Space Scientists Uncover Causes Of Gap In Van Allen Belts

[yevaud]

<b>A team of British and US scientists have discovered that the gap in the Van Allen radiation belts is formed by natural wave turbulence in space, not by lightning. The discovery settles years of controversy among space scientists about the mechanisms responsible for causing the gap and has important implications for space weather forecasting.</b><br /><br />High above the Earth's atmosphere, energetic charged particles are trapped in the Earth's magnetic field where they form the Van Allen radiation belts. Energetic electrons, travelling close to the speed of light, occupy two doughnut shaped zones, usually separated by a gap known as the slot region.<br /><br />The underlying mechanism that clears the slot region of electrons has been the subject of intense scientific debate. Now, based on analysis of wave data collected over 13 months by the CRRES satellite, Dr Nigel Meredith of British Antarctic Survey and colleagues from BAS, the University of California, Los Angeles and the University of Iowa, believe that the gap is most likely formed by natural wave turbulence in space, rather than by lightning as the alternative theory suggests. Their results are published in the Journal of Geophysical Research this week.<br /><br />According to lead author, Dr Nigel Meredith:<br /><br />"Last year NASA scientists suggested that lightning-generated radio waves leaking out into space are responsible for the gap between the two belts by dumping particles into the atmosphere. Since lightning occurs far more often over land than water, waves in space should also occur more over land. However, after analysing satellite data we found that there is no land-ocean variation at frequencies less than 1 kiloHertz where the waves are most intense. Instead, wave activity increases during geomagnetic disturbances driven by the Sun, suggesting that natural wave turbulence is responsible for the gap."<br /><br />"The results are important, because a better understanding of the radiation belts will h <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[spacester]

This appears to be an important advancement in understanding for the scientists, thanks for posting it.<br /><br />As far as my understanding, not so much. I am having trouble understanding exactly what they mean by "natural space turbulence"<br /><br />The best I can find in the article is:<br /><br /><font color="yellow">One theory maintains that the radio waves are generated locally via natural turbulence in space, arising from particles injected during enhanced magnetic activity driven by the Sun. </font><br /><br />So . . . um . . . the particles are injected into the slot region, and um . . . radio waves are generated locally . . . um by the particles themselves (?) . . . which are in a turbulent flow regime (?) . . . and these radio waves clear the area?<br /><br />So the particles clear themselves out b/c they generate radio waves? Why in the slot region but not above or below?<br /><br />What is 'space turbulence'? Are they using the term literally, such that a Reynolds number is calculated and is a value higher than the critical value where flow transitions from laminar to turbulent? Or are they using the term as an analogy for what is really going on? <div class="Discussion_UserSignature"> </div>

 

[yevaud]

I'm going to make a wild stab in the dark, and say that the "turbulence" is a chaotic relationship between the solar wind and our Magnetosphere. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[spacester]

Wow that was a fast response! <img src="/images/icons/laugh.gif" /><br /><br />OK, the interaction of the solar wind and the magnetosphere is what causes the whole radiation belt phenomena in the first place, right? So that answer strikes me the same as what I got out of the article: it's like they're saying "it is the way it is because that's the way it is." LOL.<br /><br />I have no doubt it is a failing on the part on the writer, not the scientists. <br /><br />BTW I'm not asking you to embark on a research project <img src="/images/icons/laugh.gif" /> , just hoping that someone here can shed some light on this. <div class="Discussion_UserSignature"> </div>

 

[yevaud]

Well, you've seen the "Bow Shock" from the solar wind meeting the Magnetosphere. There is the dynamic where the chaotic behavior creates the gaps. This is not unusual, believe it or not - it's seen routinely in non-linear mathematics, e.g. Chaos Theory. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>