Ionosphere - Knowledge (XXG)

2387:

most interference to the amateurs, and was happy to see them on the road to a hoped - for extinction. From the amateurs' point of view, their development of the shortwave spectrum began less as a love affair than a shotgun marriage. However, all that would change...It took several years before experimenters ventured above 2-3 mc. and started to understand such things as shortwave propagation and directionality. The short waves, as they were called, were surrounded with mystery...Also in 1928 Radio News publisher Hugo Gernsback began shortwave broadcasting on 9700 kc. from his station, WRNY, New York, using the call W2XAL. "A reader in New South Wales, Aus- tralia," reported Gernsback, "writes us that while he was writing his letter he was listening to WRNY's short-wave transmitter, 2XAL, on a three-tube set; and had to turn down the volume, otherwise he would wake up his family. All this at a distance of some 10,000 miles! Yet 2XAL ...uses less than 500 watts; a quite negligible amount of power. "6...The 1930s were the golden age of shortwave broadcasting...Shortwave also facilitated communication with people in remote areas. Amateur radio became a basic ingredient of all expeditions...The term shortwave was generally taken to refer to anything above 1.5 mc., without upper limit...",

2185:(Another part of our theory about which doubt may arise is the assumption that the agents of terrestrial magnetic force have their source exclusively in the interior of the Earth. If the immediate causes should be sought entirely or in part outside , then we can — in so far as we exclude baseless fantasies and we want to restrict ourselves to the scientifically known — consider only galvanic currents. Atmospheric air is not a conductor of such currents; empty space also is not: thus our knowledge fails us when we seek a carrier for galvanic currents in the upper regions . Only the enigmatic phenomena of the northern lights — in which by all appearances electricity in motion plays a major role — prohibits us from simply denying the possibility of such currents just on account of that ignorance, and in any case it remains interesting to investigate how the magnetic effect resulting from would manifest itself on the Earth's surface.) 1644:. An ionosonde sweeps a range of frequencies, usually from 0.1 to 30 MHz, transmitting at vertical incidence to the ionosphere. As the frequency increases, each wave is refracted less by the ionization in the layer, and so each penetrates further before it is reflected. Eventually, a frequency is reached that enables the wave to penetrate the layer without being reflected. For ordinary mode waves, this occurs when the transmitted frequency just exceeds the peak plasma, or critical, frequency of the layer. Tracings of the reflected high frequency radio pulses are known as ionograms. Reduction rules are given in: "URSI Handbook of Ionogram Interpretation and Reduction", edited by 3553: 1222:. During the first half of the 20th century it was widely used for transoceanic telephone and telegraph service, and business and diplomatic communication. Due to its relative unreliability, shortwave radio communication has been mostly abandoned by the telecommunications industry, though it remains important for high-latitude communication where satellite-based radio communication is not possible. Shortwave broadcasting is useful in crossing international boundaries and covering large areas at low cost. Automated services still use 1548: 703: 517: 599:, ionization can reach unusually high levels in the D-region over high and polar latitudes. Such very rare events are known as Polar Cap Absorption (or PCA) events, because the increased ionization significantly enhances the absorption of radio signals passing through the region. In fact, absorption levels can increase by many tens of dB during intense events, which is enough to absorb most (if not all) transpolar HF radio signal transmissions. Such events typically last less than 24 to 48 hours. 911: 3565: 1104:(3–30 kHz) signals will be reflected by the D layer instead of the E layer, where the increased atmospheric density will usually increase the absorption of the wave and thus dampen it. As soon as the X-rays end, the sudden ionospheric disturbance (SID) or radio black-out steadily declines as the electrons in the D-region recombine rapidly and propagation gradually returns to pre-flare conditions over minutes to hours depending on the solar flare strength and frequency. 1607:), involve high power radio transmitters to modify the properties of the ionosphere. These investigations focus on studying the properties and behavior of ionospheric plasma, with particular emphasis on being able to understand and use it to enhance communications and surveillance systems for both civilian and military purposes. HAARP was started in 1993 as a proposed twenty-year experiment, and is currently active near Gakona, Alaska. 1448: 497: 425:, in which a free electron is "captured" by a positive ion. Recombination occurs spontaneously, and causes the emission of a photon carrying away the energy produced upon recombination. As gas density increases at lower altitudes, the recombination process prevails, since the gas molecules and ions are closer together. The balance between these two processes determines the quantity of ionization present. 31: 1028: 850: 525: 3601: 1010:) (100–130 km (60–80 mi) altitude). Resulting from this current is an electrostatic field directed west–east (dawn–dusk) in the equatorial day side of the ionosphere. At the magnetic dip equator, where the geomagnetic field is horizontal, this electric field results in an enhanced eastward current flow within ± 3 degrees of the magnetic equator, known as the 3625: 3577: 3613: 688:

high signal levels are often reached. The skip distances are generally around 1,640 km (1,020 mi). Distances for one hop propagation can be anywhere from 900 to 2,500 km (560 to 1,550 mi). Multi-hop propagation over 3,500 km (2,200 mi) is also common, sometimes to distances of 15,000 km (9,300 mi) or more.

3589: 2386:

Quote: "...In addition to having to obtain licenses - a constraint to which they adapted only slowly - the amateurs were, with some exceptions, restricted to the range below 200 meters (that is, above 1500 kc.), bands that were largely unexplored and thought to be of little value. The navy attributed

1610:

The SuperDARN radar project researches the high- and mid-latitudes using coherent backscatter of radio waves in the 8 to 20 MHz range. Coherent backscatter is similar to Bragg scattering in crystals and involves the constructive interference of scattering from ionospheric density irregularities.

1230:

hobbyists for private recreational contacts and to assist with emergency communications during natural disasters. Armed forces use shortwave so as to be independent of vulnerable infrastructure, including satellites, and the low latency of shortwave communications make it attractive to stock traders,

579:

are significantly attenuated within the D layer, as the passing radio waves cause electrons to move, which then collide with the neutral molecules, giving up their energy. Lower frequencies experience greater absorption because they move the electrons farther, leading to greater chance of collisions.

247:

We have in quite recent years seen the universal adoption of the term 'stratosphere'..and..the companion term 'troposphere'... The term 'ionosphere', for the region in which the main characteristic is large scale ionisation with considerable mean free paths, appears appropriate as an addition to

2350:

Speaking of wireless telegraphy, Heaviside speculated about the propagation of Hertzian (radio) waves through the atmosphere. From p. 215: "There may possibly be a sufficiently conducting layer in the upper air. If so, the waves will, so to speak, catch on to it more or less. Then the guidance will

945:

layer daytime ion production is higher in the summer, as expected, since the Sun shines more directly on the Earth. However, there are seasonal changes in the molecular-to-atomic ratio of the neutral atmosphere that cause the summer ion loss rate to be even higher. The result is that the increase in

687:

very exciting when long-distance propagation paths that are generally unreachable "open up" to two-way communication. There are multiple causes of sporadic-E that are still being pursued by researchers. This propagation occurs every day during June and July in northern hemisphere mid-latitudes when

634:

layer can reflect frequencies up to 50 MHz and higher. The vertical structure of the E layer is primarily determined by the competing effects of ionization and recombination. At night the E layer weakens because the primary source of ionization is no longer present. After sunset an increase in

1103:

can occur that hit the sunlit side of Earth with hard X-rays. The X-rays penetrate to the D-region, releasing electrons that rapidly increase absorption, causing a high frequency (3–30 MHz) radio blackout that can persist for many hours after strong flares. During this time very low frequency

1703:

signal tangentially scrapes the Earth, passing through the atmosphere, and is received by a Low Earth Orbit (LEO) satellite. As the signal passes through the atmosphere, it is refracted, curved and delayed. An LEO satellite samples the total electron content and bending angle of many such signal

1259:

is less than unity. Hence, the electromagnetic "ray" is bent away from the normal rather than toward the normal as would be indicated when the refractive index is greater than unity. It can also be shown that the refractive index of a plasma, and hence the ionosphere, is frequency-dependent, see

1180:

In 1925, C. T. R. Wilson proposed a mechanism by which electrical discharge from lightning storms could propagate upwards from clouds to the ionosphere. Around the same time, Robert Watson-Watt, working at the Radio Research Station in Slough, UK, suggested that the ionospheric sporadic E layer

504:

At night the F layer is the only layer of significant ionization present, while the ionization in the E and D layers is extremely low. During the day, the D and E layers become much more heavily ionized, as does the F layer, which develops an additional, weaker region of ionisation known as the

1118:

Associated with solar flares is a release of high-energy protons. These particles can hit the Earth within 15 minutes to 2 hours of the solar flare. The protons spiral around and down the magnetic field lines of the Earth and penetrate into the atmosphere near the magnetic poles increasing the

1247:

at the same frequency as the radio wave. Some of the radio-frequency energy is given up to this resonant oscillation. The oscillating electrons will then either be lost to recombination or will re-radiate the original wave energy. Total refraction can occur when the collision frequency of the

714:

or region, also known as the Appleton–Barnett layer, extends from about 150 km (93 mi) to more than 500 km (310 mi) above the surface of Earth. It is the layer with the highest electron density, which implies signals penetrating this layer will escape into space. Electron

803:

Models are usually expressed as computer programs. The model may be based on basic physics of the interactions of the ions and electrons with the neutral atmosphere and sunlight, or it may be a statistical description based on a large number of observations or a combination of physics and

1812:, especially in older literature). The Earth's magnetic field is measured around the planet by many observatories. The data retrieved is processed and turned into measurement indices. Daily measurements for the entire planet are made available through an estimate of the 1743:

F10.7 and R12 are two indices commonly used in ionospheric modelling. Both are valuable for their long historical records covering multiple solar cycles. F10.7 is a measurement of the intensity of solar radio emissions at a frequency of 2800 MHz made using a ground

225:

and his team demonstrated the influence of sunlight on radio wave propagation, revealing that short waves became weak or inaudible while long waves steadied during the eclipse, thus contributing to the understanding of the ionosphere's role in radio transmission.

1663:

radars operate above the critical frequencies. Therefore, the technique allows probing the ionosphere, unlike ionosondes, also above the electron density peaks. The thermal fluctuations of the electron density scattering the transmitted signals lack

950:

ionization is actually lower in the local summer months. This effect is known as the winter anomaly. The anomaly is always present in the northern hemisphere, but is usually absent in the southern hemisphere during periods of low solar activity.

832:, and in situ instruments on several satellites and rockets. IRI is updated yearly. IRI is more accurate in describing the variation of the electron density from bottom of the ionosphere to the altitude of maximum density than in describing the 1214:" propagation, has been used since the 1920s to communicate at international or intercontinental distances. The returning radio waves can reflect off the Earth's surface into the sky again, allowing greater ranges to be achieved with multiple 678:

E-layer) is characterized by small, thin clouds of intense ionization, which can support reflection of radio waves, frequently up to 50 MHz and rarely up to 450 MHz. Sporadic-E events may last for just a few minutes to many hours.

584:, particularly at 10 MHz and below, with progressively less absorption at higher frequencies. This effect peaks around noon and is reduced at night due to a decrease in the D layer's thickness; only a small part remains due to 214:, limiting their operations to frequencies above 1.5 MHz (wavelength 200 meters or smaller). The government thought those frequencies were useless. This led to the discovery of HF radio propagation via the ionosphere in 1923. 2183:"§ 36. Ein anderer Theil unserer Theorie, über welchen ein Zweifel Statt finden kann, ist die Voraussetzung, … zu untersuchen, wie die aus denselben hervorgehende magnetische Wirkung auf der Erdoberfläche sich gestalten würde." 3050: 1724: 1210:) radio waves, the ionosphere can reflect radio waves directed into the sky back toward the Earth. Radio waves directed at an angle into the sky can return to Earth beyond the horizon. This technique, called "skip" or " 2180:

Gauss speculated that magnetic forces might be generated not only by electrical currents flowing through the Earth's interior but also by some sort of electrical current(s) flowing through the atmosphere. From p. 50:

1170:. These so-called "whistler" mode waves can interact with radiation belt particles and cause them to precipitate onto the ionosphere, adding ionization to the D-region. These disturbances are called "lightning-induced 1391: 2034: 626:). Normally, at oblique incidence, this layer can only reflect radio waves having frequencies lower than about 10 MHz and may contribute a bit to absorption on frequencies above. However, during intense 1751:

However, both indices are only indirect indicators of solar ultraviolet and X-ray emissions, which are primarily responsible for causing ionization in the Earth's upper atmosphere. We now have data from the

1185:) appeared to be enhanced as a result of lightning but that more work was needed. In 2005, C. Davis and C. Johnson, working at the Rutherford Appleton Laboratory in Oxfordshire, UK, demonstrated that the E 617:

is the middle layer, 90 to 150 km (56 to 93 mi) above the surface of the Earth. Ionization is due to soft X-ray (1–10 nm) and far ultraviolet (UV) solar radiation ionization of molecular

312:

On July 26, 1963, the first operational geosynchronous satellite Syncom 2 was launched. On board radio beacons on this satellite (and its successors) enabled – for the first time – the measurement of

3023:

Günzkofer, F.; Pokhotelov, D.; Stober, G.; et al. (2022-09-25). "Determining the Origin of Tidal Oscillations in the Ionospheric Transition Region With EISCAT Radar and Global Simulation Data".

1323: 1435:

is the frequency below which a radio wave fails to penetrate a layer of the ionosphere at the incidence angle required for transmission between two specified points by refraction from the layer.

781:

is a mathematical description of the ionosphere as a function of location, altitude, day of year, phase of the sunspot cycle and geomagnetic activity. Geophysically, the state of the ionospheric

413:

at these frequencies contain sufficient energy to dislodge an electron from a neutral gas atom or molecule upon absorption. In this process the light electron obtains a high velocity so that the

3078: 316:(TEC) variation along a radio beam from geostationary orbit to an earth receiver. (The rotation of the plane of polarization directly measures TEC along the path.) Australian geophysicist 1668:, which gave the technique its name. Their power spectrum contains information not only on the density, but also on the ion and electron temperatures, ion masses and drift velocities. 1871:

includes an ionosphere that ranges from about 880 to 1,300 km (550 to 810 mi) in altitude and contains carbon compounds. Ionospheres have also been observed at

2209: 2341: 1414: 3435: 2981: 1177:

Additional ionization can also occur from direct heating/ionization as a result of huge motions of charge in lightning strikes. These events are called early/fast.

1148:

During a geomagnetic storm the F₂ layer will become unstable, fragment, and may even disappear completely. In the Northern and Southern polar regions of the Earth

2004: 1604: 1218:. This communication method is variable and unreliable, with reception over a given path depending on time of day or night, the seasons, weather, and the 11-year 990:

oscillations in the lower ionosphere move plasma up and across the magnetic field lines. This sets up a sheet of electric current in the E region which, with the

195:

of the ionosphere which bears his name. Heaviside's proposal included means by which radio signals are transmitted around the Earth's curvature. Also in 1902,

1166:

Lightning can cause ionospheric perturbations in the D-region in one of two ways. The first is through VLF (very low frequency) radio waves launched into the

340:

that surrounds the Earth, stretching from a height of about 50 km (30 mi) to more than 1,000 km (600 mi). It exists primarily due to

140:

postulated that an electrically conducting region of the atmosphere could account for observed variations of Earth's magnetic field. Sixty years later,

1335:

The Maximum Usable Frequency (MUF) is defined as the upper frequency limit that can be used for transmission between two points at a specified time.

1189:

layer was indeed enhanced as a result of lightning activity. Their subsequent research has focused on the mechanism by which this process can occur.

1929: 960: 3101: 3074: 1279:

of the ionosphere, then the electrons cannot respond fast enough, and they are not able to re-radiate the signal. It is calculated as shown below:

1716: 2502: 2388: 1341: 994:

magnetic field, forces ionization up into the F layer, concentrating at ± 20 degrees from the magnetic equator. This phenomenon is known as the

642:

or simply the Heaviside layer. Its existence was predicted in 1902 independently and almost simultaneously by the American electrical engineer

180:

has contested this, however, based on theoretical and experimental work. However, Marconi did achieve transatlantic wireless communications in

1119:

ionization of the D and E layers. PCA's typically last anywhere from about an hour to several days, with an average of around 24 to 36 hours.

3269: 3197: 3178: 3131: 2745: 2077: 1735:

In empirical models of the ionosphere such as Nequick, the following indices are used as indirect indicators of the state of the ionosphere.

460:

is tipped away from the Sun, thus there is less received solar radiation. Radiation received also varies with geographical location (polar,

3655: 1789:-index uses a semi-logarithmic scale from 0 to 9 to measure the strength of the horizontal component of the geomagnetic field. The Boulder 813: 3428: 2304: 3006: 1919: 805: 2952: 808:(IRI), which is based on data and specifies the four parameters just mentioned. The IRI is an international project sponsored by the 3342: 3159: 2778: 2654: 2152: 2029: 1075: 1006:

The worldwide solar-driven wind results in the so-called Sq (solar quiet) current system in the E region of the Earth's ionosphere (

897: 417:

of the created electronic gas is much higher (of the order of thousand K) than the one of ions and neutrals. The reverse process to

218: 2362: 2196:

Scientific Memoirs, Selected from the Transactions of Foreign Academies of Science and Learned Societies, and from Foreign Journals

278:

first measured the height and density of the ionosphere. This permitted the first complete theory of short-wave radio propagation.

2144: 540:

The D layer is the innermost layer, 48 to 90 km (30 to 56 mi) above the surface of the Earth. Ionization here is due to

371:, the atmosphere is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive 1593: 1794: 1614:

Scientists are also examining the ionosphere by the changes to radio waves, from satellites and stars, passing through it. The

1958: 754:

ions decreases and lighter ions such as hydrogen and helium become dominant. This region above the F layer peak and below the

1501: 1285: 1094: 1053: 875: 471: 3421: 3367: 3398: 1484:

There are a number of models used to understand the effects of the ionosphere on global navigation satellite systems. The

1251:

A qualitative understanding of how an electromagnetic wave propagates through the ionosphere can be obtained by recalling

428:

Ionization depends primarily on the Sun and its Extreme Ultraviolet (EUV) and X-ray irradiance which varies strongly with

3543: 2974: 2302:

Fessenden and Marconi: Their Differing Technologies and Transatlantic Experiments During the First Decade of this Century

2168:

Gauss, Carl Friedrich (1839). "Allgemeine Theorie des Erdmagnetismus ". In Gauss, Carl Friedrich; Weber, Wilhelm (eds.).

1748:. R12 is a 12 months average of daily sunspot numbers. The two indices have been shown to be correlated with each other. 639: 614: 608: 448:

events that can increase ionization in the polar regions. Thus the degree of ionization in the ionosphere follows both a

192: 3650: 2644: 1999: 1525: 829: 2524: 1586: 1272: 1049: 871: 809: 655: 1832:

Objects in the Solar System that have appreciable atmospheres (i.e., all of the major planets and many of the larger

1535:

uses plasma contactors and the ionosphere as parts of a circuit to extract energy from the Earth's magnetic field by

1038: 860: 513:

layer persists by day and night and is the main region responsible for the refraction and reflection of radio waves.

440:

and accompanying increases in EUV and X-ray irradiance, particularly during episodic magnetic eruptions that include

261: 145: 2384:

worldradiohistory.com: Broadcast listening in the pioneer days of radio on the short waves, 1923 1945 Jerome S. Berg

635:

the height of the E layer maximum increases the range to which radio waves can travel by reflection from the layer.

2069: 2057: 1578: 3126:. IEE Electromagnetic Waves Series #31. London, UK: Peter Peregrinus Ltd/The Institution of Electrical Engineers. 1057: 1042: 933:

produces rough echo traces, seen predominantly at night and at higher latitudes, and during disturbed conditions.

879: 864: 168:

and a power of 100 times more than any radio signal previously produced. The message received was three dits, the

1978: 1973: 1924: 1681: 1536: 1007: 983: 422: 706:

Main gases of the ionosphere (about 50 km; 31 miand above on this chart) vary considerably by altitude

1944: 1845: 1215: 684: 445: 3377: 2114: 1800:

The geomagnetic activity levels of the Earth are measured by the fluctuation of the Earth's magnetic field in

1547: 468:, and equatorial regions). There are also mechanisms that disturb the ionosphere and decrease the ionization. 3388: 1248:

ionosphere is less than the radio frequency, and if the electron density in the ionosphere is great enough.

836:(TEC). Since 1999 this model is "International Standard" for the terrestrial ionosphere (standard TS16457). 702: 222: 211: 109: 2554: 2221:"Carl Friedrich Gauss – General Theory of Terrestrial Magnetism – a revised translation of the German text" 3393: 2400: 1968: 1479: 1271:

is the limiting frequency at or below which a radio wave is reflected by an ionospheric layer at vertical

1171: 833: 680: 581: 516: 313: 181: 89: 921:

allow deducing, via computation, the true shape of the different layers. Nonhomogeneous structure of the

3557: 3360: 3098: 1528: 1120: 1011: 643: 436:

active regions there are on the Sun at any one time. Sunspot active regions are the source of increased

317: 309:

satellites in 1969 and 1971, further AEROS-A and -B in 1972 and 1975, all for measuring the ionosphere.

196: 157: 572:. Recombination rates are high in the D layer, so there are many more neutral air molecules than ions. 352: 152:) using a 152.4 m (500 ft) kite-supported antenna for reception. The transmitting station in 910: 3320: 3223: 2700: 2609: 2498: 2445: 2383: 2232: 1853: 1113: 320:

from 1969 onwards was using this technique to monitor the atmosphere above Australia and Antarctica.

137: 1709: 1652:, Elsevier Amsterdam, 1961 (translations into Chinese, French, Japanese and Russian are available). 3645: 3629: 3564: 3444: 2803: 2019: 1939: 1868: 1837: 1677: 1665: 1645: 1261: 716: 85: 3617: 3605: 3249: 2911: 2716: 2463: 2405: 2203: 2009: 1669: 1660: 1570: 1268: 821: 651: 596: 528: 267: 230: 1141:

Geomagnetic storms and ionospheric storms are temporary and intense disturbances of the Earth's

2427:

The letter, dated 8 November 1926, was addressed to the Secretary of the Radio Research Board.

1560:

Scientists explore the structure of the ionosphere by a wide variety of methods. They include:

1512:

broadcasts 3 coefficients to compute the effective ionization level, which is then used by the

3338: 3265: 3193: 3174: 3155: 3127: 2862: 2823: 2741: 2650: 2625: 2283: 2191: 2148: 2073: 1833: 1720: 1692: 1673: 1615: 1582: 1136: 1132: 959: 825: 797: 766: 376: 290:

has developed a theory of electromagnetic wave propagation in plasmas such as the ionosphere.

279: 207: 141: 117: 3380:

Layman Level Explanations Of "Seemingly" Mysterious 160 Meter (MF/HF) Propagation Occurrences

2841:

Wu, Tsung-Yu; Liu, Jann-Yenq; Chang, Loren C.; Lin, Chien-Hung; Chiu, Yi-Chung (2021-07-19).

2576: 2301: 2169: 1399: 3581: 3328: 3284: 3239: 3231: 3032: 2903: 2870: 2854: 2815: 2708: 2617: 2453: 2275: 2240: 1599:

special receivers to detect how the reflected waves have changed from the transmitted waves.

1432: 1417: 1276: 1256: 1252: 991: 930: 782: 647: 306: 253: 239: 188: 105: 45: 1760:

from the Sun, a parameter more closely related to the ionization levels in the ionosphere.

719:(UV, 10–100 nm) radiation ionizing atomic oxygen. The F layer consists of one layer (F 3105: 2944: 2308: 2098: 1880: 1745: 1223: 1123:

can also release energetic protons that enhance D-region absorption in the polar regions.

437: 429: 402: 287: 283: 3324: 3227: 2843:"Equatorial ionization anomaly response to lunar phase and stratospheric sudden warming" 2704: 2613: 2449: 2236: 2093: 3569: 2875: 1705: 1696: 1240: 740: 589: 384: 363:, followed by the mesosphere. In the stratosphere incoming solar radiation creates the 1704:

paths as it watches the GNSS satellite rise or set behind the Earth. Using an Inverse

1447: 675: 286:

researched the topic of radio propagation of very long radio waves in the ionosphere.

176:. To reach Newfoundland the signal would have to bounce off the ionosphere twice. Dr. 3639: 3253: 2915: 2842: 2720: 1934: 1907: 1884: 1876: 1611:

The project involves more than 11 countries and multiple radars in both hemispheres.

1227: 1219: 1167: 1142: 465: 275: 203: 113: 2774: 496: 3593: 3470: 3460: 2467: 1809: 1805: 1532: 1149: 755: 557: 553: 541: 441: 368: 360: 256:

inadvertently provided evidence of the first radio modification of the ionosphere;

177: 93: 30: 3296: 2363:"On the elevation of the electrically conducting strata of the earth's atmosphere" 456:. There is also a seasonal dependence in ionization degree since the local winter 946:

the summertime loss overwhelms the increase in summertime production, and total F

3520: 3503: 3493: 3455: 3208: 2024: 1619: 1244: 1100: 1027: 849: 788: 585: 524: 453: 414: 390: 364: 356: 341: 271: 125: 2891: 2858: 1564:

passive observations of optical and radio emissions generated in the ionosphere

588:. A common example of the D layer in action is the disappearance of distant AM 520:

Ionospheric sub-layers from night to day indicating their approximate altitudes

3525: 3488: 3465: 3413: 1913: 1781:-indices are a measurement of the behavior of the horizontal component of the 1649: 982:

layer at the equator and crests at about 17 degrees in magnetic latitude. The

627: 576: 545: 418: 398: 359:, extends from the surface to about 10 km (6 mi). Above that is the 302: 298: 169: 97: 81: 2907: 2866: 2827: 2629: 2287: 3498: 3475: 3264:, Collection Grenoble Sciences, Université Joseph Fourier Grenoble I, 2000. 3244: 2804:"Some features of the equatorial anomaly revealed by ionospheric tomography" 2621: 2516: 2409:. No. 24473. The New York Times Company. 25 January 1925. pp. 1, 4 2140: 2065: 1872: 1641: 1207: 1161: 817: 744: 549: 165: 161: 116:. It has practical importance because, among other functions, it influences 101: 2691:

Rose, D.C.; Ziauddin, Syed (June 1962). "The polar cap absorption effect".

2670: 2245: 2220: 2060:(2003) . "ionosphere". In Peter Roach; James Hartmann; Jane Setter (eds.). 1836:) generally produce ionospheres. Planets known to have ionospheres include 17: 2802:

Andreeva, E. S.; Franke, S. J.; Yeh, K. C.; Kunitsyn, V. E. (2000-08-15).

2178:] (in German). Leipzig, (Germany): Weidmanns' Bookshop. pp. 1–57. 1386:{\displaystyle f_{\text{muf}}={\frac {f_{\text{critical}}}{\sin \alpha }}} 3235: 3036: 2819: 2014: 1902: 1897: 1631: 922: 918: 711: 697: 337: 329: 274:

in 1947 for his confirmation in 1927 of the existence of the ionosphere.

2263: 144:

received the first trans-Atlantic radio signal on December 12, 1901, in

3507: 3372: 3288: 2712: 2279: 2176:

Findings from the Observations of the Magnetic Society in the Year 1838

1983: 1857: 1777: 1771: 1421: 1211: 1203: 973: 732: 461: 433: 3333: 3308: 2933:. Advisory Group for Aerospace Research and Development. pp. 1–6. 2458: 2433: 2311:". International Conference on 100 Years of Radio, 5–7 September 1995. 2171:

Resultate aus den Beobachtungen des Magnetischen Vereins im Jahre 1838

2975:"Ionospheric Correction Algorithm for Galileo Single Frequency Users" 1963: 1849: 1712:

of refractivity at that tangent point on earth can be reconstructed.

1574: 828:, Millstone Hill, Malvern, St Santin), the ISIS and Alouette topside 751: 619: 410: 294: 153: 149: 3368:

Amsat-Italia project on Ionospheric propagation (ESA SWENET website)

3588: 2931:

High Frequency Radio Communications with Emphasis on Polar Problems

2035:

TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)

1952: 1861: 1546: 958: 909: 736: 523: 515: 495: 457: 394: 257: 121: 88:, from about 48 km (30 mi) to 965 km (600 mi) 29: 2190:

Gauss, Carl Friedrich; Sabine, Elizabeth Juliana, trans. (1841).

301:

was launched to study the ionosphere. Following its success were

199:

discovered some of the ionosphere's radio-electrical properties.

2198:. London, England: Richard and John E. Taylor. pp. 184–251. 1841: 1753: 1700: 1425: 987: 986:

lines are horizontal at the magnetic equator. Solar heating and

762: 333: 3417: 3403: 3378:

NZ4O 160 Meter (Medium Frequency)Radio Propagation Theory Notes

2546: 1672:

radars can also measure neutral atmosphere movements, such as

1489: 1442: 1021: 926: 843: 449: 372: 345: 72: 3283:, Springer-Verlag Berlin Heidelberg, pp. 189–220, 2007. 2646:

Atmospheric and Space Sciences: Neutral Atmospheres: Volume 1

1255:. Since the ionosphere is a plasma, it can be shown that the 444:

that increase ionization on the sunlit side of the Earth and

375:. The number of these free electrons is sufficient to affect 816:(URSI). The major data sources are the worldwide network of 727:) often forms in the electron density profile. Because the F 723:) at night, but during the day, a secondary peak (labelled F 3262:

Du Soleil à la Terre, Aéronomie et météorologie de l'espace

1801: 1488:

is currently used to compensate for ionospheric effects in

978:

It is the occurrence of a trough in the ionization in the F

731:

layer remains by day and night, it is responsible for most

60: 48: 3383: 3152:

The Earth's Ionosphere: Plasma Physics and Electrodynamics

2600:

Chapman, Sydney (1950). "Upper atmospheric nomenclature".

2517:"Firsts in the Space Race. From an Australian perspective" 54: 2547:"Elizabeth A. Essex-Cohen Ionospheric Physics Papers etc" 2351:

be the sea on one side and the upper layer on the other."

136:

As early as 1839, the German mathematician and physicist

3408: 2476:

Ratcliffe, J.A. (1975). "Robert Alexander Watson-Watt".

1585:, Advanced Modular Incoherent Scatter Radar (AMISR) and 1516:

model to compute a range delay along the line-of-sight.

1243:

in the wave forces the electrons in the ionosphere into

804:

observations. One of the most widely used models is the

474:

proposed that the region below the ionosphere be called

260:

ran a series of experiments in 2017 using the eponymous

3373:

NZ4O Solar Space Weather & Geomagnetic Data Archive

3055:

Department of Physics and Astronomy. Uppsala University

1640:

of the ionospheric layers and which are measured by an

1622:, was originally intended to study Earth's ionosphere. 1459: 1318:{\displaystyle f_{\text{critical}}=9\times {\sqrt {N}}} 1114:

Solar particle event § Polar cap absorption events

3075:"Mars Express: First global map of martian ionosphere" 1531:, which uses the ionosphere, is being researched. The 367:. At heights of above 80 km (50 mi), in the 3541: 3389:

Encyclopædia Britannica, Ionosphere and magnetosphere

3309:"Ionospheres: Physics, Plasma Physics, and Chemistry" 1567:

bouncing radio waves of different frequencies from it

1402: 1344: 1288: 69: 66: 63: 57: 3143:

The Upper Atmosphere and Solar-Terrestrial Relations

2892:"Receiver Designs for Low-Latency HF Communications" 2478:

Biographical Memoirs of Fellows of the Royal Society

575:

Medium frequency (MF) and lower high frequency (HF)

432:. The more magnetically active the Sun is, the more 1828:

Ionospheres of other planets and natural satellites

1202:Due to the ability of ionized atmospheric gases to 650:(1850–1925). In 1924 its existence was detected by 51: 3295: 1715:Major GNSS radio occultation missions include the 1408: 1385: 1317: 1275:. If the transmitted frequency is higher than the 2348:. Vol. 33 (10th ed.). pp. 213–235. 963:Electric currents created in sunward ionosphere. 792:and, since several species of ions are present, 2577:"The Ionosphere | Center for Science Education" 245: 3025:Journal of Geophysical Research: Space Physics 2005:High Frequency Active Auroral Research Program 1605:High Frequency Active Auroral Research Program 1239:When a radio wave reaches the ionosphere, the 379:. This portion of the atmosphere is partially 3429: 3281:Handbook of the Solar-Terrestrial Environment 1676:, after making assumptions about ion-neutral 1089:X-rays: sudden ionospheric disturbances (SID) 34:Relationship of the atmosphere and ionosphere 8: 2896:IEEE Transactions on Wireless Communications 2208:: CS1 maint: multiple names: authors list ( 1594:Super Dual Auroral Radar Network (SuperDARN) 1494:US Air Force Geophysical Research Laboratory 2219:Glassmeier, K.-H; Tsurutani, B. T. (2014). 1056:. Unsourced material may be challenged and 878:. Unsourced material may be challenged and 840:Persistent anomalies to the idealized model 3436: 3422: 3414: 252:In the early 1930s, test transmissions of 3332: 3243: 3209:"International Reference Ionosphere 2000" 2890:Arikan, Toros; Singer, Andrew C. (2021). 2874: 2740:. Exeter Books (A Bison Book), New York. 2457: 2244: 2192:"General theory of terrestrial magnetism" 1603:A variety of experiments, such as HAARP ( 1401: 1364: 1358: 1349: 1343: 1308: 1293: 1287: 1076:Learn how and when to remove this message 967:Within approximately ± 20 degrees of the 898:Learn how and when to remove this message 3409:European Incoherent Scatter radar system 2671:"Neutrosphere - Glossary of Meteorology" 1930:Magnetospheric electric convection field 1756:spacecraft that measures the background 1420:, the angle of the wave relative to the 701: 387:which is referred to as the ionosphere. 27:Ionized part of Earth's upper atmosphere 3548: 2049: 1636:Ionograms show the virtual heights and 3171:Radio Amateurs Guide to the Ionosphere 2557:from the original on 11 September 2017 2527:from the original on 11 September 2017 2401:"Sun Affects Radio, Observations Show" 2323:IEEE Antennas and Propagation Magazine 2201: 1551:Properties of Earth's Upper Atmosphere 1328:where N = electron density per m and f 800:depends uniquely on electron density. 646:(1861–1939) and the British physicist 237:in a letter published only in 1969 in 2987:from the original on 10 February 2018 2797: 2795: 1152:will be observable in the night sky. 785:may be described by four parameters: 560:can generate hard X-rays (wavelength 7: 2945:"ION Fellow - Mr. John A. Klobuchar" 2775:"International Reference Ionosphere" 2432:Gardiner, G. W. (13 December 1969). 2321:"Marconi and the History of Radio". 2264:"Wireless telegraphic communication" 1592:coherent scatter radars such as the 1054:adding citations to reliable sources 876:adding citations to reliable sources 814:International Union of Radio Science 452:(time of day) cycle and the 11-year 3307:Schunk, R. W.; Nagy, A. F. (2009). 3192:. Dordrecht: Kluwer Academic Publ. 2955:from the original on 4 October 2017 2262:Marconi, Guglielmo (January 2002). 1108:Protons: polar cap absorption (PCA) 1018:Ephemeral ionospheric perturbations 787:electron density, electron and ion 3190:Wave Propagation in the Ionosphere 3099:NASA/JPL: Titan's upper atmosphere 3007:"Ionospheric Corrections for GNSS" 2673:. Glossary.ametsoc.org. 2012-01-26 2225:History of Geo- and Space Sciences 2137:Wave Propagation in the Ionosphere 1920:International Reference Ionosphere 1492:. This model was developed at the 806:International Reference Ionosphere 769:satellites to study the F region. 758:is called the topside ionosphere. 25: 2737:The Encyclopedia of US Spacecraft 2367:The Electrical World and Engineer 2030:Sura Ionospheric Heating Facility 750:Above the F layer, the number of 638:This region is also known as the 3623: 3611: 3599: 3587: 3575: 3563: 3551: 3404:Super Dual Auroral Radar Network 3394:Current Space Weather Conditions 3154:(2nd ed.). Academic Press. 2505:from the original on 2017-02-20. 2361:Kennelly, A.E. (15 March 1902). 1446: 1026: 914:Overview of ionosphere phenomena 848: 128:that travel through this layer. 112:and forms the inner edge of the 108:. It plays an important role in 44: 3081:from the original on 2015-09-10 2781:from the original on 2011-02-23 2602:Journal of Geophysical Research 2434:"Origin of the term Ionosphere" 1795:Boulder Geomagnetic Observatory 1439:GPS/GNSS ionospheric correction 1099:When the Sun is active, strong 544:-alpha hydrogen radiation at a 104:. The ionosphere is ionized by 3358:Gehred, Paul, and Norm Cohen, 2099:Merriam-Webster.com Dictionary 2062:English Pronouncing Dictionary 1095:Sudden ionospheric disturbance 191:proposed the existence of the 1: 3145:. Cambridge University Press. 2643:Yiğit, Erdal (27 July 2015). 328:The ionosphere is a shell of 217:In 1925, observations during 92:, a region that includes the 3260:J. Lilensten, P.-L. Blelly: 2808:Geophysical Research Letters 2194:. In Taylor, Richard (ed.). 2115:"Earth's Atmospheric Layers" 2113:Zell, Holly (2 March 2015). 2000:Canadian Geospace Monitoring 582:absorption of HF radio waves 580:This is the main reason for 229:In 1926, Scottish physicist 3656:Radio frequency propagation 3298:Atmospheric Electrodynamics 3279:, in: Y. Kamide, A. Chian, 2025:Upper-atmospheric lightning 1504:navigation system uses the 810:Committee on Space Research 715:production is dominated by 160:to produce a signal with a 3672: 3319:(46) (2nd ed.): 556. 3302:. Berlin: Springer Verlag. 3275:P.-L. Blelly, D. Alcaydé: 3141:Hargreaves, J. K. (1992). 2859:10.1038/s41598-021-94326-x 2430:The letter was quoted in: 2340:Heaviside, Oliver (1902). 2070:Cambridge University Press 1959:Earth–ionosphere waveguide 1793:-index is measured at the 1629: 1477: 1231:where milliseconds count. 1159: 1130: 1111: 1092: 695: 606: 164:of approximately 500 3516: 3484: 3451: 3384:USGS Geomagnetism Program 3169:McNamara, Leo F. (1994). 1979:Line-of-sight propagation 1974:Ionospheric scintillation 1925:Ionospheric dynamo region 1731:Indices of the ionosphere 1682:ionospheric dynamo region 1656:Incoherent scatter radars 1537:electromagnetic induction 1008:ionospheric dynamo region 592:stations in the daytime. 332:and electrically charged 3399:Current Solar X-Ray Flux 3361:SWPC's Radio User's Page 3207:Bilitza, Dieter (2001). 3122:Davies, Kenneth (1990). 2980:. Galileo Open Service. 2908:10.1109/TWC.2020.3046475 2346:Encyclopaedia Britannica 1945:Van Allen radiation belt 1764:Geomagnetic disturbances 747:) radio communications. 739:waves and long distance 640:Kennelly–Heaviside layer 609:Kennelly–Heaviside layer 446:solar energetic particle 193:Kennelly–Heaviside layer 146:St. John's, Newfoundland 3051:"Planetary ionospheres" 2622:10.1029/JZ055i004p00395 1409:{\displaystyle \alpha } 1235:Mechanism of refraction 1206:high frequency (HF, or 941:At mid-latitudes, the F 683:makes VHF-operating by 351:The lowest part of the 223:Dr. Alfred N. Goldsmith 212:amateur radio operators 110:atmospheric electricity 3150:Kelley, M. C. (2009). 2777:. Ccmc.gsfc.nasa.gov. 2499:"Gakona HAARPoon 2017" 2246:10.5194/hgss-5-11-2014 1969:Ionospheric absorption 1688:GNSS radio occultation 1552: 1480:Total electron content 1410: 1387: 1319: 1172:electron precipitation 1121:Coronal mass ejections 984:Earth's magnetic field 964: 915: 834:total electron content 707: 681:Sporadic E propagation 532: 521: 501: 314:total electron content 250: 182:Glace Bay, Nova Scotia 35: 2693:Space Science Reviews 2217:English translation: 2188:English translation: 1577:, Sondre Stromfjord, 1550: 1529:electrodynamic tether 1498:John (Jack) Klobuchar 1411: 1388: 1320: 1160:Further information: 1112:Further information: 1012:equatorial electrojet 1002:Equatorial electrojet 962: 913: 705: 644:Arthur Edwin Kennelly 527: 519: 499: 318:Elizabeth Essex-Cohen 197:Arthur Edwin Kennelly 158:spark-gap transmitter 120:to distant places on 33: 3294:Volland, H. (1984). 3236:10.1029/2000RS002432 3037:10.1029/2022JA030861 2820:10.1029/1999GL003725 2734:Yenne, Bill (1985). 1638:critical frequencies 1400: 1342: 1286: 1050:improve this section 872:improve this section 492:Layers of ionization 305:in 1965 and the two 233:introduced the term 138:Carl Friedrich Gauss 132:History of discovery 3651:Terrestrial plasmas 3325:2001EOSTr..82..556K 3228:2001RaSc...36..261B 3108:Accessed 2010-08-25 2929:Lied, Finn (1967). 2705:1962SSRv....1..115R 2614:1950JGR....55..395C 2450:1969Natur.224.1096G 2237:2014HGSS....5...11G 2020:Soft gamma repeater 1940:Schumann resonances 1869:atmosphere of Titan 1819:-index, called the 1678:collision frequency 1646:William Roy Piggott 1573:radars such as the 1262:Dispersion (optics) 1226:frequencies, as do 1198:Radio communication 996:equatorial fountain 824:radars (Jicamarca, 717:extreme ultraviolet 597:solar proton events 556:(NO). In addition, 500:Ionospheric layers. 344:radiation from the 156:, Cornwall, used a 86:atmosphere of Earth 3445:Earth's atmosphere 3289:10.1007/11367758_8 3188:Rawer, K. (1993). 3104:2011-05-11 at the 2847:Scientific Reports 2713:10.1007/BF00174638 2406:The New York Times 2307:2009-01-23 at the 2300:John S. Belrose, " 2280:10.1007/bf02836176 2135:Rawer, K. (1993). 2102:. Merriam-Webster. 2010:Ionospheric heater 1834:natural satellites 1699:technique where a 1670:Incoherent scatter 1661:Incoherent scatter 1571:incoherent scatter 1553: 1520:Other applications 1458:. You can help by 1406: 1383: 1315: 1269:critical frequency 965: 955:Equatorial anomaly 916: 822:incoherent scatter 761:From 1972 to 1975 708: 652:Edward V. Appleton 533: 522: 502: 483:neutral atmosphere 353:Earth's atmosphere 268:Edward V. Appleton 231:Robert Watson-Watt 184:, one year later. 124:. It also affects 84:part of the upper 36: 3539: 3538: 3334:10.1029/01EO00328 3270:978-2-86883-467-6 3199:978-0-7923-0775-4 3180:978-0-89464-804-5 3133:978-0-86341-186-1 3124:Ionospheric Radio 2814:(16): 2465–2468. 2747:978-0-671-07580-4 2459:10.1038/2241096a0 2079:978-3-12-539683-8 1821:planetary A-index 1783:geomagnetic field 1693:Radio occultation 1674:atmospheric tides 1616:Arecibo Telescope 1476: 1475: 1424:, and sin is the 1381: 1367: 1352: 1313: 1296: 1137:Ionospheric storm 1133:Geomagnetic storm 1086: 1085: 1078: 908: 907: 900: 812:(COSPAR) and the 798:Radio propagation 794:ionic composition 779:ionospheric model 773:Ionospheric model 767:AEROS and AEROS B 529:Lightning sprites 377:radio propagation 280:Maurice V. Wilkes 262:Luxembourg Effect 208:Radio Act of 1912 142:Guglielmo Marconi 118:radio propagation 96:and parts of the 16:(Redirected from 3663: 3628: 3627: 3626: 3616: 3615: 3614: 3604: 3603: 3602: 3592: 3591: 3580: 3579: 3578: 3568: 3567: 3556: 3555: 3554: 3547: 3438: 3431: 3424: 3415: 3348: 3336: 3313:Eos Transactions 3303: 3301: 3257: 3247: 3245:2060/19910021307 3213: 3203: 3184: 3165: 3146: 3137: 3109: 3096: 3090: 3089: 3087: 3086: 3071: 3065: 3064: 3062: 3061: 3047: 3041: 3040: 3020: 3014: 3013: 3011: 3003: 2997: 2996: 2994: 2992: 2986: 2979: 2971: 2965: 2964: 2962: 2960: 2941: 2935: 2934: 2926: 2920: 2919: 2902:(5): 3005–3015. 2887: 2881: 2880: 2878: 2838: 2832: 2831: 2799: 2790: 2789: 2787: 2786: 2771: 2765: 2762: 2756: 2751: 2731: 2725: 2724: 2688: 2682: 2681: 2679: 2678: 2667: 2661: 2660: 2640: 2634: 2633: 2597: 2591: 2590: 2588: 2587: 2573: 2567: 2566: 2564: 2562: 2543: 2537: 2536: 2534: 2532: 2513: 2507: 2506: 2495: 2489: 2485: 2471: 2461: 2425: 2419: 2418: 2416: 2414: 2397: 2391: 2381: 2375: 2374: 2358: 2352: 2349: 2337: 2331: 2330: 2318: 2312: 2298: 2292: 2291: 2259: 2253: 2250: 2248: 2213: 2207: 2199: 2179: 2165: 2159: 2158: 2132: 2126: 2125: 2123: 2122: 2110: 2104: 2103: 2090: 2084: 2083: 2054: 1706:Abel's transform 1471: 1468: 1450: 1443: 1433:cutoff frequency 1418:angle of arrival 1415: 1413: 1412: 1407: 1392: 1390: 1389: 1384: 1382: 1380: 1369: 1368: 1365: 1359: 1354: 1353: 1350: 1324: 1322: 1321: 1316: 1314: 1309: 1298: 1297: 1294: 1277:plasma frequency 1257:refractive index 1253:geometric optics 1174:" (LEP) events. 1145:and ionosphere. 1081: 1074: 1070: 1067: 1061: 1030: 1022: 969:magnetic equator 903: 896: 892: 889: 883: 852: 844: 648:Oliver Heaviside 563: 254:Radio Luxembourg 189:Oliver Heaviside 79: 78: 75: 74: 71: 68: 65: 62: 59: 56: 53: 50: 21: 3671: 3670: 3666: 3665: 3664: 3662: 3661: 3660: 3636: 3635: 3634: 3624: 3622: 3612: 3610: 3600: 3598: 3586: 3576: 3574: 3562: 3552: 3550: 3542: 3540: 3535: 3512: 3480: 3447: 3442: 3355: 3345: 3306: 3293: 3211: 3206: 3200: 3187: 3181: 3168: 3162: 3149: 3140: 3134: 3121: 3118: 3113: 3112: 3106:Wayback Machine 3097: 3093: 3084: 3082: 3073: 3072: 3068: 3059: 3057: 3049: 3048: 3044: 3022: 3021: 3017: 3009: 3005: 3004: 3000: 2990: 2988: 2984: 2977: 2973: 2972: 2968: 2958: 2956: 2943: 2942: 2938: 2928: 2927: 2923: 2889: 2888: 2884: 2840: 2839: 2835: 2801: 2800: 2793: 2784: 2782: 2773: 2772: 2768: 2763: 2759: 2748: 2733: 2732: 2728: 2690: 2689: 2685: 2676: 2674: 2669: 2668: 2664: 2657: 2642: 2641: 2637: 2599: 2598: 2594: 2585: 2583: 2575: 2574: 2570: 2560: 2558: 2551:harveycohen.net 2545: 2544: 2540: 2530: 2528: 2521:harveycohen.net 2515: 2514: 2510: 2497: 2496: 2492: 2475: 2431: 2426: 2422: 2412: 2410: 2399: 2398: 2394: 2382: 2378: 2360: 2359: 2355: 2339: 2338: 2334: 2320: 2319: 2315: 2309:Wayback Machine 2299: 2295: 2261: 2260: 2256: 2218: 2200: 2189: 2167: 2166: 2162: 2155: 2145:Kluwer Academic 2134: 2133: 2129: 2120: 2118: 2112: 2111: 2107: 2092: 2091: 2087: 2080: 2056: 2055: 2051: 2046: 2041: 1990: 1893: 1830: 1818: 1766: 1746:radio telescope 1741: 1739:Solar intensity 1733: 1690: 1658: 1634: 1628: 1558: 1545: 1522: 1486:Klobuchar model 1482: 1472: 1466: 1463: 1456:needs expansion 1441: 1398: 1397: 1370: 1360: 1345: 1340: 1339: 1331: 1289: 1284: 1283: 1237: 1224:shortwave radio 1200: 1195: 1188: 1184: 1164: 1158: 1139: 1131:Main articles: 1129: 1116: 1110: 1097: 1091: 1082: 1071: 1065: 1062: 1047: 1031: 1020: 1004: 981: 957: 949: 944: 939: 904: 893: 887: 884: 869: 853: 842: 820:, the powerful 775: 735:propagation of 730: 726: 722: 700: 694: 673: 668: 665: 633: 625: 611: 605: 571: 567: 564:) that ionize N 561: 538: 512: 508: 494: 438:coronal heating 403:solar radiation 383:and contains a 326: 288:Vitaly Ginzburg 284:J. A. Ratcliffe 221:in New York by 219:a solar eclipse 172:for the letter 134: 106:solar radiation 90:above sea level 47: 43: 28: 23: 22: 15: 12: 11: 5: 3669: 3667: 3659: 3658: 3653: 3648: 3638: 3637: 3633: 3632: 3620: 3608: 3596: 3584: 3572: 3560: 3558:Earth sciences 3537: 3536: 3534: 3533: 3528: 3523: 3517: 3514: 3513: 3511: 3510: 3501: 3496: 3491: 3485: 3482: 3481: 3479: 3478: 3473: 3468: 3463: 3458: 3452: 3449: 3448: 3443: 3441: 3440: 3433: 3426: 3418: 3412: 3411: 3406: 3401: 3396: 3391: 3386: 3381: 3375: 3370: 3365: 3354: 3353:External links 3351: 3350: 3349: 3343: 3304: 3291: 3273: 3258: 3222:(2): 261–275. 3204: 3198: 3185: 3179: 3166: 3160: 3147: 3138: 3132: 3117: 3114: 3111: 3110: 3091: 3066: 3042: 3015: 2998: 2966: 2936: 2921: 2882: 2833: 2791: 2766: 2757: 2746: 2726: 2683: 2662: 2655: 2635: 2608:(4): 395–399. 2592: 2581:scied.ucar.edu 2568: 2538: 2508: 2501:. 2017-02-19. 2490: 2488: 2487: 2472: 2444:(5224): 1096. 2420: 2392: 2376: 2353: 2332: 2313: 2293: 2254: 2252: 2251: 2215: 2160: 2153: 2127: 2105: 2085: 2078: 2048: 2047: 2045: 2042: 2040: 2039: 2038: 2037: 2032: 2027: 2022: 2017: 2012: 2007: 2002: 1991: 1989: 1988: 1987: 1986: 1981: 1976: 1971: 1966: 1961: 1949: 1948: 1947: 1942: 1937: 1932: 1927: 1922: 1910: 1905: 1900: 1894: 1892: 1889: 1829: 1826: 1825: 1824: 1816: 1808:(or in non-SI 1798: 1765: 1762: 1740: 1737: 1732: 1729: 1710:radial profile 1697:remote sensing 1689: 1686: 1657: 1654: 1630:Main article: 1627: 1624: 1601: 1600: 1597: 1590: 1579:Millstone Hill 1568: 1565: 1557: 1554: 1544: 1541: 1521: 1518: 1496:circa 1974 by 1474: 1473: 1453: 1451: 1440: 1437: 1405: 1394: 1393: 1379: 1376: 1373: 1363: 1357: 1348: 1329: 1326: 1325: 1312: 1307: 1304: 1301: 1292: 1241:electric field 1236: 1233: 1199: 1196: 1194: 1191: 1186: 1182: 1157: 1154: 1128: 1125: 1109: 1106: 1093:Main article: 1090: 1087: 1084: 1083: 1034: 1032: 1025: 1019: 1016: 1003: 1000: 979: 956: 953: 947: 942: 938: 937:Winter anomaly 935: 906: 905: 856: 854: 847: 841: 838: 774: 771: 741:high frequency 728: 724: 720: 696:Main article: 693: 690: 685:radio amateurs 671: 667: 663: 660: 631: 623: 607:Main article: 604: 601: 590:broadcast band 569: 565: 552:(nm) ionizing 537: 534: 510: 506: 493: 490: 472:Sydney Chapman 430:solar activity 325: 322: 270:was awarded a 133: 130: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 3668: 3657: 3654: 3652: 3649: 3647: 3644: 3643: 3641: 3631: 3621: 3619: 3609: 3607: 3597: 3595: 3590: 3585: 3583: 3573: 3571: 3566: 3561: 3559: 3549: 3545: 3532: 3529: 3527: 3524: 3522: 3519: 3518: 3515: 3509: 3505: 3502: 3500: 3497: 3495: 3492: 3490: 3487: 3486: 3483: 3477: 3474: 3472: 3469: 3467: 3464: 3462: 3459: 3457: 3454: 3453: 3450: 3446: 3439: 3434: 3432: 3427: 3425: 3420: 3419: 3416: 3410: 3407: 3405: 3402: 3400: 3397: 3395: 3392: 3390: 3387: 3385: 3382: 3379: 3376: 3374: 3371: 3369: 3366: 3363: 3362: 3357: 3356: 3352: 3346: 3344:9780521877060 3340: 3335: 3330: 3326: 3322: 3318: 3314: 3310: 3305: 3300: 3299: 3292: 3290: 3286: 3282: 3278: 3274: 3271: 3267: 3263: 3259: 3255: 3251: 3246: 3241: 3237: 3233: 3229: 3225: 3221: 3217: 3216:Radio Science 3210: 3205: 3201: 3195: 3191: 3186: 3182: 3176: 3172: 3167: 3163: 3161:9780120884254 3157: 3153: 3148: 3144: 3139: 3135: 3129: 3125: 3120: 3119: 3115: 3107: 3103: 3100: 3095: 3092: 3080: 3076: 3070: 3067: 3056: 3052: 3046: 3043: 3038: 3034: 3030: 3026: 3019: 3016: 3008: 3002: 2999: 2983: 2976: 2970: 2967: 2954: 2950: 2946: 2940: 2937: 2932: 2925: 2922: 2917: 2913: 2909: 2905: 2901: 2897: 2893: 2886: 2883: 2877: 2872: 2868: 2864: 2860: 2856: 2852: 2848: 2844: 2837: 2834: 2829: 2825: 2821: 2817: 2813: 2809: 2805: 2798: 2796: 2792: 2780: 2776: 2770: 2767: 2764:Bilitza, 2001 2761: 2758: 2755: 2749: 2743: 2739: 2736: 2730: 2727: 2722: 2718: 2714: 2710: 2706: 2702: 2698: 2694: 2687: 2684: 2672: 2666: 2663: 2658: 2656:9783319215815 2652: 2648: 2647: 2639: 2636: 2631: 2627: 2623: 2619: 2615: 2611: 2607: 2603: 2596: 2593: 2582: 2578: 2572: 2569: 2556: 2552: 2548: 2542: 2539: 2526: 2522: 2518: 2512: 2509: 2504: 2500: 2494: 2491: 2483: 2479: 2473: 2469: 2465: 2460: 2455: 2451: 2447: 2443: 2439: 2435: 2429: 2428: 2424: 2421: 2408: 2407: 2402: 2396: 2393: 2390: 2385: 2380: 2377: 2372: 2368: 2364: 2357: 2354: 2347: 2343: 2336: 2333: 2328: 2324: 2317: 2314: 2310: 2306: 2303: 2297: 2294: 2289: 2285: 2281: 2277: 2274:(1): 95–101. 2273: 2269: 2265: 2258: 2255: 2247: 2242: 2238: 2234: 2230: 2226: 2222: 2216: 2211: 2205: 2197: 2193: 2187: 2186: 2184: 2177: 2173: 2172: 2164: 2161: 2156: 2154:0-7923-0775-5 2150: 2146: 2142: 2138: 2131: 2128: 2116: 2109: 2106: 2101: 2100: 2095: 2089: 2086: 2081: 2075: 2071: 2067: 2063: 2059: 2058:Jones, Daniel 2053: 2050: 2043: 2036: 2033: 2031: 2028: 2026: 2023: 2021: 2018: 2016: 2013: 2011: 2008: 2006: 2003: 2001: 1998: 1997: 1996: 1993: 1992: 1985: 1982: 1980: 1977: 1975: 1972: 1970: 1967: 1965: 1962: 1960: 1957: 1956: 1955: 1954: 1950: 1946: 1943: 1941: 1938: 1936: 1935:Protonosphere 1933: 1931: 1928: 1926: 1923: 1921: 1918: 1917: 1916: 1915: 1911: 1909: 1908:Space physics 1906: 1904: 1901: 1899: 1896: 1895: 1890: 1888: 1886: 1882: 1878: 1874: 1870: 1865: 1863: 1859: 1855: 1851: 1847: 1843: 1839: 1835: 1827: 1822: 1815: 1811: 1807: 1804:units called 1803: 1799: 1796: 1792: 1788: 1784: 1780: 1779: 1774: 1773: 1768: 1767: 1763: 1761: 1759: 1755: 1749: 1747: 1738: 1736: 1730: 1728: 1726: 1722: 1718: 1713: 1711: 1707: 1702: 1698: 1694: 1687: 1685: 1683: 1679: 1675: 1671: 1667: 1662: 1655: 1653: 1651: 1647: 1643: 1639: 1633: 1625: 1623: 1621: 1617: 1612: 1608: 1606: 1598: 1595: 1591: 1588: 1584: 1580: 1576: 1572: 1569: 1566: 1563: 1562: 1561: 1555: 1549: 1542: 1540: 1538: 1534: 1530: 1527: 1519: 1517: 1515: 1511: 1507: 1506:NeQuick model 1503: 1499: 1495: 1491: 1487: 1481: 1470: 1461: 1457: 1454:This section 1452: 1449: 1445: 1444: 1438: 1436: 1434: 1429: 1427: 1423: 1419: 1403: 1377: 1374: 1371: 1361: 1355: 1346: 1338: 1337: 1336: 1333: 1310: 1305: 1302: 1299: 1290: 1282: 1281: 1280: 1278: 1274: 1270: 1265: 1263: 1258: 1254: 1249: 1246: 1242: 1234: 1232: 1229: 1228:radio amateur 1225: 1221: 1220:sunspot cycle 1217: 1213: 1209: 1205: 1197: 1192: 1190: 1178: 1175: 1173: 1169: 1168:magnetosphere 1163: 1155: 1153: 1151: 1146: 1144: 1143:magnetosphere 1138: 1134: 1126: 1124: 1122: 1115: 1107: 1105: 1102: 1096: 1088: 1080: 1077: 1069: 1059: 1055: 1051: 1045: 1044: 1040: 1035:This section 1033: 1029: 1024: 1023: 1017: 1015: 1013: 1009: 1001: 999: 997: 993: 989: 985: 977: 975: 970: 961: 954: 952: 936: 934: 932: 928: 924: 920: 912: 902: 899: 891: 881: 877: 873: 867: 866: 862: 857:This section 855: 851: 846: 845: 839: 837: 835: 831: 827: 823: 819: 815: 811: 807: 801: 799: 795: 791: 790: 784: 780: 772: 770: 768: 765:launched the 764: 759: 757: 753: 748: 746: 742: 738: 734: 718: 713: 704: 699: 691: 689: 686: 682: 677: 661: 659: 657: 656:Miles Barnett 653: 649: 645: 641: 636: 630:events, the E 629: 621: 616: 610: 602: 600: 598: 593: 591: 587: 583: 578: 573: 559: 555: 551: 547: 543: 535: 530: 526: 518: 514: 498: 491: 489: 487: 485: 484: 479: 478: 473: 469: 467: 466:mid-latitudes 463: 459: 455: 451: 447: 443: 439: 435: 431: 426: 424: 423:recombination 420: 416: 412: 408: 404: 400: 396: 392: 388: 386: 382: 378: 374: 370: 366: 362: 358: 354: 349: 347: 343: 339: 335: 331: 323: 321: 319: 315: 310: 308: 304: 300: 296: 293:In 1962, the 291: 289: 285: 281: 277: 276:Lloyd Berkner 273: 269: 265: 263: 259: 255: 249: 244: 242: 241: 236: 232: 227: 224: 220: 215: 213: 209: 205: 204:U.S. Congress 202:In 1912, the 200: 198: 194: 190: 185: 183: 179: 175: 171: 167: 163: 159: 155: 151: 147: 143: 139: 131: 129: 127: 123: 119: 115: 114:magnetosphere 111: 107: 103: 99: 95: 91: 87: 83: 77: 41: 32: 19: 3630:Solar System 3530: 3471:Thermosphere 3461:Stratosphere 3359: 3316: 3312: 3297: 3280: 3276: 3261: 3219: 3215: 3189: 3170: 3151: 3142: 3123: 3094: 3083:. Retrieved 3069: 3058:. Retrieved 3054: 3045: 3028: 3024: 3018: 3001: 2989:. Retrieved 2969: 2957:. Retrieved 2948: 2939: 2930: 2924: 2899: 2895: 2885: 2853:(1): 14695. 2850: 2846: 2836: 2811: 2807: 2783:. Retrieved 2769: 2760: 2753: 2738: 2735: 2729: 2696: 2692: 2686: 2675:. Retrieved 2665: 2649:. Springer. 2645: 2638: 2605: 2601: 2595: 2584:. Retrieved 2580: 2571: 2559:. Retrieved 2550: 2541: 2529:. Retrieved 2520: 2511: 2493: 2481: 2477: 2441: 2437: 2423: 2411:. Retrieved 2404: 2395: 2379: 2370: 2366: 2356: 2345: 2342:"Telegraphy" 2335: 2326: 2322: 2316: 2296: 2271: 2267: 2257: 2231:(1): 11–62. 2228: 2224: 2195: 2182: 2175: 2170: 2163: 2136: 2130: 2119:. Retrieved 2108: 2097: 2094:"ionosphere" 2088: 2061: 2052: 1994: 1951: 1912: 1866: 1831: 1820: 1813: 1790: 1786: 1782: 1776: 1770: 1757: 1750: 1742: 1734: 1714: 1691: 1659: 1637: 1635: 1613: 1609: 1602: 1559: 1543:Measurements 1533:space tether 1523: 1513: 1509: 1505: 1497: 1493: 1485: 1483: 1467:October 2013 1464: 1460:adding to it 1455: 1430: 1395: 1334: 1327: 1266: 1250: 1238: 1201: 1193:Applications 1179: 1176: 1165: 1147: 1140: 1117: 1101:solar flares 1098: 1072: 1063: 1048:Please help 1036: 1005: 995: 972: 968: 966: 940: 917: 894: 885: 870:Please help 858: 802: 793: 786: 778: 776: 760: 756:plasmasphere 749: 709: 669: 637: 612: 594: 574: 558:solar flares 554:nitric oxide 542:Lyman series 539: 509:layer. The F 503: 488: 482: 481: 477:neutrosphere 476: 475: 470: 442:solar flares 427: 406: 397:and shorter 389: 380: 369:thermosphere 361:stratosphere 350: 327: 311: 292: 266: 251: 248:this series. 246: 238: 234: 228: 216: 206:imposed the 201: 186: 178:Jack Belrose 173: 135: 94:thermosphere 39: 37: 3618:Outer space 3606:Spaceflight 3521:Ozone layer 3504:Thermopause 3494:Stratopause 3456:Troposphere 2949:www.ion.org 2486:See p. 554. 2474:See also: 2214:See p. 229. 1680:across the 1620:Puerto Rico 1618:located in 1526:open system 1245:oscillation 789:temperature 586:cosmic rays 577:radio waves 454:solar cycle 415:temperature 399:wavelengths 391:Ultraviolet 365:ozone layer 357:troposphere 342:ultraviolet 272:Nobel Prize 126:GPS signals 18:Ionospheric 3646:Ionosphere 3640:Categories 3531:Ionosphere 3526:Turbopause 3489:Tropopause 3466:Mesosphere 3277:Ionosphere 3116:References 3085:2015-10-31 3060:2023-06-04 2991:9 February 2785:2011-11-08 2699:(1): 115. 2677:2022-08-12 2586:2023-04-05 2484:: 549–568. 2413:25 January 2373:(11): 473. 2121:2020-10-23 1914:Geophysics 1758:X-ray flux 1650:Karl Rawer 1478:See also: 1428:function. 1332:is in Hz. 992:horizontal 974:equatorial 818:ionosondes 628:sporadic E 546:wavelength 458:hemisphere 419:ionization 324:Geophysics 303:Alouette 2 299:Alouette 1 297:satellite 235:ionosphere 170:Morse code 98:mesosphere 40:ionosphere 3582:Astronomy 3499:Mesopause 3476:Exosphere 3254:116976314 2916:233990323 2867:2045-2322 2828:0094-8276 2721:122220113 2630:0148-0227 2288:0971-8044 2268:Resonance 2204:cite book 2141:Dordrecht 2066:Cambridge 1666:coherence 1642:ionosonde 1626:Ionograms 1587:Jicamarca 1404:α 1378:α 1375:⁡ 1306:× 1273:incidence 1208:shortwave 1162:Lightning 1156:Lightning 1066:July 2024 1037:does not 971:, is the 919:Ionograms 888:July 2024 859:does not 745:shortwave 562:< 1 nm 550:nanometre 548:of 121.6 407:ionizing, 338:molecules 330:electrons 187:In 1902, 162:frequency 102:exosphere 80:) is the 3102:Archived 3079:Archived 2982:Archived 2953:Archived 2779:Archived 2555:Archived 2525:Archived 2503:Archived 2305:Archived 2015:S4 Index 1903:Geospace 1898:Aeronomy 1891:See also 1881:Ganymede 1632:Ionogram 1556:Overview 1366:critical 1330:critical 1295:critical 976:anomaly. 923:electron 830:sounders 743:(HF, or 698:F region 676:sporadic 295:Canadian 148:(now in 3570:Weather 3544:Portals 3508:Exobase 3321:Bibcode 3224:Bibcode 2876:8289839 2701:Bibcode 2610:Bibcode 2468:4296253 2446:Bibcode 2233:Bibcode 1995:Related 1984:Sferics 1858:Neptune 1846:Jupiter 1583:Arecibo 1514:NeQuick 1510:GALILEO 1502:Galileo 1500:. The 1422:horizon 1212:skywave 1204:refract 1150:aurorae 1058:removed 1043:sources 880:removed 865:sources 826:Arecibo 733:skywave 712:F layer 692:F layer 674:layer ( 615:E layer 603:E layer 595:During 536:D layer 464:zones, 462:auroral 450:diurnal 434:sunspot 411:photons 381:ionized 82:ionized 3341: 3268: 3252: 3196: 3177: 3158: 3130: 3031:(10). 2914: 2873: 2865: 2826: 2752:p. 12 2744: 2719: 2653: 2628: 2466: 2438:Nature 2389:backup 2286: 2151: 2117:. NASA 2076: 1964:Fading 1885:Triton 1883:, and 1877:Europa 1854:Uranus 1850:Saturn 1823:(PAI). 1806:teslas 1785:. The 1775:- and 1725:COSMIC 1723:, and 1596:radars 1589:radars 1575:EISCAT 1396:where 1127:Storms 931:plasma 783:plasma 752:oxygen 620:oxygen 409:since 393:(UV), 385:plasma 355:, the 240:Nature 154:Poldhu 150:Canada 3594:Stars 3250:S2CID 3212:(PDF) 3010:(PDF) 2985:(PDF) 2978:(PDF) 2959:8 May 2912:S2CID 2754:AEROS 2717:S2CID 2561:8 May 2531:8 May 2464:S2CID 2174:[ 2044:Notes 1953:Radio 1862:Pluto 1838:Venus 1810:gauss 1721:CHAMP 1717:GRACE 1695:is a 988:tidal 737:radio 670:The E 666:layer 568:and O 480:(the 395:X-ray 334:atoms 258:HAARP 122:Earth 3339:ISBN 3266:ISBN 3194:ISBN 3175:ISBN 3156:ISBN 3128:ISBN 2993:2018 2961:2018 2863:ISSN 2824:ISSN 2742:ISBN 2651:ISBN 2626:ISSN 2563:2018 2533:2018 2415:2024 2284:ISSN 2210:link 2149:ISBN 2074:ISBN 1867:The 1860:and 1842:Mars 1769:The 1754:GOES 1708:, a 1701:GNSS 1648:and 1524:The 1431:The 1426:sine 1267:The 1216:hops 1135:and 1041:any 1039:cite 863:any 861:cite 763:NASA 710:The 654:and 613:The 405:are 336:and 307:ISIS 282:and 100:and 38:The 3329:doi 3285:doi 3240:hdl 3232:doi 3033:doi 3029:127 2904:doi 2871:PMC 2855:doi 2816:doi 2709:doi 2618:doi 2454:doi 2442:224 2276:doi 2241:doi 1490:GPS 1462:. 1372:sin 1351:muf 1052:by 927:ion 874:by 777:An 486:). 421:is 401:of 373:ion 346:Sun 210:on 166:kHz 73:ɪər 3642:: 3506:/ 3337:. 3327:. 3317:82 3315:. 3311:. 3248:. 3238:. 3230:. 3220:36 3218:. 3214:. 3173:. 3077:. 3053:. 3027:. 2951:. 2947:. 2910:. 2900:20 2898:. 2894:. 2869:. 2861:. 2851:11 2849:. 2845:. 2822:. 2812:27 2810:. 2806:. 2794:^ 2715:. 2707:. 2695:. 2624:. 2616:. 2606:55 2604:. 2579:. 2553:. 2549:. 2523:. 2519:. 2482:21 2480:. 2462:. 2452:. 2440:. 2436:. 2403:. 2371:39 2369:. 2365:. 2344:. 2327:46 2325:. 2282:. 2270:. 2266:. 2239:. 2227:. 2223:. 2206:}} 2202:{{ 2147:. 2143:: 2139:. 2096:. 2072:. 2068:: 2064:. 1887:. 1879:, 1875:, 1873:Io 1864:. 1856:, 1852:, 1848:, 1844:, 1840:, 1802:SI 1727:. 1719:, 1684:. 1581:, 1539:. 1508:. 1416:= 1264:. 1181:(E 1014:. 998:. 796:. 658:. 622:(O 348:. 264:. 243:: 49:aɪ 3546:: 3437:e 3430:t 3423:v 3364:. 3347:. 3331:: 3323:: 3287:: 3272:. 3256:. 3242:: 3234:: 3226:: 3202:. 3183:. 3164:. 3136:. 3088:. 3063:. 3039:. 3035:: 3012:. 2995:. 2963:. 2918:. 2906:: 2879:. 2857:: 2830:. 2818:: 2788:. 2750:. 2723:. 2711:: 2703:: 2697:1 2680:. 2659:. 2632:. 2620:: 2612:: 2589:. 2565:. 2535:. 2470:. 2456:: 2448:: 2417:. 2329:. 2290:. 2278:: 2272:7 2249:. 2243:: 2235:: 2229:5 2212:) 2157:. 2124:. 2082:. 1817:p 1814:A 1797:. 1791:K 1787:K 1778:K 1772:A 1469:) 1465:( 1362:f 1356:= 1347:f 1311:N 1303:9 1300:= 1291:f 1187:s 1183:s 1079:) 1073:( 1068:) 1064:( 1060:. 1046:. 980:2 948:2 943:2 929:- 925:/ 901:) 895:( 890:) 886:( 882:. 868:. 729:2 725:1 721:2 672:s 664:s 662:E 632:s 624:2 570:2 566:2 531:. 511:2 507:1 505:F 174:S 76:/ 70:f 67:s 64:ˌ 61:ə 58:n 55:ɒ 52:ˈ 46:/ 42:( 20:)

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.