbance in the subsystems of the Sun–interplanetary-medium–magnetosphere–ionosphere–atmosphere–Earth and the Earth–atmosphere–ionosphere–magnetosphere systems. During the solar eclipse, the coupling between the subsystems in these systems activates, and the parameters of the dynamic processes become disturbed. Investigation of these processes contributes to understanding of the structure and dynamics of the subsystems. The ionospheric response to the solar eclipse depends on the season, local time, magnitude of the solar eclipse, phase of the solar cycle, the observation site, the state of space weather, etc. Therefore, the study of the effects, which each new solar eclipse has on the ionosphere remains an urgent geophysics and radio physics problem. The purpose of this paper is to describe the radio wave characteristics and ionospheric parameters, which accompanied the partial solar eclipse of 10 June 2021 over the City of Kharkiv. Design/methodology/approach: To make observations, the means of the HF Doppler measurements at vertical and oblique incidence available at the V. N. Karazin Kharkiv National University Radiophysical Observatory were employed. The data obtained at the “Lviv” Magnetic Observatory were used for making intercomparison. Findings: The radiophysical observations have been made of the dynamic processes acting in the ionosphere during the solar eclipse of 10 June 2021 and on the reference days. The temporal variations in the Doppler frequency shift observed at vertical and oblique radio paths have been found to be, as a whole, similar. Generally speaking, the Doppler spectra over these radio propagation paths were different. Over the oblique radio paths, the number of rays was greater. The solar eclipse was accompanied by wave activity enhancement in the atmosphere and ionosphere. At least three wave trains were observed. The values of the periods (about 5–12 min) and the relative amplitudes of perturbations in the electron density (δN≈0.3–0.6 %) give evidence that the wave disturbances were caused by atmospheric gravity waves. The amplitude of the 6–8-min period geomagnetic variations has been estimated to be 0.5–1 nT. Approximately the same value has been recorded in the X component of the geomagnetic field at the nearest Magnetic Observatory. The aperiodic effect of the solar eclipse has appeared to be too small (less than 0.01 Hz) to be observed confidently. The smallness of the effect was predetermined by an insignificant magnitude of the partial eclipse over the City of Kharkiv (no more than 0.11). Conclusions: The features of the solar eclipse of 10 June 2021 include an insignificant magnitude of the aperiodic effect and an enhancement in wave activity in the atmosphere and ionosphere. Key words: solar eclipse; ionosphere; Doppler spectrum; Doppler frequency shift; electron density; geomagnetic field; atmospheric gravity wave

Declination magnetic charts for Mexico since 1907.0 to 2010.0

2021 ◽  
Author(s):  
Alejandro Paredes-Arriaga ◽  
Ana Caccavari-Garza ◽  
Esteban Hernández-Quintero ◽  
Gerardo Cifuentes-Nava
Keyword(s):  
Statistical Analysis ◽  
Numerical Method ◽  
Geomagnetic Field ◽  
Magnetic Measurements ◽  
Temporal Variations ◽  
Magnetic Data ◽  
Magnetic Observatory ◽  
Average Data ◽  
Spatial Estimation ◽  
Made In

&lt;p&gt;We present the construction of magnetic declination charts corresponding to five epochs for last one hundred years; this was result of recovery and statistical analysis of historical magnetic data. The charts were made with the records of magnetic repeat stations reoccupation, distributed throughout the country, the goal was to observe and study the geomagnetic field morphology and their space-temporal variations in Mexico. We aimed to systematize an optimal numerical method for the spatial estimation to minimize the error given the average data for any Mexican magnetic chart: forty magnetic repeat stations and only one magnetic observatory. Also, the charts were compared with the original charts made in its corresponding epoch. The charts quality was improved and the historic geomagnetic information preserved, considering the invaluable record of historical magnetic measurements that exist in Mexico.&lt;/p&gt;

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