|
|
msu94
Joined: 16 Feb 2002
Posts: 207
Location: Tucson, AZ |
 Sat Mar 27, 2004 3:07 am
|
 |
|
CIA is not in Norfolk.
|
| |
|
|
Msredsonya
Joined: 25 Mar 2004
Posts: 3
Location: FL |
|
Sat Mar 27, 2004 8:17 am
|
|
|
Obviously space physics relies on radars to study the mechanics of space physics but what does the word RADAR actually stand for ? Radio Detection and Ranging. What does it refer to? The use of radio waves to detect objects and determine the distance (range) to the object.
Radars emit radio pulses that are comprised of oscillating electric and magnetic fields but the pulses have different scattering characteristics, depending on whether the electric fields oscillate horizontally or vertically, some can even spiral during propagation.
The radio pulses emitted can be very powerful because they are ampliflied by the transmitter, in some cases as high as 1 MegaWatt, i.e. 1 million watts peak power. Reference, the standard house light bulb draws about 60 watts, and a toaster draws about 1000 watts.
Additionally, not all the pulse transmission is absorbed or reflected back from the object it is targeting. Some continues to go through the object or around it. Especially in scattering targets (rain, insects, birds, the air).
So I can see where Mojo can bring up the point that radars emit radio waves/frequencies/power.
Why would they rely on radars to see the effects of space physics if nothing was going to be seen/happen on the radar?
Why would they have developed radars, Windprofiler radars, that can measure other levels of the atmosphere besides the previously known ionosphere, such as the tropospheric and stratospheric atmosphere if they weren't not going to be able to see the effects manifested on the radar? These radars usually work at frequencies of around 50 MHz.
excerpt taken from website listed below...."Space physics studies the Sun (and its extension, the solar wind) and all planets with plasma environments, including Earth. One of the main tasks in space physics is to explain the Solar wind - magnetosphere - ionosphere - atmosphere coupling that is responsible for many important phenomena." end of excerpt....
Space physics does includes the study of the ionosphere) The ionosphere is special in that it can REFLECT radio waves....(HAARP is a ionosphere heating instrument. There are several ionosphere heaters world wide. I will post a list and what information I have accumulated to date at a later time as I do not have the research I have been doing on worldwide ionosphere heaters at my fingertips. Why have I been doing the research, because obviously if one beaming ionospheric heater can effect the atmosphere than what happens when you add all the OTHER ionospheric heaters into the picture !)
This website, a scientific one, is just one example of a another (HAARP) ionospheric heater in another country. EISCAT is their own special incoherent scatter radar for their study of the effect of their ionospheric heating.
EISCAT's ionospheric Heating facility including Dynasonde
The Heating facility is situated in Ramfjordmoen, near Tromso in northern Norway, next to the EISCAT UHF and VHF incoherent scatter radars. The facility was built by the Max-Planck-Institut fur Aeronomie in collaboration with the University of Tromso in 1979. In January 1993 the facility was transferred to EISCAT, but the institute still is one of its major users.
The facility is used to conduct plasma physics and active geophysical research of the lower and upper ionosphere by the controlled injection of powerful HF (4-8 MHz) waves. A technical description is given below.
Scientists from MPAe who are closely involved in Heating experiments are: T. Hagfors, H. Kohl, M. T. Rietveld, P. Stubbe, as well as guest scientists and collaborators. (M. Rietveld works half his time for MPAe and the other half for EISCAT).
The main research areas covered are:
Langmuir wave turbulence
ELF and VLF wave research
Effects of Gyroharmonic heating
There is a list of publications that have come out of this facility since its construction in 1979.
Technical Description:
Transmitters
12 linear class AB tetrode tube power amplifiers of 100 kW continuous rating each, driven by a 1.5 kW solid state wideband exciter. Minimum pulse length is about 20uS. Any frequency in the range 3.85-8 MHz can be tuned, but we have been allocated the following: 4.04, 4.544, 4.9128, 5.423, 6.77, 6.96, 7.1, 7.953 MHz. The transmitters can be tuned up either uniformly or to different frequencies in 2 groups of 6, 3 groups of 4, 6 groups of 2, or 12 different frequencies.
Antennas
There is a choice of 3 arrays. Two of the arrays (numbers 2 and 3) have 6x6 crossed dipoles, resulting in 36 antennas. They cover the frequency range 3.85-5.65 MHz and 5.5-8 MHz. The gain of these is 24 dBi giving a half power beamwidth of 14.5 deg and a maximum effective radiated power of 300 MW. A pair of transmitters is fed to orthogonal antennas on a row of antennas. A third array (array 1), covering 5.5-8 MHz, has a gain of 30 dBi giving 1200 MW of effective rad iated power. A pair of transmitters in this array feeds two rows of antennas. Each row has 12 crossed dipoles giving a total of 144 antennas. A particular transmitter can be connected to only one particular row (or pair of rows in array 1), but in any array independent of the other transmitters. The transmitters feed the antennas through about 50 km of aluminium co-axial transmission line.
Control system
Tuning to a new frequency is done by a small microcomputer and can take a few minutes. Tilting of the beam in the north-south plane up to about +/- 30 deg is possible. Power can be chosen in 2.5% steps of the maximum tuned power, which itself can be less than the maximum possible. Complicated amplitude modulation formats are possible under computer or other sources of control. Modulation frequencies in the range 15-200 Hz with duty cyles near 50% can not be used due to power supply resonance problems. The radiated wave can be linearly or circularly polarized with either sense of rotation. Polarization reversal can be achieved on a pulse to pulse basis. Accurate timing to within microseconds is possible. Frequency stability is as good as the EISCAT cesium beam reference.
Dynasonde
A digital HF sounder covering ca. 1-30 MHz is also available. This can be run like an ionosonde or in other modes such as fixed frequency soundings. Spaced receiving antennas are used. A sample ionogram shows a "clean" ionospheric trace. The latest soundings may also be available, but this is still experimental as yet. The Dynasonde does not run continuously so do not be surprised if the latest is not so recent.
There is a list of all soundings recorded since November 1992 when the computer was upgraded to a PC.
http://www.linmpi.mpg.de/english/projekte/heating/
============
This webpage is a list of all the publications in journals produced by this facility. http://www.eiscat.uit.no/heating/htrefs.html
If one takes the time to look at the gist of the titles, some do have hypertext links provided to take you to webpage that has the article, one could see that ionospheric HF heating and definitely shows up on radars, especially as types of backscatter.
This title, from 2000, Triggering of local substorm activation by powerful HF radio waves, Proc. 5th International Conference on Substorms, St. Petersburg, Russia, 16-20 May 2000, ESA SP-443, p.477-480, 2000. (Blagoveshchenskaya, N. F., V.A. Kornienko, T.D. Borisova, B. Thide, M.J. Kosch, M.T. Rietveld, E.V. Mishin, R.Yu. Luk'yanova, and O.A. Troshichev, ) could say alot own its own. There isn't a hypertext link and I am going to see if I can't at least find an abstract by cross indexing my scientific journals database.
I added some technical information regarding the explanation of the ionosphere, the heating of the ionosphere, radar aurora, Incoherent scatter.
I am not trying to be patronizing, I just do not care to paraphrase physics, lol.
Space Physics Textbook http://www.oulu.fi/~spaceweb/textbook/
Space physics is interested in the natural plasma environments found close enough to the Earth to be studied by in situ measurements.
Today, these in situ measurement cover most of the heliosphere. Space physics studies Sun (and its extension, the solar wind) and all planets with plasma environments, including Earth.
One of the main tasks in space physics is to explain the Solar wind - magnetosphere - ionosphere - atmosphere coupling that is responsible for many important phenomena.
Magnetospheric/ionospheric phenomana can be studied by satellites, rockets, and ground based instruments (like radars).
Information taken from http://www.oulu.fi/~spaceweb/textbook/ionosphere.html
Ionosphere (Earth's)
spaceweb@oulu.fi - last update: 6 November 2002 (RR)
Introduction
Because of the Sun 's UV radiation, Earth 's upper atmosphere is partly (0.1% or less) ionized plasma at altitudes of 70-1500 km. This region, ionosphere, is coupled to both the magnetosphere and the neutral atmosphere. It is of great practical importance because of its effect on radio waves.
The existense of a conducting layer in the upper atmosphere results also in many other interesting phenomena. Around the plasma density maximum (F-layer, see below) a so-called ionospheric waveguide is formed for magnetosonic waves. In addition, a so-called ionospheric Alfvén resonator (IAR) can be formed between the density maximum and an upper altitude at about 3000 km, where the Alfvén velocity has a maximum. A third natural resonator is formed between the nearly perfectly conducting terrestrial surface and the ionosphere, creating the so-called Schumann resonances
Ionospheric layers
Ionization appears at a number of atmospheric levels, producing layers or regions which may be identified by their interaction with radio waves. These layers are known as the D, E, and F layers, and their locations are shown in the figure for both night and day conditions at mid-latitudes.
The first ionospheric layer found was the so called E layer or region at about 110 km altitude. It is used by radio operators as a surface from which signals can be reflected to distant stations. It is interesting to note that this works also the other way round and, for example, the auroral kilometric radiation created by the precipitating particles high above the ionosphere does not reach the ground because of the ionospheric E layer. Above the E layer, a F layer consisting of two parts can be found: F1 is at about 170 km, and F2 at about 250 km altitude. Also F layer reflects radio waves. The lowermost region of the ionosphere below 80 km altitude, D layer, however, principally absorbs radio waves.
Density changes
Within the auroral oval the nighttime E layer plasma densities can be much higher than indicated by the figure. Densities are also very variable because of the spatial and temporal strucuture in the ionizing particle precipitation. The E layer plasma density profiles can also be drastically altered due to the occasional formation of so-called sporadic E layers.
In F layer altitudes one encounters such features as polar cap ionization patches and different types of troughs.
Note also that there is also a clear solar cycle effect seen: the average densities are higher during solar maximum years than during the minimum years.
Ionospheric conductivities
...
Ionospheric temperatures
The electron temperature responds readily to the auroral precipitation with a strong increase. Ion temperatures, on the other hand, are elevated mainly by frictional heating due to strong electric fields. The electric field can increase E layer electron temperature only indirectly via instabilities it creates (see radar aurora).
Ionospheric convection
Ionospheric electric fields are the main result of the coupling between the magnetosphere and ionosphere. While at low-latitudes the ionospheric plasma is co-rotating with the Earth, at higher latitudes it is convecting under the influence of the large scale magnetospheric electric field mapped to low altitudes. The Harang discontinuity is one of the ionospheric features related to the plasma convection pattern.
Ionospheric currents
The convection pattern leads to ionospheric Hall currents (see E x B drift), and along the auroral oval so-called convection electrojets are formed at about 100 km altitude: eastward electrojet on the duskside, westward on the dawnside. Historically a term DP-2 has also been used (disturbance polar of the second type).
The coupling between the ionosphere and magnetosphere results also into large and small scale field-aligned currents (FAC). As the down- and upward parts of the current systems are typically separated, horisontal current systems must be formed within the conducting ionosphere. The auroral (or substorm) electrojet, earlier known as the DP-1 current (disturbance polar of the first type), relates to the formation of substorm current wedge.
Ionospheric research
One of the best instruments to study ionosphere with is the incoherent scatter radar, of which EISCAT is a good example. Plasma instabilities are best studied with coherent scatter radars, and ionosondes are still used continuously to monitor ionospheric processes. Ionospheric currents are traditionally been studied by magnetometers.
--------------------
Information taken from
......http://www.oulu.fi/~spaceweb/textbook/radar_aurora.html
Radar aurora
spaceweb@oulu.fi - last update: 18 September 1998, 0830 UT (RR
Introduction
Strong currents, electrojets, found in both equatorial and high latitude ionosphere, lead to plasma instabilities that can be measured directly by electric field wave instruments carried by rockets, or by coherent radars as different kind of Doppler spectra (Kelley, 1989, pp. 396-419). At high latitudes, the E-region auroral electrojets and field-aligned currents produce 'radar aurora' that are somewhat more complicated than the equatorial radar echoes. In both regions, the two primary plasma instabilities are the two-stream and gradient drift instabilities, and the corresponding echoes are referred to as type 1 and type 2, respectively. The two stream instability is the fundamental mechanism responsible for direct generation of short wavelength irregularities in the electrojet plasma. In addition, at auroral altitudes, there is evidence for a third mode (type 3), which is thought to be related to ion cyclotron waves and field-aligned currents especially at the edges of auroral arcs. Recently, however, doubts have been raised against this EIC theory, and it has been proposed that type 3 echoes might be due to type 1 waves originating in narrow sporadic Es layers located at lower electrojet altitudedes (Haldoupis et. al., 1992). Type 4 echoes are a special type of two-stream events associated with anomalous electron heating by the auroral electrojet waves. Echoes labeled as type 5 have been observed by Haldoupis and Nielsen (1989).
For a recent review, see Sahr and Fejer (1996).
Type 4 echoes
Type 4 echoes are relatively rare, short lived (from several seconds to several minutes) and variable, and are observed during strongly driven conditions of ion acoustic wave generation (e.g., Haldoupis et. al., 1991, where the main properties of these echoes are discussed together with the shortcomings of the present theories). They are releted to electron temperature enhancements around an altitude of 110 km. These enhancements are not connected with auroral particle precipitation, since they are much too large (e.g., from 300 K to 1500 K), and because no correlation with electron densities can be found (Wickwar et. al., 1981). Heat conduction from above can be eliminated just from the fact that Te maximizes in the middle of the E - region, and since Ti < Te, the ion population cannot heat the electrons. The correlation with higher-altitude ion temperature indicates a relationship with Joule heating. This relationship must be indirect, since the Joule heating of electrons is negligibly small. One possibility is some kind of plasma instability driven by strong convection electric field, like vd = ve-vi dependent modified two-stream (MTSI, Farley-Buneman) instability. This instability is also confined to region around 110 km, where we find large Hall currents in combination with as low a collision frequency as possible (Schlegel and St.-Maurice, 1981). Electron heating rate due to wave heating is modeled, e.g., by Robinson (1986),
Q = Ne me n* (vd-c)^2
where n* is the anomalous or effective collision frequency (due to scattering of the electrons by the unstable waves; term electron-plasmon collision frequency is used by Jones et. al., 1991 [plasmons are pseudo-particles representing the waves]), and c is the ion acoustic velocity. Equation is analogous to the expression for the Joule (frictional) heating rate, except that the electron-neutral collision frequence is replaced by n* and the neutral gas velocity by c. In paper by Machida and Goertz (1988) this type of heating is actually called anomalous resistive heating. EISCAT measurements of n*(h) can be found in Igarashi and Schlegel (1987), and a method of calculating it in Jones et. al., 1991. It is most likely just this enhanced effective electron collision frequency that heats the electrons, and not the parallel wave electric fields as proposed by St.-Maurice et. al. (1981). The theory of this instability is complicated, since nonlinear kinetic theory must be used (Robinson and Honary, 1990).
Most heating events of this kind measured by incoherent scatter radars have lasted several minutes, and typically the time resolution has not been very high. Providakes et. al. (1988) present EISCAT measurements with integration time of about 10 seconds, showing very short lived (< 1 min.) heating events. An interesting findind was the very prompt anticorrelation between Ti and ne. The authors argued that they cannot be observing a temporal effect, since the heating is not able to change density in a few seconds (chemical time constant is typically about 30 s or more, and, more importantly, increasing Te should result to decreasing recombination rate; similarly the time constant for increasing plasma pressure that pushes plasma out of the heated region is measured in hours). The observed anticorrelation could thus be a result of rapid convection of depleted, hot, highly unstable regions through the radar beam.
References
Haldoupis, C., and E. Nielsen, Very large phase velocities of non two-stream, meter scale irregularities in the high latitude E region ionosphere, J. Geophys. Res., 94, 13489, 1989.
Haldoupis, C., K. Schlegel, and E. Nielsen, On type 3 auroral VHF coherent radar backscatter, J. Geophys. Res., 97, 4109-4120, 1992.
Haldoupis, C., G. J. Sofko, J. A. Koehler, and D. W. Danskin, A new look at type 4 echoes of radar aurora, J. Geophys. Res., 96, 11353-11362, 1991.
Igarashi K., and K. Schlegel, Electron temperature enhancements in the polar E-region measured with EISCAT, J. atmos. terr. Phys., 49, 273-280, 1987.
Jones, B., P. J. S. Williams, K. Schlegel, T. Robinson, and I. Häggström, Interpretation of enhanced electron temperatures measured in the auroral E-region during the ERRRIS campaign, Ann. Geophysicae, 9, 55-59, 1991.
Kelley, M. C., The Earth's ionosphere: Plasma physics and electrodynamics, Academic Press, 1989.
Machida, S., and C. K. Goertz, Computer simulation of the Farley-Buneman instability and anomalous electron heating in the auroral ionosphere, J. Geophys. Res., 93, 9993-10000, 1988.
Providakes, J., D. T. Farley, B. G. Fejer, J. Sahr, W. E. Swartz, I. Häggström, Å. Hedberg, and J. A. Nordling, Observations of auroral E-region plasma waves and electron heating with EISCAT and a VHF radar interferometer, J. atmos. terr. Phys., 50, 339-356, 1988.
Robinson, T. R., Towards a self-consistent non-linear theory of radar auroral backscatter, J. atmos. terr. Phys., 48, 417-422, 1986.
Robinson, T. R., and F. Honary, A resonance broadening kinetic theory of the modified two-stream instability: Implications for radar auroral backscatter experiments, J. Geophys. Res., 95, 1073-1085, 1990.
Sahr, J. D., and B. G. Fejer, Auroral electrojet plasma irregularity theory and experiment: A critical review of present understanding and future directions, J. Geophys. Res., 101, 26893-26909, 1996.
Schlegel, K., and J. P. St.-Maurice, Anomalous heating of the polar E region by unstable plasma waves 1. Observations, J. Geophys. Res., 86, 1447-1452, 1981.
St.-Maurice, K. Schlegel, and P. M. Banks, Anomalous heating of the polar E region by unstable plasma waves 2. Theory, J. Geophys. Res., 86, 1453-1462, 1981.
Wickwar, V. B., C. Lathuillere, W. Kofman, and G. Lejeune, Elevated electron temperatures in the auroral E layer measured with the Chatanika radar, J. Geophys. Res., 86, 4721-4730, 1981.
================
Information taken from....http://www.oulu.fi/~spaceweb/textbook/incoherent.html
Incoherent scatter
spaceweb@oulu.fi - last update: 18 May 1999, 1400 UT
---------------------------------------------
Introduction
The basic principles of incoherent scatter:
Ionospheric electrons start to oscillate due to the electric field of the radar transmitted wave
Oscillating electrons radiate electromagnetic wave
The frequency of the radiated wave changes according to the movement of each electron
Electrons are partly following the motion of the much heavier ions
Radar observes signal from many electrons simultaneously
Because of the electron movement, spectrum of the observed signal is broad and it has shape which depends, e.g., on the temperature.
The received signal is rich of physical content. From the power and the shape of the spectrum one can determine:
electron density
electron temperature
ion temperature
ion drift speed
collision frequencies between ions and molecules
Several quantities can be calculated, e.g.:
ionospheric electric field
ionospheric electric currents
energy and flux of the precipitating particles
Incoherent scatter is succesfully used by several radars, including EISCAT , to study Earth 's ionosphere.
Effects of strong electric fields
Under the influence of a strong electric field the directed component of the ion velocity may become comparable to the thermal speed yielding anisotropic and non-Maxwellian velocity distribution. This, in turn, may affect the analysis of incoherent scatter radar measurements!
Sorry if I bored everyone with the technical things, Sonya |
| |
|
|
Msredsonya
Joined: 25 Mar 2004
Posts: 3
Location: FL |
|
Sat Mar 27, 2004 8:45 am
|
|
|
I posted this an hour ago and I haven't seen it show up on the board yet , so I am sorry if it somehow got posted to another board (eeks) or if it shows up as a duplicate! (yikes)
Obviously space physics relies on radars to study the mechanics of space physics but what does the word RADAR actually stand for ? Radio Detection and Ranging. What does it refer to? The use of radio waves to detect objects and determine the distance (range) to the object.
Radars emit radio pulses that are comprised of oscillating electric and magnetic fields but the pulses have different scattering characteristics, depending on whether the electric fields oscillate horizontally or vertically, some can even spiral during propagation.
The radio pulses emitted can be very powerful because they are ampliflied by the transmitter, in some cases as high as 1 MegaWatt, i.e. 1 million watts peak power. Reference, the standard house light bulb draws about 60 watts, and a toaster draws about 1000 watts.
Additionally, not all the pulse transmission is absorbed or reflected back from the object it is targeting. Some continues to go through the object or around it. Especially in scattering targets (rain, insects, birds, the air).
So I can see where Mojo can bring up the point that radars emit radio waves/frequencies/power.
Why would they rely on radars to see the effects of space physics if nothing was going to be seen/happen on the radar?
Why would they have developed radars, Windprofiler radars, that can measure other levels of the atmosphere besides the previously known ionosphere, such as the tropospheric and stratospheric atmosphere if they weren't not going to be able to see the effects manifested on the radar? These radars usually work at frequencies of around 50 MHz.
excerpt taken from website listed below...."Space physics studies the Sun (and its extension, the solar wind) and all planets with plasma environments, including Earth. One of the main tasks in space physics is to explain the Solar wind - magnetosphere - ionosphere - atmosphere coupling that is responsible for many important phenomena." end of excerpt....
Space physics does includes the study of the ionosphere) The ionosphere is special in that it can REFLECT radio waves....(HAARP is a ionosphere heating instrument. There are several ionosphere heaters world wide. I will post a list and what information I have accumulated to date at a later time as I do not have the research I have been doing on worldwide ionosphere heaters at my fingertips. Why have I been doing the research, because obviously if one beaming ionospheric heater can effect the atmosphere than what happens when you add all the OTHER ionospheric heaters into the picture !)
This website, a scientific one, is just one example of a another (HAARP) ionospheric heater in another country. EISCAT is their own special incoherent scatter radar for their study of the effect of their ionospheric heating.
EISCAT's ionospheric Heating facility including Dynasonde
The Heating facility is situated in Ramfjordmoen, near Tromso in northern Norway, next to the EISCAT UHF and VHF incoherent scatter radars. The facility was built by the Max-Planck-Institut fur Aeronomie in collaboration with the University of Tromso in 1979. In January 1993 the facility was transferred to EISCAT, but the institute still is one of its major users.
The facility is used to conduct plasma physics and active geophysical research of the lower and upper ionosphere by the controlled injection of powerful HF (4-8 MHz) waves. A technical description is given below.
Scientists from MPAe who are closely involved in Heating experiments are: T. Hagfors, H. Kohl, M. T. Rietveld, P. Stubbe, as well as guest scientists and collaborators. (M. Rietveld works half his time for MPAe and the other half for EISCAT).
The main research areas covered are:
Langmuir wave turbulence
ELF and VLF wave research
Effects of Gyroharmonic heating
There is a list of publications that have come out of this facility since its construction in 1979.
Technical Description:
Transmitters
12 linear class AB tetrode tube power amplifiers of 100 kW continuous rating each, driven by a 1.5 kW solid state wideband exciter. Minimum pulse length is about 20uS. Any frequency in the range 3.85-8 MHz can be tuned, but we have been allocated the following: 4.04, 4.544, 4.9128, 5.423, 6.77, 6.96, 7.1, 7.953 MHz. The transmitters can be tuned up either uniformly or to different frequencies in 2 groups of 6, 3 groups of 4, 6 groups of 2, or 12 different frequencies.
Antennas
There is a choice of 3 arrays. Two of the arrays (numbers 2 and 3) have 6x6 crossed dipoles, resulting in 36 antennas. They cover the frequency range 3.85-5.65 MHz and 5.5-8 MHz. The gain of these is 24 dBi giving a half power beamwidth of 14.5 deg and a maximum effective radiated power of 300 MW. A pair of transmitters is fed to orthogonal antennas on a row of antennas. A third array (array 1), covering 5.5-8 MHz, has a gain of 30 dBi giving 1200 MW of effective rad iated power. A pair of transmitters in this array feeds two rows of antennas. Each row has 12 crossed dipoles giving a total of 144 antennas. A particular transmitter can be connected to only one particular row (or pair of rows in array 1), but in any array independent of the other transmitters. The transmitters feed the antennas through about 50 km of aluminium co-axial transmission line.
Control system
Tuning to a new frequency is done by a small microcomputer and can take a few minutes. Tilting of the beam in the north-south plane up to about +/- 30 deg is possible. Power can be chosen in 2.5% steps of the maximum tuned power, which itself can be less than the maximum possible. Complicated amplitude modulation formats are possible under computer or other sources of control. Modulation frequencies in the range 15-200 Hz with duty cyles near 50% can not be used due to power supply resonance problems. The radiated wave can be linearly or circularly polarized with either sense of rotation. Polarization reversal can be achieved on a pulse to pulse basis. Accurate timing to within microseconds is possible. Frequency stability is as good as the EISCAT cesium beam reference.
Dynasonde
A digital HF sounder covering ca. 1-30 MHz is also available. This can be run like an ionosonde or in other modes such as fixed frequency soundings. Spaced receiving antennas are used. A sample ionogram shows a "clean" ionospheric trace. The latest soundings may also be available, but this is still experimental as yet. The Dynasonde does not run continuously so do not be surprised if the latest is not so recent.
There is a list of all soundings recorded since November 1992 when the computer was upgraded to a PC.
http://www.linmpi.mpg.de/english/projekte/heating/
============
This webpage is a list of all the publications in journals produced by this facility. http://www.eiscat.uit.no/heating/htrefs.html
If one takes the time to look at the gist of the titles, some do have hypertext links provided to take you to webpage that has the article, one could see that ionospheric HF heating and definitely shows up on radars, especially as types of backscatter.
This title, from 2000, Triggering of local substorm activation by powerful HF radio waves, Proc. 5th International Conference on Substorms, St. Petersburg, Russia, 16-20 May 2000, ESA SP-443, p.477-480, 2000. (Blagoveshchenskaya, N. F., V.A. Kornienko, T.D. Borisova, B. Thide, M.J. Kosch, M.T. Rietveld, E.V. Mishin, R.Yu. Luk'yanova, and O.A. Troshichev, ) could say alot own its own. There isn't a hypertext link and I am going to see if I can't at least find an abstract by cross indexing my scientific journals database.
I added some technical information regarding the explanation of the ionosphere, the heating of the ionosphere, radar aurora, Incoherent scatter.
I am not trying to be patronizing, I just do not care to paraphrase physics, lol.
Space Physics Textbook http://www.oulu.fi/~spaceweb/textbook/
Space physics is interested in the natural plasma environments found close enough to the Earth to be studied by in situ measurements.
Today, these in situ measurement cover most of the heliosphere. Space physics studies Sun (and its extension, the solar wind) and all planets with plasma environments, including Earth.
One of the main tasks in space physics is to explain the Solar wind - magnetosphere - ionosphere - atmosphere coupling that is responsible for many important phenomena.
Magnetospheric/ionospheric phenomana can be studied by satellites, rockets, and ground based instruments (like radars).
Information taken from http://www.oulu.fi/~spaceweb/textbook/ionosphere.html
Ionosphere (Earth's)
spaceweb@oulu.fi - last update: 6 November 2002 (RR)
Introduction
Because of the Sun 's UV radiation, Earth 's upper atmosphere is partly (0.1% or less) ionized plasma at altitudes of 70-1500 km. This region, ionosphere, is coupled to both the magnetosphere and the neutral atmosphere. It is of great practical importance because of its effect on radio waves.
The existense of a conducting layer in the upper atmosphere results also in many other interesting phenomena. Around the plasma density maximum (F-layer, see below) a so-called ionospheric waveguide is formed for magnetosonic waves. In addition, a so-called ionospheric Alfvén resonator (IAR) can be formed between the density maximum and an upper altitude at about 3000 km, where the Alfvén velocity has a maximum. A third natural resonator is formed between the nearly perfectly conducting terrestrial surface and the ionosphere, creating the so-called Schumann resonances
Ionospheric layers
Ionization appears at a number of atmospheric levels, producing layers or regions which may be identified by their interaction with radio waves. These layers are known as the D, E, and F layers, and their locations are shown in the figure for both night and day conditions at mid-latitudes.
The first ionospheric layer found was the so called E layer or region at about 110 km altitude. It is used by radio operators as a surface from which signals can be reflected to distant stations. It is interesting to note that this works also the other way round and, for example, the auroral kilometric radiation created by the precipitating particles high above the ionosphere does not reach the ground because of the ionospheric E layer. Above the E layer, a F layer consisting of two parts can be found: F1 is at about 170 km, and F2 at about 250 km altitude. Also F layer reflects radio waves. The lowermost region of the ionosphere below 80 km altitude, D layer, however, principally absorbs radio waves.
Density changes
Within the auroral oval the nighttime E layer plasma densities can be much higher than indicated by the figure. Densities are also very variable because of the spatial and temporal strucuture in the ionizing particle precipitation. The E layer plasma density profiles can also be drastically altered due to the occasional formation of so-called sporadic E layers.
In F layer altitudes one encounters such features as polar cap ionization patches and different types of troughs.
Note also that there is also a clear solar cycle effect seen: the average densities are higher during solar maximum years than during the minimum years.
Ionospheric conductivities
...
Ionospheric temperatures
The electron temperature responds readily to the auroral precipitation with a strong increase. Ion temperatures, on the other hand, are elevated mainly by frictional heating due to strong electric fields. The electric field can increase E layer electron temperature only indirectly via instabilities it creates (see radar aurora).
Ionospheric convection
Ionospheric electric fields are the main result of the coupling between the magnetosphere and ionosphere. While at low-latitudes the ionospheric plasma is co-rotating with the Earth, at higher latitudes it is convecting under the influence of the large scale magnetospheric electric field mapped to low altitudes. The Harang discontinuity is one of the ionospheric features related to the plasma convection pattern.
Ionospheric currents
The convection pattern leads to ionospheric Hall currents (see E x B drift), and along the auroral oval so-called convection electrojets are formed at about 100 km altitude: eastward electrojet on the duskside, westward on the dawnside. Historically a term DP-2 has also been used (disturbance polar of the second type).
The coupling between the ionosphere and magnetosphere results also into large and small scale field-aligned currents (FAC). As the down- and upward parts of the current systems are typically separated, horisontal current systems must be formed within the conducting ionosphere. The auroral (or substorm) electrojet, earlier known as the DP-1 current (disturbance polar of the first type), relates to the formation of substorm current wedge.
Ionospheric research
One of the best instruments to study ionosphere with is the incoherent scatter radar, of which EISCAT is a good example. Plasma instabilities are best studied with coherent scatter radars, and ionosondes are still used continuously to monitor ionospheric processes. Ionospheric currents are traditionally been studied by magnetometers.
--------------------
Information taken from
......http://www.oulu.fi/~spaceweb/textbook/radar_aurora.html
Radar aurora
spaceweb@oulu.fi - last update: 18 September 1998, 0830 UT (RR
Introduction
Strong currents, electrojets, found in both equatorial and high latitude ionosphere, lead to plasma instabilities that can be measured directly by electric field wave instruments carried by rockets, or by coherent radars as different kind of Doppler spectra (Kelley, 1989, pp. 396-419). At high latitudes, the E-region auroral electrojets and field-aligned currents produce 'radar aurora' that are somewhat more complicated than the equatorial radar echoes. In both regions, the two primary plasma instabilities are the two-stream and gradient drift instabilities, and the corresponding echoes are referred to as type 1 and type 2, respectively. The two stream instability is the fundamental mechanism responsible for direct generation of short wavelength irregularities in the electrojet plasma. In addition, at auroral altitudes, there is evidence for a third mode (type 3), which is thought to be related to ion cyclotron waves and field-aligned currents especially at the edges of auroral arcs. Recently, however, doubts have been raised against this EIC theory, and it has been proposed that type 3 echoes might be due to type 1 waves originating in narrow sporadic Es layers located at lower electrojet altitudedes (Haldoupis et. al., 1992). Type 4 echoes are a special type of two-stream events associated with anomalous electron heating by the auroral electrojet waves. Echoes labeled as type 5 have been observed by Haldoupis and Nielsen (1989).
For a recent review, see Sahr and Fejer (1996).
Type 4 echoes
Type 4 echoes are relatively rare, short lived (from several seconds to several minutes) and variable, and are observed during strongly driven conditions of ion acoustic wave generation (e.g., Haldoupis et. al., 1991, where the main properties of these echoes are discussed together with the shortcomings of the present theories). They are releted to electron temperature enhancements around an altitude of 110 km. These enhancements are not connected with auroral particle precipitation, since they are much too large (e.g., from 300 K to 1500 K), and because no correlation with electron densities can be found (Wickwar et. al., 1981). Heat conduction from above can be eliminated just from the fact that Te maximizes in the middle of the E - region, and since Ti < Te, the ion population cannot heat the electrons. The correlation with higher-altitude ion temperature indicates a relationship with Joule heating. This relationship must be indirect, since the Joule heating of electrons is negligibly small. One possibility is some kind of plasma instability driven by strong convection electric field, like vd = ve-vi dependent modified two-stream (MTSI, Farley-Buneman) instability. This instability is also confined to region around 110 km, where we find large Hall currents in combination with as low a collision frequency as possible (Schlegel and St.-Maurice, 1981). Electron heating rate due to wave heating is modeled, e.g., by Robinson (1986),
Q = Ne me n* (vd-c)^2
where n* is the anomalous or effective collision frequency (due to scattering of the electrons by the unstable waves; term electron-plasmon collision frequency is used by Jones et. al., 1991 [plasmons are pseudo-particles representing the waves]), and c is the ion acoustic velocity. Equation is analogous to the expression for the Joule (frictional) heating rate, except that the electron-neutral collision frequence is replaced by n* and the neutral gas velocity by c. In paper by Machida and Goertz (1988) this type of heating is actually called anomalous resistive heating. EISCAT measurements of n*(h) can be found in Igarashi and Schlegel (1987), and a method of calculating it in Jones et. al., 1991. It is most likely just this enhanced effective electron collision frequency that heats the electrons, and not the parallel wave electric fields as proposed by St.-Maurice et. al. (1981). The theory of this instability is complicated, since nonlinear kinetic theory must be used (Robinson and Honary, 1990).
Most heating events of this kind measured by incoherent scatter radars have lasted several minutes, and typically the time resolution has not been very high. Providakes et. al. (1988) present EISCAT measurements with integration time of about 10 seconds, showing very short lived (< 1 min.) heating events. An interesting findind was the very prompt anticorrelation between Ti and ne. The authors argued that they cannot be observing a temporal effect, since the heating is not able to change density in a few seconds (chemical time constant is typically about 30 s or more, and, more importantly, increasing Te should result to decreasing recombination rate; similarly the time constant for increasing plasma pressure that pushes plasma out of the heated region is measured in hours). The observed anticorrelation could thus be a result of rapid convection of depleted, hot, highly unstable regions through the radar beam.
References
Haldoupis, C., and E. Nielsen, Very large phase velocities of non two-stream, meter scale irregularities in the high latitude E region ionosphere, J. Geophys. Res., 94, 13489, 1989.
Haldoupis, C., K. Schlegel, and E. Nielsen, On type 3 auroral VHF coherent radar backscatter, J. Geophys. Res., 97, 4109-4120, 1992.
Haldoupis, C., G. J. Sofko, J. A. Koehler, and D. W. Danskin, A new look at type 4 echoes of radar aurora, J. Geophys. Res., 96, 11353-11362, 1991.
Igarashi K., and K. Schlegel, Electron temperature enhancements in the polar E-region measured with EISCAT, J. atmos. terr. Phys., 49, 273-280, 1987.
Jones, B., P. J. S. Williams, K. Schlegel, T. Robinson, and I. Häggström, Interpretation of enhanced electron temperatures measured in the auroral E-region during the ERRRIS campaign, Ann. Geophysicae, 9, 55-59, 1991.
Kelley, M. C., The Earth's ionosphere: Plasma physics and electrodynamics, Academic Press, 1989.
Machida, S., and C. K. Goertz, Computer simulation of the Farley-Buneman instability and anomalous electron heating in the auroral ionosphere, J. Geophys. Res., 93, 9993-10000, 1988.
Providakes, J., D. T. Farley, B. G. Fejer, J. Sahr, W. E. Swartz, I. Häggström, Å. Hedberg, and J. A. Nordling, Observations of auroral E-region plasma waves and electron heating with EISCAT and a VHF radar interferometer, J. atmos. terr. Phys., 50, 339-356, 1988.
Robinson, T. R., Towards a self-consistent non-linear theory of radar auroral backscatter, J. atmos. terr. Phys., 48, 417-422, 1986.
Robinson, T. R., and F. Honary, A resonance broadening kinetic theory of the modified two-stream instability: Implications for radar auroral backscatter experiments, J. Geophys. Res., 95, 1073-1085, 1990.
Sahr, J. D., and B. G. Fejer, Auroral electrojet plasma irregularity theory and experiment: A critical review of present understanding and future directions, J. Geophys. Res., 101, 26893-26909, 1996.
Schlegel, K., and J. P. St.-Maurice, Anomalous heating of the polar E region by unstable plasma waves 1. Observations, J. Geophys. Res., 86, 1447-1452, 1981.
St.-Maurice, K. Schlegel, and P. M. Banks, Anomalous heating of the polar E region by unstable plasma waves 2. Theory, J. Geophys. Res., 86, 1453-1462, 1981.
Wickwar, V. B., C. Lathuillere, W. Kofman, and G. Lejeune, Elevated electron temperatures in the auroral E layer measured with the Chatanika radar, J. Geophys. Res., 86, 4721-4730, 1981.
================
Information taken from....http://www.oulu.fi/~spaceweb/textbook/incoherent.html
Incoherent scatter
spaceweb@oulu.fi - last update: 18 May 1999, 1400 UT
---------------------------------------------
Introduction
The basic principles of incoherent scatter:
Ionospheric electrons start to oscillate due to the electric field of the radar transmitted wave
Oscillating electrons radiate electromagnetic wave
The frequency of the radiated wave changes according to the movement of each electron
Electrons are partly following the motion of the much heavier ions
Radar observes signal from many electrons simultaneously
Because of the electron movement, spectrum of the observed signal is broad and it has shape which depends, e.g., on the temperature.
The received signal is rich of physical content. From the power and the shape of the spectrum one can determine:
electron density
electron temperature
ion temperature
ion drift speed
collision frequencies between ions and molecules
Several quantities can be calculated, e.g.:
ionospheric electric field
ionospheric electric currents
energy and flux of the precipitating particles
Incoherent scatter is succesfully used by several radars, including EISCAT , to study Earth 's ionosphere.
Effects of strong electric fields
Under the influence of a strong electric field the directed component of the ion velocity may become comparable to the thermal speed yielding anisotropic and non-Maxwellian velocity distribution. This, in turn, may affect the analysis of incoherent scatter radar measurements!
Incoherent scatter is succesfully used by several radars, including EISCAT , to study Earth 's ionosphere.
===========
Sorry if I bored everyone with the technical things, Sonya
|
| |
|
|
Mech
Joined: 06 Jun 2001
Posts: 8237
Location: THE 4th REICH USA |
|
Sat Mar 27, 2004 11:59 pm
|
|
|
If you aren't seeing the posts..that means this thread is getting too dense.
A note to Letxa and Mojoman.
Time to wrap up this thread.I plan on locking it soon.
You can start "Anomolies II" if you wish.
This ones about to close.
In a page or two...unless the data falls off earlier.
[Edited 1 times, lastly by Mech on 03-27-2004] |
| |
|
|
electricmojoman
Joined: 07 Feb 2004
Posts: 332
|
|
Sun Mar 28, 2004 4:29 am
|
|
|
Works for me. I've been trying to wrap up for awhile now.
That's a wrap!
How do I get a permission slip to post in the main chemtrail thread?
mojo |
| |
|
|
JerseyBluEyz
Joined: 09 Jul 2003
Posts: 1257
Location: Northeast |
|
Sun Mar 28, 2004 7:06 am
|
|
|
quote:
Originally posted by electricmojoman:
How do I get a permission slip to post in the main chemtrail thread?
Send Thermitt or Mech a PM. They'll give you the rights to post in there. |
| |
|
|
Mech
Joined: 06 Jun 2001
Posts: 8237
Location: THE 4th REICH USA |
|
Sun Mar 28, 2004 7:10 am
|
|
|
I don't have the PW |
| |
|
|
Mech
Joined: 06 Jun 2001
Posts: 8237
Location: THE 4th REICH USA |
|
Sun Mar 28, 2004 7:12 am
|
|
|
Thread closed. |
| |
|
|
 
|
|
 Goto page Previous
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
All times are GMT. The time now is Sat May 26, 2012 10:26 am
|
|
|
|
|
Login
