180 research outputs found
HelsinkiNet - a collaborative seismological research network of the Institute of Seismology, and the City of Helsinki
Non peer reviewe
HelsinkiNet - a collaborative seismological research network of the Institute of Seismology, and the City of Helsinki
Non peer reviewe
Geomagnetism review 2019
A review of the BGS's Geomagnetism Science Capability activities in 2019
Contactless measurement of electric current using magnetic sensors
We review recent advances in magnetic sensors for DC/AC current transducers, especially novel AMR sensors and integrated fluxgates, and we make critical comparison of their properties. Most contactless electric current transducers use magnetic cores to concentrate the flux generated by the measured current and to shield the sensor against external magnetic fields. In order to achieve this, the magnetic core should be massive. We present coreless current transducers which are lightweight, linear and free of hysteresis and remanence. We also show how to suppress their weak point: crosstalk from external currents and magnetic fields
Progress in space weather modeling in an operational environment
This paper aims at providing an overview of latest advances in space weather modeling in an operational environment in Europe,
including both the introduction of new models and improvements to existing codes and algorithms that address the broad range of space weatherâs prediction requirements from the Sun to the Earth. For each case, we consider the modelâs input data, the output
parameters, products or services, its operational status, and whether it is supported by validation results, in order to build a solid basis for future developments. This work is the output of the Sub Group 1.3 ââImprovement of operational modelsââ of the European Cooperation in Science and Technology (COST) Action ES0803 ââDeveloping Space Weather Products and services in Europeââ and therefore this review focuses on the progress achieved by European research teams involved in the action
Anthropogenic Space Weather
Anthropogenic effects on the space environment started in the late 19th
century and reached their peak in the 1960s when high-altitude nuclear
explosions were carried out by the USA and the Soviet Union. These explosions
created artificial radiation belts near Earth that resulted in major damages to
several satellites. Another, unexpected impact of the high-altitude nuclear
tests was the electromagnetic pulse (EMP) that can have devastating effects
over a large geographic area (as large as the continental United States). Other
anthropogenic impacts on the space environment include chemical release ex-
periments, high-frequency wave heating of the ionosphere and the interaction of
VLF waves with the radiation belts. This paper reviews the fundamental physical
process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure
Review of Environmental Monitoring by Means of Radio Waves in the Polar Regions: From Atmosphere to Geospace
The Antarctic and Arctic regions are Earth's open windows to outer space. They provide unique opportunities for investigating the troposphereâthermosphereâionosphereâplasmasphere system at high latitudes, which is not as well understood as the mid- and low-latitude regions mainly due to the paucity of experimental observations. In addition, different neutral and ionised atmospheric layers at high latitudes are much more variable compared to lower latitudes, and their variability is due to mechanisms not yet fully understood. Fortunately, in this new millennium the observing infrastructure in Antarctica and the Arctic has been growing, thus providing scientists with new opportunities to advance our knowledge on the polar atmosphere and geospace. This review shows that it is of paramount importance to perform integrated, multi-disciplinary research, making use of long-term multi-instrument observations combined with ad hoc measurement campaigns to improve our capability of investigating atmospheric dynamics in the polar regions from the troposphere up to the plasmasphere, as well as the coupling between atmospheric layers. Starting from the state of the art of understanding the polar atmosphere, our survey outlines the roadmap for enhancing scientific investigation of its physical mechanisms and dynamics through the full exploitation of the available infrastructures for radio-based environmental monitoring
Low frequency geomagnetic fluctuations (.04 to 25 Hz) on land and on the floor of Monterey Bay
A coil antenna consisting of approximately 6000 turns
of copper wire was utilized to measure the horizontal component
of fluctuations of the earth's magnetic field on the
floor of Monterey Bay in water depth of approximately 50
meters. The results indicate that the power spectral density
of the fluctuations varies from 10nTÂČ/Hz at 0.04 Hz to
10Ëâ¶nTÂČ/Hz at 25 Hz, a monotonic decrease of about 6 dB/
octave, except in the 8-20 Hz region where the Schumann
resonances occur. While the sensitivity of the equipment
was insufficient to measure the vertical component of the
fluctuation we can put an upper limit of 10ËÂłnTÂČ/Hz at 1 Hz
and 10Ëâ¶(nT)ÂČ/Hz at 10 Hz on the magnitude of this component.
The same sensor was also used to measure various components
of the field fluctuations at a remote land' site
(Chew's Ridge). In the frequency range observed the general
shape of the spectra was similar to those obtained at
sea. However, a strong azimuthal variation at certain
frequencies was noted in the land data. The possibility
that these directional signals are of man made origin
cannot be excluded at this time.http://archive.org/details/lowfrequencygeom00mcdeLieutenant Commander, United States NavyLieutenant, United States NavyApproved for public release; distribution is unlimited
Progress in space weather modeling in an operational environment
YesThis paper aims at providing an overview of latest advances in space weather modeling in an operational environment in Europe, including both the introduction of new models and improvements to existing codes and algorithms that address the broad range of space weather's prediction requirements from the Sun to the Earth. For each case, we consider the model's input data, the output parameters, products or services, its operational status, and whether it is supported by validation results, in order to build a solid basis for future developments. This work is the output of the Sub Group 1.3 "Improvement of operational models'' of the European Cooperation in Science and Technology (COST) Action ES0803 "Developing Space Weather Products and services in Europe'' and therefore this review focuses on the progress achieved by European research teams involved in the action
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