Polar cap absorption events: Difference between revisions

Revision as of 19:47, 14 August 2018

polar cap absorption event

(Abbreviated PCA event.) A condition in the polar ionosphere where HF and VHF radio waves are absorbed and LF and VLF radio waves are reflected at lower altitudes than normal. PCAs usually originate from major solar storms that launch energetic protons that reach our outer atmosphere quickly and cause excess ionization that distorts the normal refractive properties of the polar ionosphere.

Term edited 14 August 2018.

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 <div class="termentry">
    <div class="term">
-== polar cap absorption events ==
+== polar cap absorption event ==
-  </div>
-<div class="definition"><div class="short_definition">(Abbreviated PCA events.) Episodes of intense [[absorption]] of [[HF]] and  [[VHF]] radio waves over the polar caps caused by excess ionization resulting from an influx of solar  energetic [[particles]] into the [[upper atmosphere]].</div><br/> <div class="paragraph">PCA events have a pronounced [[diurnal]] variation, being much more intense during daytime  than at night, and typically last for two to three days. <br/>''See also'' [[solar proton event]].</div><br/> </div>
+<div class="definition"><div class="short_definition">(Abbreviated PCA event.) A condition in the polar [[ionosphere]] where [[Hf|HF]] and [[Vhf|VHF]] [[radio waves]] are absorbed and [[Lf|LF]] and [[Vlf|VLF]] [[radio waves]] are reflected at lower altitudes than normal. PCAs usually originate from major solar storms that launch energetic [[proton|protons]] that reach our [[outer atmosphere]] quickly and cause excess [[ionization]] that distorts the normal refractive properties of the polar ionosphere.</div><br/> </div>
-</div>
+<p>''Term edited 14 August 2018.''</p>
 {{TermIndex}}