scholarly journals ANALYSIS OF THE DAILY HOURLY DEPARTURES OF THE GEOMAGNETIC H FIELD OVER LOW-LATITUDE STATIONS

2020 ◽  
Vol 3 (1) ◽  
pp. 1-14
Author(s):  
I.A Adimula ◽  
G.I. Ojerheghan
Keyword(s):  
Correlation Coefficients ◽  
Communication Technologies ◽  
Geomagnetic Disturbances ◽  
Low Latitude ◽  
The Earth ◽  
Telecommunication Companies ◽  
Baseline Values ◽  
Rotation Of The Earth ◽  
The 19Th Century

The telecommunication technologies deployed in the last decades have shown that there are better days ahead. From electric telegraphs systems in the 19th century to today’s wireless communication using satellites and land links (Lanzerotti, 2001). The horizontal component (H-field) of the geomagnetic field has great impacts in the present-day communication technologies. The aim of this paper was to analyse the daily hourly departures of geomagnetic H-field along the low-latitude stations on the equatorial chain in relation to their correlation coefficients with their longitudes. The magnitude of H-component is a very significant factor in the determination of the total magnetic field of any location on the earth. The baseline values (H0) which is the average of H components at 23LT, 24LT, 1LT and 2LT were subtracted from the hourly values of H (Ht) to obtain the hourly departures of H (dH). The hourly departures of H (dH) from the baseline is non-cyclic since H1 ≠ H24 as observed over the three MAGDAS stations in Nigeria. The correlation coefficients between dHs of Lagos/Ilorin, Ilorin/Abuja and Abuja/Ilorin are 0.97, 0.75 and 0.66 respectively. This suggests that substorms are deflected eastwards along different longitudes due to the rotation of the earth such that locations in the same longitudes have the same hourly departures. There is no solar radiation during the nighttime, thus dH should be zero but for the energy stored in the magnetotail, the reduction of hourly departures towards nighttime in Nigeria is evident. This is further revealed as the midnight dH amplitudes decrease regularly. The eastward motion of the electrons during substorms was suggested to be responsible for the reduction of the H-field at the nightside magnetotail region for all the stations. These findings will assist the telecommunication companies to know which location is best for their transmitters to be sited in order to reduce loss of signals along the optical cables to the receivers. Furthermore, global telecomms companies should have business continuity plan which should include risk assessment and prompt response to geomagnetic disturbances being one of the causes for telecommunication outages.

Addendum 2020 to ‘Measurement of the Earth’s rotation: 720 BC to AD 2015’

2021 ◽  
Vol 477 (2246) ◽  
pp. 20200776
Author(s):  
L. V. Morrison ◽  
F. R. Stephenson ◽  
C. Y. Hohenkerk ◽  
M. Zawilski
Keyword(s):  
Angular Momentum ◽  
Earth’S Rotation ◽  
The Sun ◽  
Earth's Rotation ◽  
Moon System ◽  
Link Type ◽  
The Earth ◽  
Solar Eclipses ◽  
Rotation Of The Earth

Historical reports of solar eclipses are added to our previous dataset (Stephenson et al. 2016 Proc. R. Soc. A 472 , 20160404 ( doi:10.1098/rspa.2016.0404 )) in order to refine our determination of centennial and longer-term changes since 720 BC in the rate of rotation of the Earth. The revised observed deceleration is −4.59 ± 0.08 × 10 −22  rad s −2 . By comparison the predicted tidal deceleration based on the conservation of angular momentum in the Sun–Earth–Moon system is −6.39 ± 0.03 × 10 −22  rad s −2 . These signify a mean accelerative component of +1.8 ± 0.1 × 10 −22  rad s −2 . There is also evidence of an oscillatory variation in the rate with a period of about 14 centuries.

scholarly journals Commission 19: Rotation of the Earth

1985 ◽  
Vol 19 (1) ◽  
pp. 193-205 ◽  
Author(s):  
Ya. S. Yatskiv ◽  
W. J. Klepczynski ◽  
F. Barlier ◽  
H. Enslin ◽  
C. Kakuta ◽  
...  
Keyword(s):  
Time Frame ◽  
Laser Ranging ◽  
Earth’S Rotation ◽  
The Moon ◽  
Earth's Rotation ◽  
The Earth ◽  
Long Time ◽  
Terrestrial Reference System ◽  
Rotation Of The Earth

During the period, work on the problem of the Earth’s rotation has continued to expand and increase its scope. The total number of institutions engaged in the determination of the Earth’s rotation parameters (ERP) by different techniques has been increased significantly. The rotation of the Earth is currently measured by classical astrometry, Doppler and laser satellite tracking, laser ranging of the Moon, and radio interferometry. Several long time series of the ERP are available from most of these techniques, in particular, those made during the Main Campaign of the MERIT project. The various series have been intercompared and their stability, in the time frame of years to days, has been estimated for the purposes of establishing a new conventional terrestrial reference system (COTES). On the other hand, the difficulties of maintaining a regular operation for laser ranging to the Moon (LLR) have been recognized. It resulted in the proposal to organize an one-month campaign of observations in 1985 in order to complement the COTES collocation program and to allow additional intercomparisons with other techniques.

scholarly journals New Determination of the “Decade” Fluctuations in the Rotation of the Earth 1860–1978

1979 ◽  
Vol 82 ◽  
pp. 55-57
Author(s):  
L. V. Morrison
Keyword(s):  
Angular Momentum ◽  
Electromagnetic Coupling ◽  
Viscous Stress ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
Topographic Features ◽  
The Core ◽  
The Earth ◽  
Rotation Of The Earth

Observations of the Earth's rotation have shown irregular variations of rate which have characteristic times of decades. These have been attributed to transfer of angular momentum between core and mantle by some mechanism such as inertial coupling, viscous stress, electromagnetic coupling or stresses produced by topographic features on the core mantle boundary.

Polar motion and earth tides from laser tracking

1977 ◽  
Vol 284 (1326) ◽  
pp. 485-494 ◽  
Keyword(s):  
Earth Tides ◽  
Length Of Day ◽  
Laser Tracking ◽  
The Earth ◽  
New Information ◽  
Single Station ◽  
Laser Systems ◽  
Rotation Of The Earth ◽  
Better Than

The tracking of near-Earth satellites with laser systems permits the determination of the variation of latitude of the tracking station and the variation in the rotation of the Earth. The present-day capability of a single station is approximately 75 cm in latitude averaged over 6h and 0.8 ms in the length of day. When the Laser Geodynamics Satellite (Lageos) is launched, a network of laser stations is projected to be able to achieve better than 10 cm in each coordinate from less than one day of tracking. The perturba­tions of near-Earth satellites by solid Earth and ocean tides are now measurable and can provide new information about the Earth and oceans. The orbit perturbations have long periods (days, months) and the analysis of orbital changes are providing estimates of the amplitudes and phases of the major tidal components.

Geodetic foundations of cartography in Europe in 19th century

2021 ◽  
Vol 977 (11) ◽  
pp. 51-64
Author(s):  
М. Lapaine
Keyword(s):  
19Th Century ◽  
Southeastern Europe ◽  
Coordinate Systems ◽  
Astronomical Observations ◽  
The Earth ◽  
Introductory Part ◽  
History Of ◽  
The 19Th Century ◽  
Geodetic Surveying

Geodetic surveying comprises the determination of locations on and the dimensions of the earth’s surface at a various scales. In the 19th century, its technologies are those of direct measurement of the earth’s surface combined with astronomical observations. Its social context encompasses all those individuals and institutions involved in the creation, preservation, use, and arrangement of knowledge of the earth. In the introductory part of the paper the author mentions several important events in the history of the 19th century geodesy. Geodetic work on determining the size of the Earth by measuring the lengths of the meridian arcs continues in this century. An international surveying organization was established and the international meter convention adopted. Basing on a detailed research of geodetic surveying in Central, Eastern and Southeastern Europe in the 19th century, a part of these surveys is presented that relates to Switzerland, Austro-Hungarian Monarchy, Austria, Hungary, Slovenia and Croatia. Common to all these geodetic surveys is that they were necessary for the development of cartography and were carried out by military institutions. The developed geodetic networks are characterized by the use of different ellipsoids, different prime meridians, different coordinate systems and their origin. In the area under consideration in the 19th century, there were five different ellipsoids in use suggested by Bessel, Bonenberger, Schmidt, Valbeck and Zach. Prime meridians were

scholarly journals Rotation of the Solar System Bodies

1992 ◽  
Vol 9 ◽  
pp. 508-536
Author(s):  
B. Kolaczek
Keyword(s):  
Solar System ◽  
Solid Body ◽  
Artificial Satellites ◽  
The Moon ◽  
The Earth ◽  
Photometric Observations ◽  
Solar System Bodies ◽  
Rotation Of The Earth ◽  
Better Than

Solar System bodies are different. They have different sizes, from large planets to small asteroids, and shapes. They have different structure, from solid body to solid body with fluid atmosphere or core, to gaseous bodies, but all of them rotate. The Solar System is a big laboratory for studying rotation of solid and fluid bodies.Different observational methods are applied to determine the rotation of the Solar system bodies. They depend on the position of the observer and on the structure of the bodies. The most accurate methods, laser ranging to the Moon and artificial satellites and Very Long Base radio Interferometry have been applied to the determination of the rotation of the Earth and the Moon. Their accuracy is better than 0.001”, which on the surface of the Earth corresponds to about 3 cm. Radiotracking of artifical satellites have been used for Earth, Moon, Venus, Mars. In the case of Jupiter, Saturn, Uranus, Neptune and Pluto-Charon magnetic and photometric observations have been used respectively. Their accuracy is of the order of one tenth of a degree.

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