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

2021 ◽  
Vol 13 (2) ◽  
pp. 809-825
Author(s):  
Anna L. Morozova ◽  
Paulo Ribeiro ◽  
M. Alexandra Pais
Keyword(s):  
20Th Century ◽  
Geomagnetic Field ◽  
Magnetic Observatory ◽  
Time Interval ◽  
Historical Series ◽  
Long Lifetime ◽  
The Absolute ◽  
Nearly Continuous ◽  
Continue Work ◽  
Artificial Changes

Abstract. The Coimbra Magnetic Observatory (COI), Portugal, established in 1866, has provided nearly continuous records of the geomagnetic field elements for more than 150 years. However, during its long lifetime inevitable changes to the instruments and measurement procedures and even the relocation of the observatory have taken 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 on 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 the 2015 epoch. Since all series except D have a gap of about 10 years 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 the D series homogenized for the whole time interval of 1866–2015). The COI geomagnetic field elements are available via the following addresses: https://doi.org/10.5281/zenodo.4308022 (Ribeiro et al., 2020) for the original COI data (ASCII and XLSX formats) and https://doi.org/10.5281/zenodo.4308036 (Morozova et al., 2020) for the homogenized COI data (ASCII and XLSX formats).

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 Contribution to solving the orientation problem for an automatic magnetic observatory

2013 ◽  
Vol 2 (1) ◽  
pp. 1-9 ◽  
Author(s):  
A. Khokhlov ◽  
J. L. Le Mouël ◽  
M. Mandea
Keyword(s):  
Vertical Component ◽  
Calibration Procedure ◽  
High Accuracy ◽  
Absolute Calibration ◽  
Magnetic Observatory ◽  
Time Interval ◽  
Internal Calibration ◽  
Scale Factors ◽  
The Absolute ◽  
Absolute Measurements

Abstract. The problem of the absolute calibration of a vectorial (tri-axial) magnetometer is addressed with the objective that the apparatus, once calibrated, gives afterwards, for a few years, the absolute values of the three components of the geomagnetic field (say the Northern geographical component, Eastern component and vertical component) with an accuracy on the order of 1 nT. The calibration procedure comes down to measure the orientation in space of the three physical axes of the sensor or, in other words, the entries of the transfer matrix from the local geographical axes to these physical axes. Absolute calibration follows indeed an internal calibration which provides accurate values of the three scale factors corresponding to the three axes – and in addition their relative angles. The absolute calibration can be achieved through classical absolute measurements made with an independent equipment. It is shown – after an error analysis which is not trivial – that, while it is not possible to get the axes absolute orientations with a high accuracy, the assigned objective (absolute values of the Northern geographical component, Eastern component and vertical component, with an accuracy of the order of 1 nT) is nevertheless reachable; this is because in the time interval of interest the field to measure is not far from the field prevailing during the calibration process.

scholarly journals Solving the orientation problem for an automatic magnetic observatory

2012 ◽  
Vol 2 (1) ◽  
pp. 337-363
Author(s):  
A. Khokhlov ◽  
J. L. Le Mouël ◽  
M. Mandea
Keyword(s):  
Vertical Component ◽  
Calibration Procedure ◽  
High Accuracy ◽  
Absolute Calibration ◽  
Magnetic Observatory ◽  
Time Interval ◽  
Internal Calibration ◽  
Scale Factors ◽  
The Absolute ◽  
Absolute Measurements

Abstract. The problem of the absolute calibration of a vectorial (tri-axial) magnetometer is addressed with the objective that the apparatus, once calibrated, gives afterwards, for a few years, the absolute values of the three components of the geomagnetic field (say the Northern geographical component, Eastern component and vertical component) with an accuracy of the order of 1 nT. The calibration procedure comes down to measure the orientation in space of the three physical axes of the sensor or, in other words, the entries of the transfer matrix from the local geographical axes to these physical axes. Absolute calibration follows indeed an internal calibration which provides accurate values of the three scale factors corresponding to the three axes – and in addition their relative angles. The absolute calibration can be achieved through classical absolute measurements made with an independent equipment. It is shown – after an error analysis which is not trivial – that, while it is not possible to get the axes absolute orientations with a high accuracy, the assigned objective (absolute values of the Northern geographical component, Eastern component and vertical component, with an accuracy of the order of 1 nT) is nevertheless reachable; this is because in the time interval of interest the field to measure are not far from the field prevailing during the calibration process.

The connection between the «color revolutions» and the strategic doctrines of the United States (late 20th century — 2014)

2021 ◽  
Author(s):  
Anna Igorevna Filimonova
Keyword(s):  
United States ◽  
20Th Century ◽  
American Foreign Policy ◽  
Use Of Force ◽  
The United States ◽  
Time Interval ◽  
Late 20Th Century ◽  
The Us ◽  
Color Revolutions ◽  
The Right

After the collapse of the USSR, fundamentally new phenomena appeared on the world arena, which became a watershed separating the bipolar order from the monopolar order associated with the establishment of the US global hegemony. Such phenomena were the events that are most often called «revolutions» in connection with the scale of the changes being made — «velvet revolutions» in the former Eastern Bloc, as well as revolutions of a different type, which ended in a change in the current regimes with such serious consequences that we are also talking about revolutionary transformations. These are technologies of «color revolutions» that allow organizing artificial and seemingly spontaneous mass protests leading to the removal of the legitimate government operating in the country and, in fact, to the seizure of power by a pro-American forces that ensure the Westernization of the country and the implementation of "neoliberal modernization", which essentially means the opening of national markets and the provision of natural resources for the undivided use of the Western factor (TNC and TNB). «Color revolutions» are inseparable from the strategic documents of the United States, in which, from the end of the 20th century, even before the collapse of the USSR, two main tendencies were clearly traced: the expansion of the right to unilateral use of force up to a preemptive strike, which is inextricably linked with the ideological justification of «missionary» American foreign policy, and the right to «assess» the internal state of affairs in countries and change it to a «democratic format», that is, «democratization». «Color revolutions», although they are not directly mentioned in strategic documents, but, being a «technical package of actions», straightforwardly follow from the right, assigned to itself by Washington, to unilateral use of force, which is gradually expanding from exclusively military actions to a comprehensive impact on an opponent country, i.e. essentially a hybrid war. Thus, the «color revolutions» clearly fit into the strategic concept of Washington on the use of force across the entire spectrum (conventional and unconventional war) under the pretext of «democratization». The article examines the period of registration and expansion of the US right to use force (which, according to the current international law, is a crime without a statute of limitations) in the time interval from the end of the twentieth century until 2014, filling semantic content about the need for «democratic transformations» of other states, with which the United States approached the key point of the events of the «Arab spring» and «color revolutions» in the post-Soviet space, the last and most ambitious of which was the «Euromaidan» in Ukraine in 2014. The article presents the material for the preparation of lectures and seminars in the framework of the training fields «International Relations» and «Political Science».

scholarly journals Paleoenvironmental and paleobiological origins of coccolithophorid genusWatznaueriaemergence during the late Aalenian–early Bajocian

Paleobiology ◽  
2015 ◽  
Vol 41 (3) ◽  
pp. 415-435 ◽  
Author(s):  
Baptiste Suchéras-Marx ◽  
Emanuela Mattioli ◽  
Fabienne Giraud ◽  
Gilles Escarguel
Keyword(s):  
Marine Invertebrate ◽  
Time Interval ◽  
Calcareous Nannofossils ◽  
Calcareous Nannoplankton ◽  
Absolute Abundance ◽  
The Pacific ◽  
Relative Abundances ◽  
The Absolute ◽  
Oceanic Plates ◽  
Central Atlantic

AbstractThe latest Aalenian–early Bajocian time interval (ca. 171-169 Ma) is marked by a global reorganization of oceanic plates with the Central Atlantic opening and the formation of the Pacific plate. This time interval is also marked by a global geochemical perturbation of δ13C with a negative excursion at the Aalenian/Bajocian boundary and a positive excursion during the early Bajocian. Evolutionary diversifications of marine invertebrate taxa, namely ammonites, radiolarians, and coccolithophorids, are recorded at that time. Concerning coccolithophorids, this interval witnesses the diversification and expansion of the most successful Mesozoic genus:Watznaueria. In this study, we explore the potential environmental, ecological, and biological forcing at the origin ofWatznaueriadiversification and its effect on the coccolith assemblages through quantification of the absolute and relative abundances of calcareous nannofossils in two Middle Jurassic key sections: Cabo Mondego (Portugal) and Chaudon-Norante (France). In both sections, we find an increase in nannofossil absolute abundance and flux at the beginning of the lower Bajocian, coeval with an increase in absolute and relative abundances ofWatznaueriaspp., followed by a plateau in the middle and upper part of the lower Bajocian. The increase ofWatznaueriaspp. is synchronous with a decrease in relative abundance of other major coccolith taxa, whereas the absolute abundance of these species did not decrease. During the climatically driven early Bajocian eutrophication event,Watznaueriaspp. integrated into the calcareous nannoplankton community in two successive evolutionary steps involving firstW. contractaandW. colaccicchii, and secondW. britannicaandW.aff.manivitiae. Step 1 was driven by an increase in niche carrying capacities linked to the early Bajocian eutrophication. Step 2 was driven by specific adaptation of the newly evolvedWatznaueriaspecies to bloom in nutrient-rich environments not exploited before. These evolutionary events have initiated the 100-Myr reign ofWatznaueriaover the calcareous nannoplankton community.

scholarly journals A tectonomagnetic effect detected in Central Italy

1994 ◽  
Vol 37 (1) ◽  
Author(s):  
G. Mele ◽  
A. Meloni ◽  
P. Palangio
Keyword(s):  
Field Intensity ◽  
Geomagnetic Field ◽  
Central Italy ◽  
Volcanic Eruptions ◽  
Intensity Data ◽  
Absolute Level ◽  
Tectonic Events ◽  
Railway System ◽  
The Absolute ◽  
Geomagnetic Intensity

Significant variations in the absolute value of the geomagnetic field intensity related to tectonic events, as earthquakes and volcanic eruptions, have been observed in several cases. To detect such a tectonomagnetic effect related to seismic activity, a seismomagnetic network was installed by the Istituto Nazionale di Geofisica (ING) in the Abruzzi region (CentraI Italy), in July 1989. This area is being uplifting since the Pliocene. A logistic compromise between geophysical requirements and the electrified railway system tracks distribution led to the installation of five total magnetic field intensity data acquisition sites. From July 1989 to September 1992 geomagnetic intensity data were simultaneously recorded at all stations and compared to that recorded at the L'Aquila Observatory, located in the same area. A variation of about 10 nT in the absolute level of the geomagnetic field was measured at two stations located on the eastern side of the network. We suggest that the detected magnetic anomaly could resuIt from aseismic-changes in crustal stress during this time.

scholarly journals Few years' experience with Automatic DIFlux systems: theory, validation and results

2017 ◽  
Author(s):  
Antoine Poncelet ◽  
Alexandre Gonsette ◽  
Jean Rasson
Keyword(s):  
Systems Theory ◽  
Magnetic Observatory ◽  
Proof Of Concept ◽  
The Absolute

Abstract. The previous release of our Automatic DIFlux, called AutoDIF mk2.2, is now running continuously since June 2012 in the absolute house of Dourbes magnetic observatory performing measurement every 30 minutes. A second one is working in the tunnel of Conrad observatory (Austria) since December 2013. After this proof of concept, we improved the AutoDIF to the version mk2.3 which was presented in 16th IAGA workshop in Hyderabad. Today, we have successfully deployed 6 AutoDIFs in various environments: 2 in Dourbes (DOU), 1 in Manhay (MAB), 1 in Conrad (CON), 1 in Deajeon (Korea) and 1 is used for tests. This one was installed for 10 month in Chambon-la-Foret (CLF) and since 2016 in Kakioka (KAK). In this paper, we will compare the automatic measurements with the human-made, and discuss the advantages/disadvantages of automatic measurements

scholarly journals Multidecadally resolved polarity oscillations during a geomagnetic excursion

2018 ◽  
Vol 115 (36) ◽  
pp. 8913-8918 ◽  
Author(s):  
Yu-Min Chou ◽  
Xiuyang Jiang ◽  
Qingsong Liu ◽  
Hsun-Ming Hu ◽  
Chung-Che Wu ◽  
...  
Keyword(s):  
20Th Century ◽  
Geomagnetic Field ◽  
Early 20Th Century ◽  
Human Society ◽  
Before Present ◽  
Earth History ◽  
Geomagnetic Excursion ◽  
Deep Interior ◽  
Polarity Reversals ◽  
Chinese Stalagmite

Polarity reversals of the geomagnetic field have occurred through billions of years of Earth history and were first revealed in the early 20th century. Almost a century later, details of transitional field behavior during geomagnetic reversals and excursions remain poorly known. Here, we present a multidecadally resolved geomagnetic excursion record from a radioisotopically dated Chinese stalagmite at 107–91 thousand years before present with age precision of several decades. The duration of geomagnetic directional oscillations ranged from several centuries at 106–103 thousand years before present to millennia at 98–92 thousand years before present, with one abrupt reversal transition occurring in one to two centuries when the field was weakest. These features indicate prolonged geodynamo instability. Repeated asymmetrical interhemispheric polarity drifts associated with weak dipole fields likely originated in Earth’s deep interior. If such rapid polarity changes occurred in future, they could severely affect satellites and human society.

scholarly journals Results of the Helsinki magnetic observatory 1844-1912

2004 ◽  
Vol 22 (5) ◽  
pp. 1691-1704 ◽  
Author(s):  
H. Nevanlinna
Keyword(s):  
Secular Variation ◽  
Solar Rotation ◽  
Sudden Change ◽  
Magnetic Activity ◽  
Spectral Lines ◽  
Field Analysis ◽  
Occurrence Rate ◽  
Magnetic Observatory ◽  
Time Interval ◽  
Variation Rate

Abstract. The geomagnetic field declination (D) and horizontal component (H) were observed visually at the Helsinki magnetic observatory between 1844–1912. About 2.0 million single observations of the magnetic components are available. The observing equipment and observation methods were the same for almost 70 years. The Helsinki data series is thus rather homogeneous and suitable for magnetic field analysis of both internal and external origin for about five sunspot cycles (sunspot cycles 9–13). Due to disturbances from nearby electric tramway traffic, most of the observations after 1897 are very noisy and unreliable for magnetic activity studies. Observations of D (1844–1897) have been converted into an absolute scale but H refers to variation values only. Observations of D have been previously analyzed and published for the time interval 1844–1880. In this paper we present new results of D for 1881–1897 and H for 1844–1897. The annual rate of the secular variation of D has been rather stable between 1844–1909, showing a mean eastward increase of +0.11°/year, which is about twice as large as the mean secular variation rate for the past 50 years at the same latitude in Finland. Around 1875 there was a sudden change in the secular variation rate resembling the famous jerk of 1970. Magnetic activity indices (K, Ak) for 1844–1897 were calculated from hourly values of D- and D-series separately using the IAGA K-index algorithm (the FMI-method). Comparisons with other relevant activity series from other sources (aa, u, RI, C9, auroral occurrence rate) show that the Helsinki index series gives an important contribution to the index family. By extending the Mayaud's aa-index series with Helsinki Ak-values (1844–1868), it is possible to reconstruct a (pseudo) aa-series that covers almost 160 years. Magnetic activity (space weather) was appreciably greater during the first three cycles (9–11) than during the two last ones (12–13). The largest magnetic storm occurred in September 1859. Other stormy periods were in 1847, 1852, and 1870–1872. Mean magnetic activity remained exceptionally low in years 1875–1881 and 1887–1891. In an FFT-analysis of the activity index series, the solar cycle, annual, semiannual, solar rotation and half solar rotation spectral lines are well established.Key words. Geomagnetism and paleomagnetism (time variations, diurnal to secular) – History of geophysics (planetology) – Magnetospheric physics (solar wind-magnetosphere interactions)7

scholarly journals MODEL EMPIRIS HARI TENANG VARIASI MEDAN GEOMAGNET DI STASIUN GEOMAGNET TONDANO MANADO

2016 ◽  
Vol 12 (2) ◽  
pp. 115
Author(s):  
Lukman Arifin ◽  
John Maspupu
Keyword(s):  
Solar Activity ◽  
Local Time ◽  
Empirical Model ◽  
Geomagnetic Field ◽  
Daily Variation ◽  
Geomagnetic Disturbance ◽  
Time Interval ◽  
Field Variation ◽  
Geomagnetic Field Variation ◽  
Expression Form

Penentuan model empiris hari tenang variasi medan geomagnet dikonstruksi berdasarkan data geomagnet dari stasiun geomagnet (SG) Badan Meteorologi Klimatologi dan Geofisika (BMKG) Tondano, Manado. Hari tenang variasi medan geomagnet dinyatakan sebagai fungsi dari keempat komponen atau variabel yang mempengaruhinya yaitu: aktivitas matahari SA (solar activity), hari dalam setahun DOY (date of year), usia bulan LA (lunar age) dan waktu lokal LT (local time). Dalam bentuk matematis ditulis sebagai, EMQD ( SA, DOY, LA, LT ) = f(SA). g(DOY). h(LA). m(LT). Model empiris yang didasarkan pada fungsi kecocokan ini terdiri dari 270 bentuk ekspresi matematik. Sedangkan bentuk-bentuk ekspresi matematik ini juga mencakup proses-proses non-linier yang tak dapat diabaikan dalam model empiris hari tenang variasi medan geomagnet tersebut. Model empiris ini dapat ditiru atau dikonstruksi kembali pada suatu selang waktu yang relatif panjang (misalnya satu siklus matahari), asalkan kondisi geomagnet selalu berada dalam keadaan tenang. Kontribusi dari model empiris hari tenang ini akan memberikan informasi tentang gangguan geomagnet yang ada di stasiun geomagnet Tondano (Nilai Gangguan geomagnet = Nilai variasi medan geomagnet yang terukur – Nilai model empiris hari tenang). Dengan demikian model ini akan memberikan informasi gangguan geomagnet untuk operasi survey geomagnet disekitar stasiun geomagnet Tondano, Manado. Kata kunci : Model empiris, Hari tenang, Variasi medan geomagnet. The determination an empirical model of the quiet daily geomagnetic field variation that is constructed based on geomagnetic data from Tondano, Manado station geomagnetic This quiet daily of geomagnetic field variation was described as a function of four variables that its influence, these are solar activity (SA), day of year (DOY), lunar age (LA) and local time (LT). In the mathematically writes: EMQD ( SA, DOY, LA, LT ) = f(SA). g(DOY). h(LA). m(LT). The empirical model based on this fitting function consist of 270 coefficients which included in expression form of mathematic. While, expression form of this mathematic also comprise nonlinear processes which can not minimized in the empirical model of the quiet daily geomagnetic field variation. This empirical model can be reconstructed on the time interval that is long relative (for example one solar cycle). Provided that, under geomagnetic quiet conditions. Contribution of this empirical model of the quiet daily variation is can give information about the existence of geomagnetic disturbance at Tondano (value of geomagnetic disturbance equal value of measurable geomagnetic field variation minus value of empirical model of the quiet daily variation). Thus, information about the existence of this geomagnetic disturbance very useful for necessity geomagnetic survey at Tondano, Manado geomagnetic station. Keywords: Empirical model, the quiet daily variation, geomagnetic field variation.

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