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What is Solar Radio Flux?

  1. Nov 9, 2012 #1
    Referring to following link about Solar Radio Flux, I would like to know more about Solar Radio Flux, is Solar Radio Flux different from Electric Flux? What is the major difference in term of properties of their fluxs?
    Does anyone have any suggested materials on what Solar Radio Flux is about?
    Thanks in advance for any suggestions

    http://www.spaceweather.ca/sx-4-eng.php

    Electric flux is the flux of the electric field. Electric flux is proportional to the number of electric field lines going through a virtual surface.
     
    Last edited: Nov 9, 2012
  2. jcsd
  3. Nov 9, 2012 #2

    Bobbywhy

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    junk0, Welcome to Physics Forums!

    If you go to this Wikipedia page you will find a good description of solar radio flux:
    http://en.wikipedia.org/wiki/Solar_cycle#Solar_radio_flux

    For more details see reference number seventeen.

    If you still are not satisfied Google “solar radio flux”. After all this if you have some doubt, or technical question, or don't understand some part of solar radio flux, then come right back here and post your question. Members of Physics Forums are always ready to assist others who are learning and who show they are true searchers.

    Cheers,
    Bobbywhy
     
  4. Nov 9, 2012 #3
    Referring to your link, I find some description about Solar radio flux.

    Solar radio flux
    Emission from the Sun at centimetric (radio) wavelength is due primarily to coronal plasma trapped in the magnetic fields overlying active regions ... release of magnetic energy driving copious emission of ultraviolet and X-ray radiation as well as energetic particles.

    Another definition
    Flux means the flow of some property through a given area in a given amount of time. The 10.7 solar radio flux is a measure of the solar flux density (amount of solar energy per unit area per unit time) at the 10.7cm wavelength observed at the Earth by radio telescopes called flux monitors. Electric flux measures the change in the electric field. You can think of it as counting the number of electric field lines passing through a given surface over a given period of time. Although solar radio flux and electric flux are both flux measurements, they measure different quantities.

    Referring to following link, it classifies Solar Radio into different Freq in MHZ.
    When they talk about Solar radio flux, I get no idea on how those energetic particles related to wavelength.

    http://www.swpc.noaa.gov/ftpdir/lists/radio/45day_rad.txt [Broken]

    Referring to following link, it talks about Flux Density Values. I am so confused about how to relate energetic particles, wavelength and Flux Density Values together, it seems to me that they are apple and orange, and get no clues on how they related each other, when they use this terminology on Solar Radio Flux.
    http://www.spaceweather.ca/sx-4-eng.php

    Do you have any suggestions?

    Thanks you very much for any suggestions
     
    Last edited by a moderator: May 6, 2017
  5. Nov 9, 2012 #4

    davenn

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    hi junk0

    understand that the sun is, amongst other emissions, a huge radio transmitter, it produces huge amounts of radio signals across a very wide spectrum.

    The solar flux is just a measurement of the strength of the radio signal at 10.7cm wavelength ( approx 2800MHz frequency (10cm =3000MHz))

    basically, Flux = signal strength

    cheers
    Dave
     
    Last edited: Nov 9, 2012
  6. Nov 9, 2012 #5

    Bobbywhy

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    The National Oceanic and Atmospheric Administration at http://www.swpc.noaa.gov/ftpdir/lists/radio/45day_rad.txt [Broken] they quote the solar flux is given in Units: 10^-22 W/m^2/Hz.

    The Canadian Space Weather Forecast Centre in Ottawa at http://www.spaceweather.ca/sx-4-eng.php, uses the same units: The 10.7cm Solar Flux is given in solar flux units (an sfu = 10-22.m-2.Hz-1)

    Details of their solar flux measurements are available at : http://www.spaceweather.ca/data-donnee/sol_flux/sx-3-eng.php

    Both of these agencies report on the Radio Frequency (RF) energy radiated by the sun.
    In neither is there is any mention of energetic particles. Are you perhaps confusing solar flux with “solar wind”? This is a flux of energetic particles emitted by our sun which interacts with our Earth’s magnetosphere.

    Cheers,
    Bobbywhy
     
    Last edited by a moderator: May 6, 2017
  7. Nov 9, 2012 #6
    The History of the 10.7cm Solar Flux

    The history of the 10.7cm Solar Flux is intimately tied in with the beginnings of Canadian radio astronomy. Immediately after the Second World War, Arthur Covington and his colleagues at the National Research Council in Ottawa used bits of military surplus radar and test equipment to make a radio telescope. The antenna was a 4ft (1.2m) paraboloid from a Type IIIC Gun Laying Radar, mounted on a prototype mount casting for a Model 268 radar. By leaning the mount so that the azimuth axis was pointed at the Pole Star, it was converted into a simple polar mount, which made tracking the Sun much easier. The receiver was a Dicke switching receiver used during the war to test silicon mixer crystals for radar applications. The radar system operated at a frequency of 2800MHz, that is a wavelength of 10.7cm.

    http://www.spaceweather.ca/data-donnee/sol_flux/sx-2-eng.php

    solar.jpg

    Solar Radio Flux Monitor provides measures of the whole-disc 10.7cm solar flux.



    Referring to above statement, does 10.7cm wavelength has anything to do with those energetic particles?

    Does anyone have any suggestions on why 10.7cm wavelength is so important as it compares with other wavelength?

    Additional, referring to another link, Solar Radio is classified into different Freq in MHZ.

    Does anyone know what kind of energetic particles with different Freq (wavelength) are talking about?
    If they select a wavelength of 10.7cm to be observed, does it have anything to do with the Freq of those energetic particles? and make a wavelength of 10.7cm to be more representative for strength of solar flux.

    http://www.swpc.noaa.gov/ftpdir/lists/radio/45day_rad.txt [Broken]

    Furthermore,

    Referring to following linked videos,

    Based on the description on Electric Flux, I would like to know what different quantities are between solar radio flux and electric flux.

    Introduction to Electric Flux


    Flux Through a Closed Surface
    http://www.youtube.com/watch?v=ha4l-0VbJuE&feature=relmfu

    Does anyone have any suggestions?

    Thanks everyone very much for any suggestions
     
    Last edited by a moderator: May 6, 2017
  8. Nov 9, 2012 #7

    davenn

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    you seem to be really hung up on "energetic particles" I dont know why ? let it go :)

    its a Radio Signal
    As I said in my earlier post, the flux is the converted signal strength of that radio signal at 2800MHz using this .... 1 SFU = 10-22 W/m2/Hz

    cheers
    Dave
     
  9. Nov 9, 2012 #8

    Bobbywhy

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    Your question about “energetic particles” seems to be from the referenced citation in post #2: http://en.wikipedia.org/wiki/Solar_cycle#Solar_radio_flux

    “The solar magnetic field structures the corona, giving it its characteristic shape visible at times of solar eclipses. Complex coronal magnetic field structures evolve in response to fluid motions at the solar surface, and emergence of magnetic flux produced by dynamo action in the solar interior. For reasons not yet understood in detail, sometimes these structures lose stability, leading to coronal mass ejections into interplanetary space, or flares, caused by sudden localized release of magnetic energy driving copious emission of ultraviolet and X-ray radiation as well as energetic particles. These eruptive phenomena can have a significant impact on Earth's upper atmosphere and space environment, and are the primary drivers of what is now called space weather.”

    These solar emissions are NOT electromagnetic radiation in the radio frequency band. They consist of Ultraviolet, X-ray, and Energetic particles. You may read about the energetic particles at:
    http://en.wikipedia.org/wiki/Solar_energetic_particles
    http://en.wikipedia.org/wiki/Solar_wind

    Since you have shown you clearly understand the definition of electric flux, that is the rate of transfer of energy through a surface, you may rest assured that other forms of radiated energy, including energetic particles as they pass through a surface, are also described as a flux.

    Cheers,
    Bobbywhy
     
  10. Nov 9, 2012 #9
    Referring to following definition on electric flux and radio signal, does anyone have any suggestions how they interact to each other?

    For example,
    can radio signal generate electric flux? or
    can electric flux generate radio signal?

    In electromagnetism, electric flux is the flux of the electric field. Electric flux is proportional to the number of electric field lines going through a virtual surface. In other words the number of electric lines of force passing through the given surface area which is held perpendicular to the direction of electric lines of force is called electric flux.

    http://en.wikipedia.org/wiki/Electric_flux

    Radio is the transmission of signals through free space by electromagnetic radiation of a frequency significantly below that of visible light, in the radio frequency range, from about 30 kHz to 300 GHz.[1] These waves are called radio waves. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.

    http://en.wikipedia.org/wiki/Radio

    Flux.jpg

    Flux = signal strength
    Could you please tell me more about what actually objects are measured in term of strength?
    Will the strength refer to the Freq of Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space?

    Furthermore, referring to above linked image, based on the freq classification of radio flux, will higher Freq generate higher electric flux?

    Does anyone have any suggestions?
    Thanks everyone very much for any suggestions
     
  11. Nov 10, 2012 #10
    Solar energetic particles
    "Solar energetic particles (SEP) are high-energy particles coming from the Sun, which consist of protons, electrons, and heavy ions with energy ranging from a few tens of keV to GeV (the fastest particles can reach speed up to 80% of the speed of light). They are of particular interest and importance because they can endanger life in outer space (especially particles above 40 MeV)."

    When they talk about high-energy particles, what do high-energy refer to? in term of Freq of oscillating electromagnetic fields or amount of charged particles. will it be higher Electromagnetic radiation based on following definition? In the other words, does high energy refer to high frequencies?

    Electromagnetic radiation
    Electromagnetic radiation (EM radiation or EMR) is a form of energy emitted and absorbed by charged particles, which exhibits wave-like behavior as it travels through space. EMR has both electric and magnetic field components, which stand in a fixed ratio of intensity to each other, and which oscillate in phase perpendicular to each other and perpendicular to the direction of energy and wave propagation. In a vacuum, electromagnetic radiation propagates at a characteristic speed, the speed of light.

    http://en.wikipedia.org/wiki/Electromagnetic_radiation

    http://www.youtube.com/watch?v=4CtnUETLIFs&feature=fvwrel

    As we know, electric and magnetic field must exist together, will higher MeV particles generate higher magnetic field? Will higher MeV particles affect the Freq of oscillating electromagnetic fields?

    On the other words
    One solar flux unit = 10−22 watt per square meter-hertz
    In units, does watt represent how much charges particles is? Can it be measured in MeV?
    I get no idea on what square meter-hertz is represented, does anyone have any suggestions?

    Flux = signal strength in term of:
    (1) Higher Flux = Higher MeV particles
    (2) Higher Flux = Higher Freq of oscillating electromagnetic fields
    (3) Both (1) and (2), which implies that Higher Flux = Higher MeV particles = Higher Freq of oscillating electromagnetic fields
    (4) None of above is correct


    Does anyone have any suggestions on which one is the correct answer?

    Thanks everyone very much for any suggestions
     
  12. Nov 10, 2012 #11

    davenn

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    They are charged particles, not E/M radiation, as given in the first sentance of the quote you pasted. Also including neutrinos.
    Now there is high energy E/M radiation too eg cosmic rays, X-rays and gamma rays.
    I'm not sure ( without looking up) dont think cosmic rays are electromagnetic. But Xrays and Gamma rays are.


    none of the above--- AGAIN I repeat, the solar flux is a measurement of the radio emission signal strength of the sun at 2800MHz. That signal strength is then converted to SFU's using the formula already given above


    Dave
     
  13. Nov 10, 2012 #12
    Definition for Solar Radio Flux

    "The radiant flux per unit wavelength or frequency interval per unit solid angle per unit of projected area of the source; the usual unit is watt per nanometer per steradian per square meter."

    http://www.answers.com/topic/spectral-radiance

    "Radiance and spectral radiance are measures of the quantity of radiation that passes through or is emitted from a surface and falls within a given solid angle in a specified direction ... Radiance characterizes total emission or reflection. Radiance is useful because it indicates how much of the power emitted by an emitting or reflecting surface will be received by an optical system looking at the surface from some angle of view. In this case, the solid angle of interest is the solid angle subtended by the optical system's entrance pupil. Since the eye is an optical system, radiance and its cousin luminance are good indicators of how bright an object will appear."

    http://en.wikipedia.org/wiki/Spectral_radiance

    Definition for Solar energetic particles

    "Solar energetic particles (SEP) are high-energy particles coming from the Sun, which consist of protons, electrons, and heavy ions with energy ranging from a few tens of keV to GeV (the fastest particles can reach speed up to 80% of the speed of light). They are of particular interest and importance because they can endanger life in outer space (especially particles above 40 MeV)."


    Solar Radio Flux
    Units: 10-22 W/m2/Hz

    Solar Radio Flux are charged particles (Solar energetic particles), which is a measurement of the radio emission signal strength of the sun at 2800MHz, 2800MHz comes from "The radar system operated at a frequency of 2800MHz, that is a wavelength of 10.7cm."

    Referring to following image, it is the report to measure Solar Radio Data, but I don't understand why the measured objects - Solar energetic particles are measured in term of Freq MHz instead of MeV, furthermore, data is classified into different Freq for measurement.

    On the other hands, [Please correct me if I am wrong], Solar Radio Flux is measured on Earth's surface in order to estimate the radio emission signal strength of the sun at 2800MHz, since Earth are protected with magnetic field, and most charged particles are shift toward North Pole, if this statement is correct, the measured results of Solar Radio Flux will be different between South Pole and North Pole, it implies that different locations will receive different strength of signals based on different latitude levels, does anyone know how scientists solve this standard issues for monitoring Solar Radio Flux?

    Flux.jpg

    http://www.swpc.noaa.gov/ftpdir/lists/radio/45day_rad.txt [Broken]

    Does anyone have any suggestions?

    Thanks everyone very much for any suggestions
     
    Last edited by a moderator: May 6, 2017
  14. Nov 10, 2012 #13

    davenn

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    Its getting a little frustrating telling you the same thing over and over again

    this is the last time I will respond to you, I dont know why you are not listening to what you are being told ?

    for the last time PLEASE ... I repeat ...
    none of the above--- AGAIN I repeat, the solar flux is a measurement of the radio emission signal strength of the sun at 2800MHz. That signal strength is then converted to SFU's using the formula already given above

    forget about this hangup you have with energetic particles, the sun emits lots of them, BUT they are NOT part of the 2800MHz solar flux reading!!


    Dave
     
    Last edited: Nov 10, 2012
  15. Nov 10, 2012 #14


    I can accept the answer on above statement, but the root cause deep inside my heart is that I don't know what objects are measuring to determine / estimate the radio emission signal strength of the sun at 2800 MHz, if energetic particles are NOT part of the 2800MHz solar flux reading, which make me very confusing.

    For example, I need to determine whether this location is good to open a store or not, and need to study about the strength for business opportunity within this area, since there are many factors to affect business, but I mainly select the number of people walking on this location during office hours to be the success factor for measurement, so my assumption on the strength for business opportunity is based on the number of people walking on this location during office hour, which is the same type of answer I am looking for from Solar Radio Flux. I need to understand what assumption is to estimate the radio emission signal strength of the sun at 2800 MHz, what objects are observing and measuring in order to estimate the radio emission signal strength of the sun at 2800 MHz.

    Does anyone have any suggestions?

    Thanks everyone very much for any suggestions
     
  16. Nov 10, 2012 #15

    davenn

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    OK none of you statement makes sense

    I have absolutely no idea what these objects are that you refer to

    If you cannot accept that the solar flux is the measured and converted strength of the radio signal received, then there's not much more I can tell you

    ciao

    Dave
     
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