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.
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 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 radio window is the region of the radio spectrum that penetrate the Earth's atmosphere. Typically, the lower limit of the radio window's range has a value of about 10 MHz ; the best upper limit achievable from optimal terrestrial observation sites is equal to approximately 1 THz.
The Poker Flat Research Range (PFRR) is a launch facility and rocket range for sounding rockets in the U.S. state of Alaska, located on a 5,132-acre (20.77 km2) site at Chatanika, about 30 miles (50 km) northeast of Fairbanks and 1.5 degrees south of the Arctic Circle. More than 1,700 launches have been conducted at the range to study the Earth's atmosphere and the interaction between the atmosphere and the space environment. Areas studied at PFRR include the aurora, plasma physics, the ozone layer, solar proton events, Earth's magnetic field, and ultraviolet radiation. Rockets launched at PFRR have attained an apogee of 930 miles (1,500 km).
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.
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 Geophysical Institute of the University of Alaska Fairbanks conducts research into space physics and aeronomy; atmospheric sciences; snow, ice, and permafrost; seismology; volcanology; and tectonics and sedimentation. It was founded in 1946 by an act of the United States Congress.
Umran Savaş İnan is a Turkish scientist at Koç University and Stanford University in the field of geophysics and very low frequency radio science. İnan was the president of Koç University between 2009 and 2021.
An ionospheric heater, or an ionospheric HF pump facility, is a powerful radio wave transmitter with an array of antennas which is used for research of plasma turbulence, the ionosphere and upper atmosphere.
A double layer is a structure in a plasma consisting of two parallel layers of opposite electrical charge. The sheets of charge, which are not necessarily planar, produce localised excursions of electric potential, resulting in a relatively strong electric field between the layers and weaker but more extensive compensating fields outside, which restore the global potential. Ions and electrons within the double layer are accelerated, decelerated, or deflected by the electric field, depending on their direction of motion.
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.
The Millstone Hill Steerable Antenna, or MISA, is a fully steerable dish antenna, 46 metres (151 ft) in diameter, designed by the Stanford Research Institute (SRI) in 1959. It is currently located at MIT Haystack Observatory in Westford, Massachusetts.
Ariel 2, also known as UK-C, was a British radio astronomy satellite, which was operated by the Science and Engineering Research Council as part of the Ariel programme. It was built in America by Westinghouse Electric, and had a mass at launch of 68 kilograms (150 lb). It was launched in 1964, and became the first satellite to be used for radio astronomy, although the Canadian satellite Alouette 1 was launched 1962 and also did similar radio astronomy observations.
Fast, Affordable, Science and Technology Satellite-Huntsville 01 or FASTSAT-Huntsville 01 of the NASA. FASTSAT-HSV 01 was flying on the STP-S26 mission - a joint activity between NASA and the U.S. Department of Defense Space Test Program, or DoD STP. FASTSAT and all of its six experiments flying on the STP-S26 multi-spacecraft/payload mission have been approved by the Department of Defense Space and Experiments Review Board (USA-220).
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.
Waves is an experiment on the Juno spacecraft for studying radio and plasma waves. It is part of a collection of various types of instruments and experiments on the spacecraft; Waves is oriented towards understanding fields and particles in the Jupiter's magnetosphere. Waves is on board the uncrewed Juno spacecraft, which was launched in 2011 and arrived at Jupiter in the summer of 2016. The major focus of study for Waves is Jupiter's magnetosphere, which if could be seen from Earth would be about twice the size of a full moon. The magnetosphere has a tear drop shape, and that tail extends away from the Sun by at least 5 AU. The Waves instrument is designed to help understand the interaction between Jupiter's atmosphere, its magnetic field, its magnetosphere, and to understand Jupiter's auroras. It is designed to detect radio frequencies from 50 Hz up to 40,000,000 Hz (40 MHz), and magnetic fields from 50 Hz to 20,000 Hz (20 kHz). It has two main sensors: a dipole antenna and a magnetic search coil. The dipole antenna has two whip antennas that extend 2.8 meters and are attached to the main body of the spacecraft. This sensor has been compared to a rabbit-ear TV antenna. The search coil is overall a Mu-metal rod 15 cm (6 in) in length with a fine copper wire wound 10,000 times around it. There are also two frequency receivers that each cover certain bands. Data handling is done by two radiation-hardened systems on a chip. The data handling units are located inside the Juno Radiation Vault. Waves is allocated 410 Mbits of data per science orbit.
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.
