scholarly journals Moving daily average of the hourly magnetic field values - the example of usage at Novosibirsk Observatory during 2011 (results and prospects)

2020 ◽  
Vol 196 ◽  
pp. 02020
Author(s):  
Nikolay Semakov ◽  
Aleksandr Kovalev ◽  
Anatoliy Pavlov ◽  
Olga Fedotova
Keyword(s):  
Magnetic Field ◽  
Digital Data ◽  
Magnetic Pole ◽  
Mean Values ◽  
The North ◽  
Central Dipole ◽  
Regional Features ◽  
North Magnetic Pole ◽  
Magnetic Constant ◽  
The Magnetic Field

The parameters of the equivalent central dipole calculated using hourly values of the magnetic field elements during 2011: the angular elements transformed to the hourly values of the geographic coordinates of the North magnetic pole and the intensity values transformed to local magnetic constant. Next step is the calculation of the daily mean values at every hour. This method applied to both current digital data and historical data presented as monthly tables of hourly values. The advantage of method is its ability to show the changes of the magnetic field independently from daily variation. Using of the “integrate” parameters (the magnetic pole coordinates and local magneto constant) allows detect the regional features of its variations. The features in the daily values compared with anomalous geological and geophysical events observed in the past and predicted in the near future.

An analytical representation of the geomagnetic field in Canada for 1975. Part II: The secular change

1978 ◽  
Vol 15 (2) ◽  
pp. 237-244 ◽  
Author(s):  
E. Dawson ◽  
L. R. Newitt
Keyword(s):  
Magnetic Field ◽  
Secular Change ◽  
Main Magnetic Field ◽  
Annual Change ◽  
Mean Values ◽  
The North ◽  
Magnetic Inclination ◽  
Polynomial Extrapolation ◽  
Annual Means ◽  
The Magnetic Field

Annual mean values of the north (X), east (Y) and vertical (Z) components of the magnetic field from 20 observatories in Canada and adjacent countries for the period 1955–1976 are used to test secular change derived from cubic time terms in a polynomial model. This model was used to derive the main magnetic field charts of Canada for 1975. The rms deviation in the secular change for 1975 (annual change) is a disappointing 16 nT. Graphs of observed and computed annual means show that this fit will worsen with time, especially in Y and Z. For these reasons the annual change contours on the above-mentioned charts were derived by conventional graphical methods. Graphs of the magnetic declination (D), the horizontal intensity (H) and Z were drawn for 20 observatories and 157 Canadian and American repeat stations. Values were extrapolated to 1975 and contoured. A comparison of graphical and polynomial methods show that this simple graphical extrapolation is more sensitive to small significant secular changes than a polynomial extrapolation. We show annual change charts in X, Y and Z constructed by this method.The movement of centres of intense secular change, called isoporic foci, in X, Y and Z, are examined to determine their influence on the secular change pattern in Canada. These indicate that Y and D will continue to decrease, while X and H will continue to increase over most of the country. The total intensity (F), the magnetic inclination (I), and Z will all decrease rapidly in southern Canada.

scholarly journals Geomagnetic-Heliomagnetic Modulation of Atmospheric Radiocarbon Production

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 266-278 ◽  
Author(s):  
Paul E Damon ◽  
Timothy W Linick
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
High Latitude ◽  
Ice Core ◽  
Cosmic Ray ◽  
Dipole Field ◽  
Phase Lag ◽  
Magnetic Pole ◽  
The North ◽  
North Magnetic Pole

New Arizona high precision Δ14C data back to 6500 BC plot close to an 11,300-yr period sinusoid extrapolated from the post 5300 BC data (offset = +32‰, half amplitude = 51‰ and phase lag = 2.29 radians). The trend curve is modulated by high latitude components of the non-dipole field with a fundamental period of 2400 yr. Based upon a model of Lund and Banerjee (1985), the non-dipole field rotates and every 1200 yr the high latitude maxima pass over the north magnetic pole and near the south magnetic pole in reversed polarity. This modulates cosmic ray production producing extended maxima ca AD 1700, 700 bc, 3100 bc, and 5500 bc. The 2400 period appears to be stationary. The magnetic field also modulates the amplitude of the solar activity induced cycles of periods 200, 80, and 11 yr as can be seen in the Zürich-Bern Camp Century ice core data as well as in the Δ14 C fluctuation data. Reinterpretation of the Camp Century 10Be data indicates that it is in agreement with magnetic field as well as solar activity modulation of terrestrial radioisotope production.

scholarly journals Circumstellar environment of 55 Cancri

2020 ◽  
Vol 633 ◽  
pp. A48 ◽  
Author(s):  
C. P. Folsom ◽  
D. Ó Fionnagáin ◽  
L. Fossati ◽  
A. A. Vidotto ◽  
C. Moutou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Stellar Wind ◽  
Large Scale ◽  
Rotation Axis ◽  
Doppler Imaging ◽  
Magnetic Pole ◽  
Average Strength ◽  
Detailed Understanding ◽  
The Magnetic Field ◽  
Circumstellar Environment

Context. 55 Cancri hosts five known exoplanets, most notably the hot super-Earth 55 Cnc e, which is one of the hottest known transiting super-Earths. Aims. Because of the short orbital separation and host star brightness, 55 Cnc e provides one of the best opportunities for studying star-planet interactions (SPIs). We aim to understand possible SPIs in this system, which requires a detailed understanding of the stellar magnetic field and wind impinging on the planet. Methods. Using spectropolarimetric observations and Zeeman Doppler Imaging, we derived a map of the large-scale stellar magnetic field. We then simulated the stellar wind starting from the magnetic field map, using a 3D magneto-hydrodynamic model. Results. The map of the large-scale stellar magnetic field we derive has an average strength of 3.4 G. The field has a mostly dipolar geometry; the dipole is tilted by 90° with respect to the rotation axis and the dipolar strength is 5.8 G at the magnetic pole. The wind simulations based on this magnetic geometry lead us to conclude that 55 Cnc e orbits inside the Alfvén surface of the stellar wind, implying that effects from the planet on the wind can propagate back to the stellar surface and result in SPI.

Detection of a change in the North-South ratio of count rates of particles of high-energy cosmic rays during a change in the polarity of the magnetic field of the Sun

JETP Letters ◽  
2015 ◽  
Vol 101 (4) ◽  
pp. 228-231
Author(s):  
A. V. Karelin ◽  
O. Adriani ◽  
G. C. Barbarino ◽  
G. A. Bazilevskaya ◽  
R. Bellotti ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
High Energy ◽  
The Sun ◽  
High Energy Cosmic Rays ◽  
The North ◽  
The Magnetic Field

scholarly journals Expedition to the North Magnetic Pole

1902 ◽  
Vol 20 (6) ◽  
pp. 627
Author(s):  
Roald Amundsen
Keyword(s):  
Magnetic Pole ◽  
The North ◽  
North Magnetic Pole

A two-dimensional analysis of the compressible flow near a reconnection site at the dayside magnetopause

2007 ◽  
Vol 73 (1) ◽  
pp. 89-115 ◽  
Author(s):  
LARS G. WESTERBERG ◽  
HANS O. ÅKERSTEDT
Keyword(s):  
Magnetic Field ◽  
Transition Layer ◽  
Alfven Wave ◽  
The North ◽  
Dayside Magnetopause ◽  
Reconnection Site ◽  
Ideal Magnetohydrodynamic ◽  
North And South ◽  
Magnetic Field Variations ◽  
The Magnetic Field

Abstract.A compressible model of the magnetosheath plasma flow is considered. Magnetic reconnection is assumed to occur in a region stretching from the sub-Solar point to the north. Two locations of the reconnection site are treated: two and four Earth radii from the sub-Solar point, respectively. By treating the transition layer as very thin, we solve the governing equations approximately using the method of matched asymptotic expansions. The behavior of the magnetic field and the plasma velocity close to a reconnection site during the transition from the magnetosheath to the magnetosphere is investigated. We also obtain the development of the transition layer thickness north and south of the reconnection point. The magnetopause transition layer is represented by a large-amplitude Alfvén wave implying that the density is approximately the same across the magnetopause boundary. In order to match the solutions we consider a compressible ideal magnetohydrodynamic model describing density, velocity and magnetic field variations along the outer magnetopause boundary. We also compare the analytical results with solutions from a numerical simulation. The compressible effects on the structure of the magnetic field and the total velocity evolution are visible but not dramatic. It is shown that the transition layer north of the reconnection point is thinner than to the south. The effect is stronger for reconnection at higher latitudes.

Investigation on the Improvement of Surface Quality by the Magnetic Plate-Assisted Magnetic Abrasive Finishing Process

2021 ◽  
Vol 1018 ◽  
pp. 111-116
Author(s):  
Yan Hua Zou ◽  
Hui Jun Xie
Keyword(s):  
Magnetic Field ◽  
Surface Quality ◽  
Field Distribution ◽  
Magnetic Field Distribution ◽  
Magnetic Flux Density ◽  
Magnetic Pole ◽  
Magnetic Abrasive Finishing ◽  
Abrasive Finishing ◽  
Glass Lens ◽  
The Magnetic Field

The traditional magnetic abrasive finishing (MAF) process, the magnetic flux density at the bottom of the magnetic pole is unevenly distributed, resulting in poor uniformity of the finished surface. Therefore, it is proposed to improve the surface quality by attaching a magnetic plate at the bottom of the workpiece to improve the magnetic field distribution. It is confirmed by simulation that the magnetic field distribution at the bottom of the magnetic pole is effectively improved after the magnetic plate is attached. It is proved through experiments that the magnetic plate-assisted MAF process can obtain a smoother surface. The experimental results show that the surface roughness of the glass lens improves from 246 nm Ra to 3 nm Ra through the magnetic plate-assisted MAF process within 45min.

SOME RESULTS OF AEROMAGNETIC SURVEYING WITH A DIGITAL CESIUM‐VAPOR MAGNETOMETER

Geophysics ◽  
1965 ◽  
Vol 30 (5) ◽  
pp. 883-890 ◽  
Author(s):  
Raoul I. Giret
Keyword(s):  
Magnetic Field ◽  
Optical Pumping ◽  
Digital Data ◽  
Cesium Vapor ◽  
Ground Station ◽  
Digital Frequency ◽  
Record Data ◽  
Frequency Meter ◽  
Magnetic Record ◽  
The Magnetic Field

This magnetometer has been developed by C.S.F. (Compagnie Générale de Télégraphie Sans Fil) and C.G.G. (Compagnie Générale de Géophysique). The magnetic field is measured by an optical pumping sensor giving a frequency proportional to the field. A digital frequency‐meter delivers a reading each second with a sensitivity of ± one period (31.5 periods for one gamma). These readings are recorded on a magnetic tape recorder and on an analog TEXAS recorder. The digital data are processed on a 1620 IBM. During the flight a second magnetometer records the variation of the earth’s field in a ground station located in the center of the area surveyed. The ground record data are subtracted from the airborne data. The following data obtained with this equipment are presented: Analog record with a sensitivity of one gamma for two mm. Restitution with 1620 IBM and CALCOMP of the magnetic record to an analog record with a sensitivity of one gamma for one cm. Isogam maps with a contour interval of one gamma and some intermediate contours at 0.5 gamma.

scholarly journals Some Properties of Magnetic Variables

1971 ◽  
Vol 15 ◽  
pp. 59-62 ◽  
Author(s):  
Karl D. Rakoš
Keyword(s):  
Magnetic Field ◽  
Light Curve ◽  
Spectral Lines ◽  
Light Curves ◽  
Magnetic Pole ◽  
Yellow Light ◽  
The Past ◽  
Oblique Rotator ◽  
Ap Stars ◽  
The Magnetic Field

It is certain, that the mechanism causing variations of the magnetic field and spectral lines in Ap stars must also cause variations in their luminosities. The light curves are synchronous with the magnetic variations and usually the maximum of the positive magnetic field strength coincides with the minimum of the light curve. In the past the oblique rotator theory was not able to explain easily such brightness change. There is no simple reason to suppose, that the brightness of the surface of a star would increase or decrease at one magnetic pole only. Since that time a few stars were found with some indications for secondary minima and maxima in the light curves, but the first established double wave in a light curve was recently found by H. M. MAITZEN and K. D. RAKOš in HD 125 248 (1970), see Figure 1. It is a very exciting result, only the light curve in yellow light shows two maxima and two minima. The light curves in blue and ultraviolet are very smooth and show no evidence for secondary waves.

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