https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&feed=atom&action=historyReflection of Coronal Global Waves - Revision history2024-03-29T12:12:09ZRevision history for this page on the wikiMediaWiki 1.16.0https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=10743&oldid=prevSchriste at 17:39, 22 August 20182018-08-22T17:39:04Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Hugh Hudson</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Hugh Hudson</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = January 13, 2014|previous_nugget = [[Flare Coronal Rain]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = January 13, 2014|previous_nugget = [[Flare Coronal Rain]]</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;">|next_nugget = TBD</del></div></td><td colspan="2"> </td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|number = 217</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|number = 217</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|next_nugget={{#ask: [[Category:Nugget]] [[RHESSI Nugget Index::218]]}}</ins></div></td></tr>
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</table>Schristehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=6585&oldid=prevHhudson: small fixes and a link2014-01-12T16:27:11Z<p>small fixes and a link</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[http://solarphysics.livingreviews.org/open?pubNo=lrsp-2006-2&amp;page=articlesu11.html Type II] event.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[http://solarphysics.livingreviews.org/open?pubNo=lrsp-2006-2&amp;page=articlesu11.html Type II] event.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and reports <del class="diffchange diffchange-inline">the </del>property: the apparently [specular reflection] of the waves at a distant magnetic feature, possibly the domain wall of the south polar </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and reports <ins class="diffchange diffchange-inline">a remarkable </ins>property: the apparently </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[<ins class="diffchange diffchange-inline">http://scienceprimer.com/specular-diffuse-reflection </ins>specular reflection] of the waves at a distant magnetic feature, possibly the domain wall of the south polar </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[http://www.exploratorium.edu/spaceweather/holes.html coronal hole] (see also Ref. [2]).</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[http://www.exploratorium.edu/spaceweather/holes.html coronal hole] (see also Ref. [2]).</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>structure, something only possible with STEREO.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>structure, something only possible with STEREO.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Figure 1 shows an overview of one of the events, T12:01; this was the only one for which a radio type II burst was reported (but, as can be seen in the [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser] summary of the radio observations, all three events had intense type III bursts<del class="diffchange diffchange-inline">.</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Figure 1 shows an overview of one of the events, T12:01; this was the only one for which a radio type II burst was reported (but, as can be seen in the [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser] summary of the radio observations, all three events had intense type III bursts <ins class="diffchange diffchange-inline">-</ins></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">This </del>may or may not be relevant!</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">this </ins>may or may not be relevant!<ins class="diffchange diffchange-inline">).</ins></div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:217f1.png|800px|thumb|center|Fig. 1: </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:217f1.png|800px|thumb|center|Fig. 1: </div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Conclusions ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Conclusions ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>The refraction and reflection of global coronal waves is a necessary consequence of their characteristic description in the MHD framework, as <del class="diffchange diffchange-inline">note </del>long ago in Uchida's original analysis. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The refraction and reflection of global coronal waves is a necessary consequence of their characteristic description in the MHD framework, as <ins class="diffchange diffchange-inline">noted </ins>long ago in Uchida's original analysis. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events of 27 January 2011 that we've described in Ref. [1] provided the cleanest evidence yet that magnetic irregularities can result not only in refraction, as often pointed out, but in apparently exact specular reflection.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events of 27 January 2011 that we've described in Ref. [1] provided the cleanest evidence yet that magnetic irregularities can result not only in refraction, as often pointed out, but in apparently exact specular reflection.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>One puzzle is that the surface of the domain boundary at the polar coronal hole should tilt away from the vertical as the field expands outwards, in a manner inconsistent with the observed angle of reflection.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>One puzzle is that the surface of the domain boundary at the polar coronal hole should tilt away from the vertical as the field expands outwards, in a manner inconsistent with the observed angle of reflection.</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=6581&oldid=prevHhudson: added some links2014-01-10T21:08:32Z<p>added some links</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Introduction ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Introduction ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[Solar flares] and [CMEs] can excite large-scale waves in the corona, observable by many</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[<ins class="diffchange diffchange-inline">https://en.wikipedia.org/wiki/Solar_flare </ins>Solar flares] and [<ins class="diffchange diffchange-inline">https://en.wikipedia.org/wiki/Coronal_mass_ejection </ins>CMEs] can excite large-scale waves in the corona, observable by many techniques with our excellent modern data.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>techniques with our excellent modern data.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>These global waves can in extreme cases produce the [<ins class="diffchange diffchange-inline">http://solarscience.msfc.nasa.gov/chromos.shtml </ins>chromospheric] signature</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>These global waves can in extreme cases produce the [chromospheric] signature</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>that we call a [<ins class="diffchange diffchange-inline">https://en.wikipedia.org/wiki/Moreton_wave </ins>Moreton wave], but since Uchida's early interpretative <ins class="diffchange diffchange-inline">work in </ins>terms of MHD wave propagation, we have understood the chromospheric wave to be a consequence of the global wave itself.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>that we call a [Moreton wave], but since Uchida's early interpretative <del class="diffchange diffchange-inline">workin </del>terms of MHD wave propagation, we have understood the chromospheric wave</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Controversy has raged on and off regarding the relationships between the global waves and their causes</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>to be a consequence of the global wave itself.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>(flare [<ins class="diffchange diffchange-inline">https://en.wikipedia.org/wiki/Blast_wave </ins>blast wave?<ins class="diffchange diffchange-inline">] </ins>or CME [<ins class="diffchange diffchange-inline">https://en.wikipedia.org/wiki/Shock_wave#Bow_Shocks </ins>bow wave?<ins class="diffchange diffchange-inline">]</ins>).</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Controversy has raged on and off regarding the relationships between the global waves and their causes (flare [blast wave<del class="diffchange diffchange-inline">]</del>? or CME [bow wave<del class="diffchange diffchange-inline">]</del>?).</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>In this Nugget we do not discuss the exciters, but only the wave propagation.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>In this Nugget we do not discuss the exciters, but only the wave propagation.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The particular events studied (see Ref. [1]) occurred on 27 January 2011:</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The particular events studied (see Ref. [1]) occurred on 27 January 2011:</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is already interesting, because these are minor flares.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is already interesting, because these are minor flares.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The RHESSI [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The RHESSI [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser]</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>shows them, highlighting the 12:18 event because of its association with a radio [<del class="diffchange diffchange-inline">type </del>II] event.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>shows them, highlighting the 12:18 event because of its association with a radio</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[<ins class="diffchange diffchange-inline">http://solarphysics.livingreviews.org/open?pubNo=lrsp-2006-2&amp;page=articlesu11.html Type </ins>II] event.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and reports the property: the apparently [specular reflection] of the waves at a distant magnetic feature, possibly the domain wall of the south polar coronal hole (see also Ref. [2]).</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and reports the property: the apparently [specular reflection] of the waves at a distant magnetic feature, possibly the domain wall of the south polar </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[http://www.exploratorium.edu/spaceweather/holes.html </ins>coronal hole<ins class="diffchange diffchange-inline">] </ins>(see also Ref. [2]).</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Observations ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Observations ==</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We make use of the EUV images obtained by [STEREO-A] and by [http://proba2.oma.be/ PROBA2]; this </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We make use of the EUV images obtained by [STEREO-A] and by [http://proba2.oma.be/ PROBA2]; this </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>epoch put STEREO-A almost at [quadrature], i.e. with a nearly orthogonal view of the events.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>epoch put STEREO-A almost at [<ins class="diffchange diffchange-inline">https://en.wikipedia.org/wiki/Quadrature_(astronomy) </ins>quadrature], i.e. with a nearly orthogonal view of the events.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events were at the extreme limb as viewed from near the Earth.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events were at the extreme limb as viewed from near the Earth.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>These events are unusual in several ways.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>These events are unusual in several ways.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>'''First''', they arise from quite trivial flare events in NOAA 11149, just at the NW limb on the date of observation - a minor sunspot group.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>'''First''', they arise from quite trivial flare events in NOAA 11149, just at the NW limb on the date of observation - a minor sunspot group.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>The detection of a type II burst from a [GOES] C-class event is noteworthy in its own right, and it is not surprising that only one of these three events could be detected in this manner.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The detection of a type II burst from a [<ins class="diffchange diffchange-inline">http://www.swpc.noaa.gov/today.html </ins>GOES] C-class event is noteworthy in its own right, and it is not surprising that only one of these three events could be detected in this manner.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>'''Second''', there were three events in one day, quite rare; '''third''', they were closely [homologous], a striking property; '''fourth''', the waves impinged almost at right angles to the magnetic boundary of the south polar coronal hole.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>'''Second''', there were three events in one day, quite rare; '''third''', they were closely </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Probably without these factors working so well together, in an otherwise quite [http://www.solarmonitor.org/index.php?date=20110127&region=&indexnum=1 quiet corona], we would not have been able to carry out such a detailed analysis of the wave reflection.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[<ins class="diffchange diffchange-inline">http://www.google.co.uk/search?client=safari&rls=en&q=homologous+flare&ie=UTF-8&oe=UTF-8&gws_rd=cr&ei=ll7QUtzNGKrO0wW1woDwCA </ins>homologous], a striking property; '''fourth''', the waves impinged almost at right angles to the magnetic boundary of the south polar coronal hole.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Probably without these factors working so well together, in an otherwise quite </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[http://www.solarmonitor.org/index.php?date=20110127&region=&indexnum=1 quiet corona], we would not have been able to carry out such a detailed analysis of the wave reflection.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The stereoscopic view afforded by [http://proba2.oma.be/ PROBA2], from its low Earth orbit, allows us to study the reflection in the third dimension.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The stereoscopic view afforded by [http://proba2.oma.be/ PROBA2], from its low Earth orbit, allows us to study the reflection in the third dimension.</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>A simple summary of the kinematics then is shown in Figure 3 for the same event. The primary wave decelerates as it approaches the polar regions (note that all positions and velocities are referred to the surface of the Sun, hence this deceleration is real, rather than the result of foreshortening.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>A simple summary of the kinematics then is shown in Figure 3 for the same event. The primary wave decelerates as it approaches the polar regions (note that all positions and velocities are referred to the surface of the Sun, hence this deceleration is real, rather than the result of foreshortening<ins class="diffchange diffchange-inline">)</ins>.</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:217f3.png|500px|thumb|center|Fig. 3: </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:217f3.png|500px|thumb|center|Fig. 3: </div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=6580&oldid=prevHhudson: added Olmedo reference2014-01-09T15:29:38Z<p>added Olmedo reference</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>that we call a [Moreton wave], but since Uchida's early interpretative workin terms of MHD wave propagation, we have understood the chromospheric wave</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>that we call a [Moreton wave], but since Uchida's early interpretative workin terms of MHD wave propagation, we have understood the chromospheric wave</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>to be a consequence of the global wave itself.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>to be a consequence of the global wave itself.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Controversy has raged on and off regarding the relationships between the <del class="diffchange diffchange-inline">globalwaves </del>and their causes (flare [blast wave]? or CME [bow wave]?).</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Controversy has raged on and off regarding the relationships between the <ins class="diffchange diffchange-inline">global waves </ins>and their causes (flare [blast wave]? or CME [bow wave]?).</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>In this Nugget we do not discuss the exciters, but only the wave propagation.The particular events studied (see Ref. [1]) occurred on 27 January 2011:</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>In this Nugget we do not discuss the exciters, but only the wave propagation.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The particular events studied (see Ref. [1]) occurred on 27 January 2011:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>SOL2011-01-27T08:50 [B6.6], T12:01 [C1.2] , and T20:03 (C1.5), all from the same active region.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>SOL2011-01-27T08:50 [B6.6], T12:01 [C1.2] , and T20:03 (C1.5), all from the same active region.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>This is already interesting, because these are minor flares.The RHESSI [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>This is already interesting, because these are minor flares.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The RHESSI [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>shows them, highlighting the 12:18 event because of its association with a radio [type II] event.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>shows them, highlighting the 12:18 event because of its association with a radio [type II] event.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and reports the property: the apparently [specular reflection] of the waves at a distant magnetic feature, possibly the domain wall of the south polar coronal hole <ins class="diffchange diffchange-inline">(see also Ref. [2])</ins>.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>reports the property: the apparently [specular reflection] of the waves at a distant magnetic feature, possibly the domain wall of the south polar coronal hole.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Observations ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Observations ==</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events of 27 January 2011 that we've described in Ref. [1] provided the cleanest evidence yet that magnetic irregularities can result not only in refraction, as often pointed out, but in apparently exact specular reflection.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events of 27 January 2011 that we've described in Ref. [1] provided the cleanest evidence yet that magnetic irregularities can result not only in refraction, as often pointed out, but in apparently exact specular reflection.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>One puzzle is that the surface of the domain boundary at the polar coronal hole should tilt away from the vertical as the field expands outwards, in a manner inconsistent with the observed angle of reflection.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>One puzzle is that the surface of the domain boundary at the polar coronal hole should tilt away from the vertical as the field expands outwards, in a manner inconsistent with the observed angle of reflection.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Another possibility is that the reflection involves the structure of the polar-crown filament cavity, as note in the [aurora polaris] described in Ref. [<del class="diffchange diffchange-inline">2</del>] and elsewhere.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Another possibility is that the reflection involves the structure of the polar-crown filament cavity, as note in the [aurora polaris] described in Ref. [<ins class="diffchange diffchange-inline">3</ins>] and elsewhere.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is a question that might be resolved by PFSS modeling, which for a quiet corona such as this one may be quite precise.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is a question that might be resolved by PFSS modeling, which for a quiet corona such as this one may be quite precise.</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>* [1] [http://adsabs.harvard.edu/abs/2013SoPh..286..201K STEREO-A and PROBA2 Quadrature Observations of Reflections of Three EUV Waves from a Coronal Hole]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>* [1] [http://adsabs.harvard.edu/abs/2013SoPh..286..201K STEREO-A and PROBA2 Quadrature Observations of Reflections of Three EUV Waves from a Coronal Hole]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>* [2] [http://adsabs.harvard.edu/abs/1996ApJ...470..629H A Long-Duration Solar Flare with Mass Ejection and Global Consequences]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>* [2<ins class="diffchange diffchange-inline">] [http://adsabs.harvard.edu/abs/2012ApJ...756..143O Secondary Waves and/or the "Reflection" from and "Transmission" through a Coronal Hole of an Extreme Ultraviolet Wave Associated with the 2011 February 15 X2.2 Flare Observed with SDO/AIA and STEREO/EUVI]</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">* [3</ins>] [http://adsabs.harvard.edu/abs/1996ApJ...470..629H A Long-Duration Solar Flare with Mass Ejection and Global Consequences]</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[category: nugget]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[category: nugget]]</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=6578&oldid=prevHhudson: completed 1st draft2014-01-09T12:34:51Z<p>completed 1st draft</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Introduction ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Introduction ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">Flares </del>and CMEs can excite large-scale waves in the corona, observable by many</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[Solar flares] </ins>and <ins class="diffchange diffchange-inline">[</ins>CMEs<ins class="diffchange diffchange-inline">] </ins>can excite large-scale waves in the corona, observable by many</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>techniques with our excellent modern data.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>techniques with our excellent modern data.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>These global waves can in extreme cases produce the [chromospheric] signature</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>These global waves can in extreme cases produce the [chromospheric] signature</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>'''First''', they arise from quite trivial flare events in NOAA 11149, just at the NW limb on the date of observation - a minor sunspot group.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>'''First''', they arise from quite trivial flare events in NOAA 11149, just at the NW limb on the date of observation - a minor sunspot group.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The detection of a type II burst from a [GOES] C-class event is noteworthy in its own right, and it is not surprising that only one of these three events could be detected in this manner.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The detection of a type II burst from a [GOES] C-class event is noteworthy in its own right, and it is not surprising that only one of these three events could be detected in this manner.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>'''Second''', there were three events in one day, quite rare; '''third''', they were closely [homologous], a striking property; fourth, the waves impinged almost at right angles to the magnetic boundary of the south polar coronal hole.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>'''Second''', there were three events in one day, quite rare; '''third''', they were closely [homologous], a striking property; <ins class="diffchange diffchange-inline">'''</ins>fourth<ins class="diffchange diffchange-inline">'''</ins>, the waves impinged almost at right angles to the magnetic boundary of the south polar coronal hole.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Probably without these factors working so well together, in an otherwise quite [http://www.solarmonitor.org/index.php?date=20110127&region=&indexnum=1 quiet corona, we would not have been able to carry out such a detailed analysis of the wave reflection.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Probably without these factors working so well together, in an otherwise quite [http://www.solarmonitor.org/index.php?date=20110127&region=&indexnum=1 quiet corona<ins class="diffchange diffchange-inline">]</ins>, we would not have been able to carry out such a detailed analysis of the wave reflection.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The stereoscopic view afforded by [http://proba2.oma.be/ PROBA2], from its low Earth orbit, allows us to study the reflection in the third dimension.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The stereoscopic view afforded by [http://proba2.oma.be/ PROBA2], from its low Earth orbit, allows us to study the reflection in the third dimension.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Figure 2 shows this<del class="diffchange diffchange-inline">,</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Figure 2 shows this <ins class="diffchange diffchange-inline">in the form of stackplots of wavefront position vs. time.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[File:217f2.png|<del class="diffchange diffchange-inline">800px</del>|thumb|center|Fig. 2: </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[File:217f2.png|<ins class="diffchange diffchange-inline">600px</ins>|thumb|center|Fig. 2: </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Stereoscopic views of <del class="diffchange diffchange-inline">two </del>of the events, capturing the third dimension</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Stereoscopic views of <ins class="diffchange diffchange-inline">one </ins>of the events, capturing the third dimension<ins class="diffchange diffchange-inline">;</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">the upper and lower panels show two different heights, as seen from the projection at PROBA2 (position to the right, time increasing vertically upwards).</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The black/yellow arrows show the incident wave, and the blue/white ones the reflected wave.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">A more detailed multi-level study shows good consistency with the specular condition.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">We learned from this stereoscopy that </del>the primary wave <del class="diffchange diffchange-inline">appears most prominently at low altitudes, consistent with </del>the <del class="diffchange diffchange-inline">idea </del>that <del class="diffchange diffchange-inline">the expected vertical increase of Alfven speed should serve </del>to <del class="diffchange diffchange-inline">refract </del>the <del class="diffchange diffchange-inline">wave normal away from the vertical. </del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">A simple summary of the kinematics then is shown in Figure 3 for </ins>the <ins class="diffchange diffchange-inline">same event. The </ins>primary wave <ins class="diffchange diffchange-inline">decelerates as it approaches </ins>the <ins class="diffchange diffchange-inline">polar regions (note </ins>that <ins class="diffchange diffchange-inline">all positions and velocities are referred </ins>to the <ins class="diffchange diffchange-inline">surface </ins>of the <ins class="diffchange diffchange-inline">Sun</ins>, <ins class="diffchange diffchange-inline">hence this deceleration is real, rather than </ins>the <ins class="diffchange diffchange-inline">result </ins>of <ins class="diffchange diffchange-inline">foreshortening</ins>.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">We also learned that the reflected wave emerged with a upwards tilt, i.e. more toward the vertical.</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">The reflection angle was </del>of the <del class="diffchange diffchange-inline">order of 10<sup>o</sup></del>, <del class="diffchange diffchange-inline">consistent with </del>the <del class="diffchange diffchange-inline">angle </del>of <del class="diffchange diffchange-inline">incidence as expected from a specular reflection</del>.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[File:217f3.png|<del class="diffchange diffchange-inline">600px</del>|thumb|center|Fig. 3: </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[File:217f3.png|<ins class="diffchange diffchange-inline">500px</ins>|thumb|center|Fig. 3: </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Kinematics of the T12:01 event, showing the positions of the primary wave and of the reflected wave.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Kinematics of the T12:01 event, showing the positions of the primary wave and of the reflected wave.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">We learned from this stereoscopy that the primary wave appears most prominently at low altitudes, consistent with the idea that the expected vertical increase of Alfven speed should serve to refract the wave normal away from the vertical. </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">We also learned that the reflected wave emerged with a upwards tilt, i.e. more toward the vertical.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">The reflection angle was of the order of 10<sup>o</sup>, consistent with the angle of incidence as expected from a specular reflection.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The detailed kinematics that we can do with these events allows us to study them far from the CME itself; as can be seen in Figure 3, the moment of reflection hapens some 45 min after the initiation of the wave. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The detailed kinematics that we can do with these events allows us to study them far from the CME itself; as can be seen in Figure 3, the moment of reflection hapens some 45 min after the initiation of the wave. </div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=6575&oldid=prevHhudson: still drafting...2014-01-09T12:05:18Z<p>still drafting...</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Controversy has raged on and off regarding the relationships between the globalwaves and their causes (flare [blast wave]? or CME [bow wave]?).</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Controversy has raged on and off regarding the relationships between the globalwaves and their causes (flare [blast wave]? or CME [bow wave]?).</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>In this Nugget we do not discuss the exciters, but only the wave propagation.The particular events studied (see Ref. [1]) occurred on 27 January 2011:</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>In this Nugget we do not discuss the exciters, but only the wave propagation.The particular events studied (see Ref. [1]) occurred on 27 January 2011:</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>SOL2011-01-27T08:50 [<del class="diffchange diffchange-inline">B1</del>.<del class="diffchange diffchange-inline">1</del>], T12:<del class="diffchange diffchange-inline">18 </del>[<del class="diffchange diffchange-inline">B1</del>.<del class="diffchange diffchange-inline">9</del>] , and T20:03 (C1.5), all from the same active region.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>SOL2011-01-27T08:50 [<ins class="diffchange diffchange-inline">B6</ins>.<ins class="diffchange diffchange-inline">6</ins>], T12:<ins class="diffchange diffchange-inline">01 </ins>[<ins class="diffchange diffchange-inline">C1</ins>.<ins class="diffchange diffchange-inline">2</ins>] , and T20:03 (C1.5), all from the same active region.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is already interesting, because these are minor flares.The RHESSI [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is already interesting, because these are minor flares.The RHESSI [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>shows them, highlighting the 12:18 event because of its association with a radio [type II] event.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>shows them, highlighting the 12:18 event because of its association with a radio [type II] event.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This Nugget describes the subsequent propagation of the global waves and</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>reports <del class="diffchange diffchange-inline">a new </del>property: the apparently [specular reflection] of the <del class="diffchange diffchange-inline">wavesat </del>a distant magnetic domain wall.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>reports <ins class="diffchange diffchange-inline">the </ins>property: the apparently [specular reflection] of the <ins class="diffchange diffchange-inline">waves at </ins>a distant magnetic <ins class="diffchange diffchange-inline">feature, possibly the </ins>domain wall <ins class="diffchange diffchange-inline">of the south polar coronal hole</ins>.</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Observations ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Observations ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>We make use of the EUV images obtained by [STEREO-A] and by [PROBA2]; this </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>We make use of the EUV images obtained by [STEREO-A] and by [<ins class="diffchange diffchange-inline">http://proba2.oma.be/ </ins>PROBA2]; this </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>epoch put STEREO-A almost at [quadrature], i.e. with a nearly orthogonal view of the events.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>epoch put STEREO-A almost at [quadrature], i.e. with a nearly orthogonal view of the events.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events were at the extreme limb as viewed from near the Earth.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The events were at the extreme limb as viewed from near the Earth.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>structure, something only possible with STEREO.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>structure, something only possible with STEREO.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Figure 1 shows an overview of one of the events, T12:<del class="diffchange diffchange-inline">18</del>; this was the only one for which a radio type II burst was reported (but, as can be seen in the [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser] summary of the radio observations, all three events had intense type III bursts.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Figure 1 shows an overview of one of the events, T12:<ins class="diffchange diffchange-inline">01</ins>; this was the only one for which a radio type II burst was reported (but, as can be seen in the [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser] summary of the radio observations, all three events had intense type III bursts.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This may or may not be relevant!</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This may or may not be relevant!</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>These events are unusual in several ways.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>These events are unusual in several ways.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>'''First''', they arise from quite trivial flare events in NOAA 11149, just at the NW limb on the date of observation - a minor sunspot group.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>'''First''', they arise from quite trivial flare events in NOAA 11149, just at the NW limb on the date of observation - a minor sunspot group.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>'''Second''', there were three events in one day, quite <del class="diffchange diffchange-inline">unusual</del>; '''third''', they were closely [homologous], a striking property; fourth, the waves impinged almost at right angles to the magnetic boundary of the south polar coronal hole.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The detection of a type II burst from a [GOES] C-class event is noteworthy in its own right, and it is not surprising that only one of these three events could be detected in this manner.</ins></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Probably without these factors working so well together, we would not have been able to carry out such a detailed analysis of the wave reflection.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>'''Second''', there were three events in one day, quite <ins class="diffchange diffchange-inline">rare</ins>; '''third''', they were closely [homologous], a striking property; fourth, the waves impinged almost at right angles to the magnetic boundary of the south polar coronal hole.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Probably without these factors working so well together<ins class="diffchange diffchange-inline">, in an otherwise quite [http://www.solarmonitor.org/index.php?date=20110127&region=&indexnum=1 quiet corona</ins>, we would not have been able to carry out such a detailed analysis of the wave reflection<ins class="diffchange diffchange-inline">.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The stereoscopic view afforded by [http://proba2.oma.be/ PROBA2], from its low Earth orbit, allows us to study the reflection in the third dimension.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">Figure 2 shows this,</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[[File:217f2.png|800px|thumb|center|Fig. 2: </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">Stereoscopic views of two of the events, capturing the third dimension</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">]]</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">We learned from this stereoscopy that the primary wave appears most prominently at low altitudes, consistent with the idea that the expected vertical increase of Alfven speed should serve to refract the wave normal away from the vertical. </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">We also learned that the reflected wave emerged with a upwards tilt, i.e. more toward the vertical.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The reflection angle was of the order of 10<sup>o</sup>, consistent with the angle of incidence as expected from a specular reflection.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[[File:217f3.png|600px|thumb|center|Fig. 3: </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">Kinematics of the T12:01 event, showing the positions of the primary wave and of the reflected wave.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">]]</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The detailed kinematics that we can do with these events allows us to study them far from the CME itself; as can be seen in Figure 3, the moment of reflection hapens some 45 min after the initiation of the wave. </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">Assuming a vertical speed equal to the initial horizontal speed as observed, this would put the nose of the CME at a vertical distance of 1.9+-0.2 R<sub>Sun</sub>, and so we are observing a process in the distant flank of a bow wave, or simply a freely propagating disturbance, in the case of a blast wave.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">In the vicinity of the reflection, both incident and reflected waves have relatively low speeds.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">== Conclusions ==</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The refraction and reflection of global coronal waves is a necessary consequence of their characteristic description in the MHD framework, as note long ago in Uchida's original analysis. </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The events of 27 January 2011 that we've described in Ref. [1] provided the cleanest evidence yet that magnetic irregularities can result not only in refraction, as often pointed out, but in apparently exact specular reflection.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">One puzzle is that the surface of the domain boundary at the polar coronal hole should tilt away from the vertical as the field expands outwards, in a manner inconsistent with the observed angle of reflection.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">Another possibility is that the reflection involves the structure of the polar-crown filament cavity, as note in the [aurora polaris] described in Ref. [2] and elsewhere.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">This is a question that might be resolved by PFSS modeling, which for a quiet corona such as this one may be quite precise</ins>.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>* [1] [http://adsabs.harvard.edu/abs/2013SoPh..286..201K STEREO-A and PROBA2 Quadrature Observations of Reflections of Three EUV Waves from a Coronal Hole]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>* [1] [http://adsabs.harvard.edu/abs/2013SoPh..286..201K STEREO-A and PROBA2 Quadrature Observations of Reflections of Three EUV Waves from a Coronal Hole]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">* [2] [http://adsabs.harvard.edu/abs/1996ApJ...470..629H A Long-Duration Solar Flare with Mass Ejection and Global Consequences]</ins></div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[category: nugget]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[category: nugget]]</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=6574&oldid=prevHhudson: starting 2172014-01-09T11:09:24Z<p>starting 217</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We make use of the EUV images obtained by [STEREO-A] and by [PROBA2]; this </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We make use of the EUV images obtained by [STEREO-A] and by [PROBA2]; this </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>epoch put STEREO-A almost at [quadrature], i.e. with a nearly <del class="diffchange diffchange-inline">orthogonalview </del>of the events.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>epoch put STEREO-A almost at [quadrature], i.e. with a nearly <ins class="diffchange diffchange-inline">orthogonal view </ins>of the events<ins class="diffchange diffchange-inline">.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">The events were at the extreme limb as viewed from near the Earth</ins>.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Thus the analysis of the wave dynamics can delve into the three-dimensional</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>structure, something only possible with STEREO.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>structure, something only possible with STEREO.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Figure 1 shows an overview.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Figure 1 shows an overview <ins class="diffchange diffchange-inline">of one of the events, T12:18; this was the only one for which a radio type II burst was reported (but, as can be seen in the [http://sprg</ins>.<ins class="diffchange diffchange-inline">ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser] summary of the radio observations, all three events had intense type III bursts.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">This may or may not be relevant!</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:217f1.png|800px|thumb|center|Fig. 1: </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:217f1.png|800px|thumb|center|Fig. 1: </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Overview of <del class="diffchange diffchange-inline">the three </del>wave <del class="diffchange diffchange-inline">events</del>.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Overview of <ins class="diffchange diffchange-inline">Wave No. 2, as seen by STEREO-A. The black lines are </ins>wave <ins class="diffchange diffchange-inline">fronts from the disturbances emanating in the active region; the yellow lines show the reflections detected at the boundary of the south polar coronal hole. The other lines show meridians, propagation great circles, and circular fits to the boundary of the coronal hole</ins>. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div> </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">These events are unusual in several ways.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">'''First''', they arise from quite trivial flare events in NOAA 11149, just at the NW limb on the date of observation - a minor sunspot group.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">'''Second''', there were three events in one day, quite unusual; '''third''', they were closely [homologous], a striking property; fourth, the waves impinged almost at right angles to the magnetic boundary of the south polar coronal hole.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">Probably without these factors working so well together, we would not have been able to carry out such a detailed analysis of the wave reflection.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Reflection_of_Coronal_Global_Waves&diff=6573&oldid=prevHhudson: Created page with "{{Infobox Nugget |name = Nugget |title = Reflection of Coronal Global Waves |first_author = Ines Kienreich |second_author = Hugh Hudson |publish_date = January 13, 2014|previous_..."2014-01-09T10:50:39Z<p>Created page with "{{Infobox Nugget |name = Nugget |title = Reflection of Coronal Global Waves |first_author = Ines Kienreich |second_author = Hugh Hudson |publish_date = January 13, 2014|previous_..."</p>
<p><b>New page</b></p><div>{{Infobox Nugget<br />
|name = Nugget<br />
|title = Reflection of Coronal Global Waves<br />
|first_author = Ines Kienreich<br />
|second_author = Hugh Hudson<br />
|publish_date = January 13, 2014|previous_nugget = [[Flare Coronal Rain]]<br />
|next_nugget = TBD<br />
|number = 217<br />
}}<br />
<br />
== Introduction ==<br />
<br />
Flares and CMEs can excite large-scale waves in the corona, observable by many<br />
techniques with our excellent modern data.<br />
These global waves can in extreme cases produce the [chromospheric] signature<br />
that we call a [Moreton wave], but since Uchida's early interpretative workin terms of MHD wave propagation, we have understood the chromospheric wave<br />
to be a consequence of the global wave itself.<br />
Controversy has raged on and off regarding the relationships between the globalwaves and their causes (flare [blast wave]? or CME [bow wave]?).<br />
In this Nugget we do not discuss the exciters, but only the wave propagation.The particular events studied (see Ref. [1]) occurred on 27 January 2011:<br />
SOL2011-01-27T08:50 [B1.1], T12:18 [B1.9] , and T20:03 (C1.5), all from the same active region.<br />
This is already interesting, because these are minor flares.The RHESSI [http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+gbmo+rms4a&date=20110127&time=120124&bar=1 Browser]<br />
shows them, highlighting the 12:18 event because of its association with a radio [type II] event.<br />
<br />
This Nugget describes the subsequent propagation of the global waves and<br />
reports a new property: the apparently [specular reflection] of the wavesat a distant magnetic domain wall.<br />
<br />
== Observations ==<br />
<br />
We make use of the EUV images obtained by [STEREO-A] and by [PROBA2]; this <br />
epoch put STEREO-A almost at [quadrature], i.e. with a nearly orthogonalview of the events.<br />
Thus the analysis of the wave dynamics can delve into the three-dimensional<br />
structure, something only possible with STEREO.<br />
Figure 1 shows an overview.<br />
<br />
[[File:217f1.png|800px|thumb|center|Fig. 1: <br />
Overview of the three wave events.<br />
]]<br />
<br />
<br />
<br />
== References ==<br />
<br />
* [1] [http://adsabs.harvard.edu/abs/2013SoPh..286..201K STEREO-A and PROBA2 Quadrature Observations of Reflections of Three EUV Waves from a Coronal Hole]<br />
<br />
[[category: nugget]]</div>Hhudson