scholarly journals Magnetic storms disrupt nocturnal migratory activity in songbirds

2019 ◽  
Vol 15 (3) ◽  
pp. 20180918 ◽  
Author(s):  
Giuseppe Bianco ◽  
Mihaela Ilieva ◽  
Susanne Åkesson
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Visual Cues ◽  
Early Morning ◽  
Temporal Variations ◽  
Migratory Restlessness ◽  
Geomagnetic Variations ◽  
Migratory Activity ◽  
Solar Storm ◽  
Solar Storms

Birds possess a magnetic sense and rely on the Earth's magnetic field for orientation during migration. However, the geomagnetic field can be altered by solar activity at relative unpredictable intervals. How birds cope with the temporal geomagnetic variations caused by solar storms during migration is still unclear. We addressed this question by reproducing the effect of a solar storm on the geomagnetic field and monitoring the activity of three songbird species during autumn migration. We found that only the European robin reduced nocturnal migratory restlessness in response to simulated solar storms. At the same time, robins increased activity during early morning. We suggest that robins reduced activity at night when the perception of magnetic information would be strongly disrupted by temporal variations of the magnetic field, to extend their migration during daytime when several visual cues become available for orientation. The other two species, chiffchaff and dunnock, showing low or no nocturnal migratory activity, did not respond to the solar storm by changing activity.

scholarly journals Where are Solar storm-induced whale strandings more likely to occur?

2020 ◽  
Vol 19 (5) ◽  
pp. 413-417
Author(s):  
Klaus Heinrich Vanselow
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Norwegian Sea ◽  
Solar Eruptions ◽  
Solar Storm ◽  
Solar Storms ◽  
Navigation Errors ◽  
The Magnetic Field

AbstractWhale strandings occur in many places worldwide and numerous possible explanations for this phenomenon have been proposed, including the effects of astronomical events such as Solar eruptions on the Earth's magnetic field. Whales use the geomagnetic field for navigation, and its distortion can therefore result in whale strandings in certain regions. However, Solar storms do not have the same impact on the geomagnetic field across the whole of the Earth's surface, and positions nearer to the equator are less exposed to this phenomenon. It is therefore plausible that Solar storms can explain whale strandings at high latitude at least, but not necessarily worldwide. This review considers strandings in relation to the geographical and geomagnetic properties of locations at higher latitudes and to changes in the magnetic field over recent centuries. It also focuses on a Solar storm in December 2015. These considerations suggest that navigation errors due to Solar storms are more likely to occur at higher latitudes, particularly in sea areas where the animals might subsequently swim into a geographic trap and become stranded. For sperm whales (Physeter macrocephalus), the southern Norwegian Sea in conjunction with the shallow North Sea represents such an area.

Local diurnal variations of the geomagnetic field during magnetically quiet conditions

2021 ◽  
Author(s):  
Veronika Haberle ◽  
Aurélie Marchaudon ◽  
Pierre-Louis Blelly ◽  
Aude Chambodut
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Diurnal Variations ◽  
Short Term ◽  
Residual Signal ◽  
Field Information ◽  
Solar Storms ◽  
The Impact ◽  
Magnetic Observatories

<p>The Earth’s magnetic field as measured from ground-based magnetometers is composed of a variety of fields generated by diverse sources, spanning a broad amplitude and frequency spectrum. Long-term variable sources induce smooth changes, whereas short-term variable sources are able to induce rapid spikes in the geomagnetic field. An important aspect of Space Weather research is to understand the contribution and impact of each of these sources. In particular, knowing the amplitude and frequency of steady-like sources, like diurnal variations, enables us to determine the impact of sudden and hazardous events such as solar storms. The basic approach to this challenge is to identify the quiet magnetic field information within the recorded time-varying signal.<br>In this work, we examine the variance of the magnetically quiet diurnal and semi-diurnal components of the geomagnetic field, as recorded by ground-based magnetic observatories of the INTERMAGNET network. These variations are extracted by applying appropriately designed digital filters on the geomagnetic field time series. The residual signal is analysed in terms of local time and seasonal variations for selected locations under quiet magnetic conditions. This approach allows us to evaluate the applicability of the introduced filtering method. The obtained results improve our understanding of the driving sources of quiet currents such as the Sq current and the variations of their distributions with respect to regular solar irradiance variations. They will also contribute to a better extraction and description of the remaining/residual signal related to solar wind stimuli (e.g. ICMEs, CIRs) causing magnetic storms.</p>

The measurement of a weak alternating magnetic field in unshielded space

Metrologiya ◽  
2021 ◽  
pp. 46-59
Author(s):  
O. L. Sokol-Kutylovskii
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Induction ◽  
Geomagnetic Field ◽  
Gradient Methods ◽  
Alternating Magnetic Field ◽  
Geomagnetic Variations ◽  
Weak Magnetic Fields ◽  
Random Character

In connection with attempts to use various types of sensors for measuring weak magnetic fields in geophysics, magnetobiology, and medicine in an unshielded space, the problem of comparing the results of these measurements arose. The issues of measuring a weak alternating magnetic field by various magnetic induction sensors in an unshielded space in the absence of obvious geomagnetic variations are considered. It is shown that the amplitude of natural geomagnetic noise in a quiet geomagnetic field in the absence of geomagnetic variations has a random character; therefore, gradient methods for measuring a weak alternating magnetic field are limited from below by the level of natural geomagnetic noise. The influence of the size of sensors of a weak alternating magnetic field on the results of measurements of broadband random geomagnetic noise is noted.

Geomagnetic variations in the British Isles and their relation to electrical currents in the ocean and shallow seas

1971 ◽  
Vol 270 (1204) ◽  
pp. 289-323 ◽  
Keyword(s):  
Geomagnetic Field ◽  
Sea Water ◽  
Vertical Component ◽  
Temporal Variations ◽  
Thin Strip ◽  
Vertical Force ◽  
British Isles ◽  
Geomagnetic Variations ◽  
The North ◽  
Shallow Seas

The analysis and interpretation of the temporal variations of the geomagnetic field observed at fortny nine stations in the British Isles are presented. The variations in the horizontal components are very similar over the whole area, while the variations of the vertical force may show large differences between stations less than 80km apart. At nearly all stations there is a correlation between the variations of the vertical component and some component of the horizontal field. For variations of period exceeding 120 min, this correlation is mainly caused by electric currents induced in the Atlantic Ocean. The results are compatible with the theoretical response derived for induction in a thin strip model of the Ocean For variations of a period less than 90 min, concentrations of current also flow in the sea water surrounding the British Isles. It is postulated that these currents too are produced by induction in the Ocean, being frequency dependent branch currents flowing from the Ocean into the shallow seas. A current concentration flowing NE-SW through southern Scotland has been delineated This current, which has frequency characteristics similar to the currents in the shallow seas, could be drive by an electric potential between the North and Irish Seas. The presence of a long narrow structure in the crust with only a small conductivity contrast would then be sufficient to channel the current and produce the observed anomaly in the geomagnetic field.

scholarly journals Satellite Shows Earth's Magnetic Field Bent During a Solar Storm

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Mark Zastrow
Keyword(s):  
Magnetic Field ◽  
Earth’S Magnetic Field ◽  
Satellite Measurements ◽  
Earth's Magnetic Field ◽  
Solar Storm ◽  
Solar Storms ◽  
Harmful Radiation

When solar storms strike, they weaken Earth's defenses against harmful radiation. New satellite measurements reveal just how much.

scholarly journals Jupiter's Auroras Recharge Between Solar Storms

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Mark Zastrow
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Solar Storm ◽  
Solar Storms ◽  
New Research

New research suggests that Jupiter's magnetic field replenishes its stock of plasma during lulls in solar activity, creating spectacular displays when a solar storm hits.

scholarly journals Singular variations in geomagnetic disturbance content at auroral latitudes

2018 ◽  
Author(s):  
Abraham Abraham ◽  
Gangadharan Renuka ◽  
Cherian Ligi ◽  
Joseph Mathew Tiju ◽  
Anie Varghese Asha ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Geomagnetic Field ◽  
Temporal Variations ◽  
Auroral Oval ◽  
Geomagnetic Disturbance ◽  
The Earth ◽  
Solar Cycle 23 ◽  
Critical Latitude

Abstract. The geomagnetic field consists of temporal variations induced primarily by the variations in the interplanetary magnetic field. This paper attempts to develop the latitude profile of fluctuations in the geomagnetic field for 34 observatories across the Earth during solar cycle 23 (1997–2008). It is noticed that the disturbance content is low for equatorial stations and high for auroral stations. We show that the latitude profile of disturbance exhibits `Knee’ behaviour, with the fluctuation content rising sharply beyond this critical latitude. The threshold latitude beyond which the stations are subject to high geomagnetic disturbance and hence become increasingly susceptible to associated geo-electric hazard is precisely determined near 52° latitude. The pattern of increasing geomagnetic fluctuations however ends around the auroral oval beyond where singular variations are observed.

scholarly journals Predictions of the geomagnetic secular variation based on the ensemble sequential assimilation of geomagnetic field models by dynamo simulations

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Sabrina Sanchez ◽  
Johannes Wicht ◽  
Julien Bärenzung
Keyword(s):  
Magnetic Field ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Wave Number ◽  
Main Magnetic Field ◽  
Candidate Model ◽  
Uncertainty Estimates ◽  
Geomagnetic Field Models ◽  
Dipole Configuration

Abstract The IGRF offers an important incentive for testing algorithms predicting the Earth’s magnetic field changes, known as secular variation (SV), in a 5-year range. Here, we present a SV candidate model for the 13th IGRF that stems from a sequential ensemble data assimilation approach (EnKF). The ensemble consists of a number of parallel-running 3D-dynamo simulations. The assimilated data are geomagnetic field snapshots covering the years 1840 to 2000 from the COV-OBS.x1 model and for 2001 to 2020 from the Kalmag model. A spectral covariance localization method, considering the couplings between spherical harmonics of the same equatorial symmetry and same azimuthal wave number, allows decreasing the ensemble size to about a 100 while maintaining the stability of the assimilation. The quality of 5-year predictions is tested for the past two decades. These tests show that the assimilation scheme is able to reconstruct the overall SV evolution. They also suggest that a better 5-year forecast is obtained keeping the SV constant compared to the dynamically evolving SV. However, the quality of the dynamical forecast steadily improves over the full assimilation window (180 years). We therefore propose the instantaneous SV estimate for 2020 from our assimilation as a candidate model for the IGRF-13. The ensemble approach provides uncertainty estimates, which closely match the residual differences with respect to the IGRF-13. Longer term predictions for the evolution of the main magnetic field features over a 50-year range are also presented. We observe the further decrease of the axial dipole at a mean rate of 8 nT/year as well as a deepening and broadening of the South Atlantic Anomaly. The magnetic dip poles are seen to approach an eccentric dipole configuration.

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS II: Electron Spin Resonance of DPPH Coated on Y1Ba2Cu3Oy as A Probe of Magnetic Field Variations

1991 ◽  
Vol 05 (11) ◽  
pp. 779-787
Author(s):  
K. SUGAWARA ◽  
D.J. BAAR ◽  
Y. SHIOHARA ◽  
S. TANAKA
Keyword(s):  
Magnetic Field ◽  
Temporal Variations ◽  
Zero Field ◽  
High Tc ◽  
Spin Resonance ◽  
Absorption Studies ◽  
Powder Particles ◽  
Increasing Temperature ◽  
Linewidth Broadening ◽  
Magnetic Field Variations

The ESR linewidth (∆H pp ) of DPPH coated on the surface of powder specimens of Y 1 Ba 2 Cu 3 O y has been studied under various magnetic field and temperature conditions. ∆H pp increases substantially with decreasing temperature in the field cooled case, whereas almost no linewidth broadening was found in the zero field cooled case. ∆H pp was found to be sensitive to the applied magnetic field. This effect was very pronounced at temperatures lower than 40 K, but decreased strongly with increasing temperature. The broadening of the resonance lineshape has been attributed to spatial and temporal variations of the fluxon distribution in the powder particles.

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