Related Research Articles
The ionosphere is the ionized part of the upper atmosphere of Earth, from about 48 km (30 mi) to 965 km (600 mi) above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on Earth. It also affects GPS signals that travel through this layer.
An aurora , also commonly known as the northern lights or southern lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions. Auroras display dynamic patterns of brilliant lights that appear as curtains, rays, spirals, or dynamic flickers covering the entire sky.
The High-frequency Active Auroral Research Program (HAARP) is a University of Alaska Fairbanks program which researches the ionosphere – the highest, ionized part of Earth's atmosphere.
Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the varying conditions within the Solar System and its heliosphere. This includes the effects of the solar wind, especially on the Earth's magnetosphere, ionosphere, thermosphere, and exosphere. Though physically distinct, space weather is analogous to the terrestrial weather of Earth's atmosphere. The term "space weather" was first used in the 1950s and popularized in the 1990s. Later, it prompted research into "space climate", the large-scale and long-term patterns of space weather.
A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth's magnetosphere caused by a solar wind shock wave.
A whistler is a very low frequency (VLF) electromagnetic (radio) wave generated by lightning. Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, with maximum frequencies usually at 3 kHz to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strikes where the impulse travels along the Earth's magnetic field lines from one hemisphere to the other. They undergo dispersion of several kHz due to the slower velocity of the lower frequencies through the plasma environments of the ionosphere and magnetosphere. Thus they are perceived as a descending tone which can last for a few seconds. The study of whistlers categorizes them into Pure Note, Diffuse, 2-Hop, and Echo Train types.
The Swedish Institute of Space Physics is a Swedish government agency. The institute's primary task is to carry out basic research, education and associated observatory activities in space physics, space technology and atmospheric physics.
The HIPASObservatory was a research facility, built to study the ionosphere and its influence on radio communications. It was located 25 miles east of Fairbanks, Alaska in the Fairbanks North Star Borough area.
EISCAT operates three incoherent scatter radar systems in Northern Scandinavia and Svalbard. The facilities are used to study the interaction between the Sun and the Earth as revealed by disturbances in the ionosphere and magnetosphere.
Incoherent scattering is a type of scattering phenomenon in physics. The term is most commonly used when referring to the scattering of an electromagnetic wave by random fluctuations in a gas of particles.
A Birkeland current is a set of electrical currents that flow along geomagnetic field lines connecting the Earth's magnetosphere to the Earth's high latitude ionosphere. In the Earth's magnetosphere, the currents are driven by the solar wind and interplanetary magnetic field and by bulk motions of plasma through the magnetosphere. The strength of the Birkeland currents changes with activity in the magnetosphere. Small scale variations in the upward current sheets accelerate magnetospheric electrons which, when they reach the upper atmosphere, create the Auroras Borealis and Australis.
The Super Dual Auroral Radar Network (SuperDARN) is an international scientific radar network consisting of 35 high frequency (HF) radars located in both the Northern and Southern Hemispheres. SuperDARN radars are primarily used to map high-latitude plasma convection in the F region of the ionosphere, but the radars are also used to study a wider range of geospace phenomena including field aligned currents, magnetic reconnection, geomagnetic storms and substorms, magnetospheric MHD waves, mesospheric winds via meteor ionization trails, and interhemispheric plasma convection asymmetries. The SuperDARN collaboration is composed of radars operated by JHU/APL, Virginia Tech, Dartmouth College, the Geophysical Institute at the University of Alaska Fairbanks, the Institute of Space and Atmospheric Studies at the University of Saskatchewan, the University of Leicester, Lancaster University, La Trobe University, the Solar-Terrestrial Environment Laboratory at Nagoya University, the British Antarctic Survey and the Institute for Space Astrophysics and Planetology.
The magnetosphere of Jupiter is the cavity created in the solar wind by Jupiter's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973.
Canadian Geospace Monitoring (CGSM) is a Canadian space science program that was initiated in 2005. CGSM is funded primarily by the Canadian Space Agency, and consists of networks of imagers, meridian scanning photometers, riometers, magnetometers, digital ionosondes, and High Frequency SuperDARN radars. The overarching objective of CGSM is to provide synoptic observations of the spatio-temporal evolution of the ionospheric thermodynamics and electrodynamics at auroral and polar latitudes over a large region of Canada.
Tor Hagfors was a Norwegian scientist, radio astronomer, radar expert and a pioneer in the studies of the interactions between electromagnetic waves and plasma. In the early 1960s he was one of a handful of pioneering theorists that independently developed a theory that explained the scattering of radio waves by the free electrons in a plasma and applied the result to the ionosphere. He became founding director of the new EISCAT facilities that were then under construction in 1975, by which time he already been director at most of the other incoherent scatter radar facilities in the world. The asteroid 1985 VD1 is named 7279 Hagfors after him.
This is an index to articles about terms used in discussion of radio propagation.
The Jicamarca Radio Observatory (JRO) is the equatorial anchor of the Western Hemisphere chain of Incoherent Scatter Radar (ISR) observatories extending from Lima, Peru to Søndre Strømfjord, Greenland. JRO is the premier scientific facility in the world for studying the equatorial ionosphere. The observatory is about half an hour drive inland (east) from Lima and 10 km from the Central Highway. The magnetic dip angle is about 1°, and varies slightly with altitude and year. The radar can accurately determine the direction of the Earth's magnetic field (B) and can be pointed perpendicular to B at altitudes throughout the ionosphere. The study of the equatorial ionosphere is rapidly becoming a mature field due, in large part, to the contributions made by JRO in radio science.
RAX-2 is a CubeSat satellite built as a collaboration between SRI International and students at the University of Michigan College of Engineering. It is the second spacecraft in the RAX mission. The RAX-1 mission ended after approximately two months of operation due to a gradual degradation of the solar panels that ultimately resulted in a loss of power. RAX team members applied the lessons learned from RAX-1 to the design of a second flight unit, RAX-2, which performs the same mission concept of RAX-1 with improved bus performance and additional operational modes. Science measurements are enhanced through interactive experiments with high power ionospheric heaters where FAI will be generated on demand.
The Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) is an astronomical observatory operated by the Sodankylä Geophysical Observatory on behalf of Oulu University. It is located at Kilpisjärvi, Enontekiö near the border with Norway. It comprises two LOFAR-derived radio telescope systems and is capable of observing at HF and VHF radio frequencies. It is used for atmospheric, near-Earth space and astronomical research. KAIRA uses LOFAR phased-array antennas and digital signal-processing hardware. The phased array configuration has no moving parts and with digital control, allows KAIRA to quickly scan the sky, giving KAIRA a large field of view. KAIRA can produce a continuous all-sky image of the radio transparency of ionosphere, using cosmic radio noise for "illumination" (riometry). KAIRA can also obtain electron density profiles in the atmosphere. This allows the study of the interaction of the solar wind with the atmosphere, such as in aurora borealis and other space weather phenomena. In addition to near-space imaging, the use of KAIRA has been demonstrated for long-baseline interferometry observations of pulsars.
Dynamics Explorer 1 was a NASA high-altitude mission, launched on 3 August 1981, and terminated on 28 February 1991. It consisted of two satellites, DE-1 and DE-2, whose purpose was to investigate the interactions between plasmas in the magnetosphere and those in the ionosphere. The two satellites were launched together into polar coplanar orbits, which allowed them to simultaneously observe the upper and lower parts of the atmosphere.
References
- 1 2 Powerful electromagnetic waves for active environmental research in geospace, by T. B. Leyser and A. Y. Wong (Reviews of Geophysics, Vol. 47, RG1001, 2009).
- ↑ "HAARP Fact Sheet". Archived from the original on 2009-10-07. Retrieved 2009-10-07.
- ↑ "BasicInfo". e7.eiscat.se.
- ↑ "abstract/s19.txt". www.kurasc.kyoto-u.ac.jp.
- ↑ "SPEAR (Space Plasma Exploration by Active Radar)". spear.unis.no.