{"id":1461,"date":"2021-05-13T14:12:14","date_gmt":"2021-05-13T14:12:14","guid":{"rendered":"https:\/\/aurorasaurudev.wpengine.com\/?p=1461"},"modified":"2023-12-26T21:55:43","modified_gmt":"2023-12-26T21:55:43","slug":"the-discovery-of-the-auroral-dunes-how-one-thing-led-to-another","status":"publish","type":"post","link":"https:\/\/blog.aurorasaurus.org\/?p=1461","title":{"rendered":"The discovery of the auroral dunes: How one thing led to another"},"content":{"rendered":"<p><b><\/b><i><span style=\"font-weight: 400;\">Guest blog post. Dr. Minna Palmroth is Professor of Computational Space Physics and the Director of the Finnish Centre of Excellence in Research of Sustainable Space at the University of Helsinki, Finland. <\/span><\/i><i><span style=\"font-weight: 400;\">On June 15, 2020, Dr. Palmroth gave a presentation to the Aurorasaurus Ambassadors about the discovery of dune aurora, viewable <\/span><\/i><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/youtu.be\/e5A8kqd0HmY\"><i><span style=\"font-weight: 400;\">on our YouTube channel<\/span><\/i><\/a><i><span style=\"font-weight: 400;\">.\u00a0<\/span><\/i><\/p>\n<hr \/>\n<p><b>The dune aurora may give new information from one of the last frontiers on Earth, a curious layer in the upper atmosphere where space touches the atmosphere. This place is so hard to measure that it is sometimes called the <\/b><b><i>ignorosphere<\/i><\/b><b>.<\/b><\/p>\n<p><center><iframe loading=\"lazy\" title=\"YouTube video player\" src=\"https:\/\/www.youtube.com\/embed\/F6xM-XY6NYg\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><i><br \/>\n&#8220;A time lapse video recorded by a Scottish aurora borealis hobbyist Grame Whipps was used to determine the speed of the phenomenon at over 200 m\/s.&#8221; (<a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/www2.helsinki.fi\/en\/news\/science-news\/confirmation-of-an-auroral-phenomenon-discovered-by-finns\">Pellinen, 2021<\/a>).<\/i><\/center><center><\/center>&nbsp;<\/p>\n<p><span style=\"font-weight: 400;\">On a cloudy and dark November morning in 2015 I received a very polite email \u2013 \u201c<\/span><i><span style=\"font-weight: 400;\">could the good professor join our auroral enthusiast <\/span><\/i><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/www.facebook.com\/groups\/revontulikyttaajat\/\"><i><span style=\"font-weight: 400;\">Facebook group<\/span><\/i><\/a><i><span style=\"font-weight: 400;\"> and explain the physics of aurora for us \u2026\u201d<\/span><\/i><span style=\"font-weight: 400;\">.\u00a0 This will cheer me up, I thought, and joined the group. Over the years I became the group\u2019s staff scientist: explaining things, pointing toward data and indices, interpreting pictures. At some point I noticed that while the number of members grows (now over 17,000), I\u2019m always explaining the same things. This led to the second step: the book project.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">I listed the auroral forms known in science: arc, corona, omega band, diffuse aurora, etc, and asked the people in the group to find examples of the different forms. I contacted two friends, the legendary auroral photographer <\/span><b>Jouni Jussila<\/b><span style=\"font-weight: 400;\"> whom I knew already from grad school, and the legendary author <\/span><b>Markus Hotakainen<\/b><span style=\"font-weight: 400;\">. They were immediately inspired. We wrote basically a birdwatching <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/kauppa.intokustannus.fi\/kirja\/revontulibongarin-opas\/\"><i><span style=\"font-weight: 400;\">guidebook<\/span><\/i><\/a><span style=\"font-weight: 400;\">, but instead of birds we showed examples of the auroral forms, explained their background, and even added a <\/span><span style=\"font-weight: 400;\">star classification showing how rare the form is.<\/span><span style=\"font-weight: 400;\"> Now, I thought, the most frequently asked questions were explained!<\/span><\/p>\n<p><span style=\"font-weight: 400;\">But no \u2013 that led to the next step: While choosing example pictures for the guidebook, we engaged some of the most active Facebook group members to help. One of them, <\/span><b>Matti Helin<\/b><span style=\"font-weight: 400;\"> asked \u201c<\/span><i><span style=\"font-weight: 400;\">\u2026 but what are these stripes\u2026<\/span><\/i><span style=\"font-weight: 400;\">\u201d and showed us a picture with regular, horizontal waves in the diffuse green aurora. I had never seen anything like them, and we left the stripes out from the book. The book got published on 5 Oct 2018, and in the aftermath of the publication party, on 7 Oct 2018, while messaging with the picture selection group, Matti Helin suddenly shouted a message: \u201cTHE STRIPES ARE ON THE SKY!\u201d<\/span><\/p>\n<figure id=\"attachment_1467\" aria-describedby=\"caption-attachment-1467\" style=\"width: 522px\" class=\"wp-caption aligncenter\"><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/blog.aurorasaurus.org\/wp-content\/uploads\/2021\/05\/aga220017-fig-0001-m.jpeg\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-1467\" src=\"https:\/\/blog.aurorasaurus.org\/wp-content\/uploads\/2021\/05\/aga220017-fig-0001-m.jpeg\" alt=\"Two photos show wavelike auroral &quot;dunes&quot;\" width=\"522\" height=\"515\" \/><\/a><figcaption id=\"caption-attachment-1467\" class=\"wp-caption-text\">(a) Auroral dunes captured on 7 October 2018, at 17:40.59 UT in Laitila (see location in Figure 4b). The stars in the background indicate that the field of view is toward the northwest. The dunes (marked by magenta circles and numbers, which refer to section 2) extend equatorward from the discrete bright arc in the north. The local magnetic field direction is shown by the auroral pillars, the almost vertical purple structures. (b) Simultaneous picture of the dunes in Ruovesi, 172 km northeast from Laitila. The background star positions indicate that the field of view is roughly toward the west. (Palmroth et al., 2020).<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400;\">The other aurora chasers immediately ran out to take pictures and I tried to coordinate things from my couch. Long story short, we got two simultaneous pictures from two different places. A postdoc from my group, <\/span><b>Maxime Grandin<\/b><span style=\"font-weight: 400;\">, developed a clever trigonometric method to use the pictures as data, and we got an altitude and a wavelength to the structures. At some point one of the enthusiasts, <\/span><b>Pirjo Koski<\/b><span style=\"font-weight: 400;\">, came up with a name: <\/span><i><span style=\"font-weight: 400;\">dunes<\/span><\/i><span style=\"font-weight: 400;\">, and that stuck.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Writing the dune discovery paper was like a rollercoaster of feelings, possibly analogous to an actor who repeatedly succeeds and fails on stage in front of the audience, although in our case the citizens were actively involved in the play. Finally we came to the conclusion that the dunes are a manifestation of a relatively rare type of atmospheric wave called a <\/span><i><span style=\"font-weight: 400;\">mesospheric bore<\/span><\/i><span style=\"font-weight: 400;\">. We suggested that the brighter stripes in the aurora would result from a larger density of excitation targets in atmospheric oxygen, while the dimmer parts in between bright stripes would indicate lack of emission from the atmospheric wave trough.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">One of the proudest moments of the entire process was when we realized that a brand-new, high-impact journal, American Geophysical Union\u2019s counterpart to <\/span><i><span style=\"font-weight: 400;\">Nature,<\/span><\/i><span style=\"font-weight: 400;\"> called <\/span><i><span style=\"font-weight: 400;\">AGU Advances,<\/span><\/i><span style=\"font-weight: 400;\"> published our <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/agupubs.onlinelibrary.wiley.com\/doi\/10.1029\/2019AV000133\"><span style=\"font-weight: 400;\">article<\/span><\/a><span style=\"font-weight: 400;\"> in its first volume, issue one, pages 1-12, and on the cover page. In this article we speculated that the atmosphere forms a horizontal waveguide for the bore to travel, and the aurora illuminates the wave crests. Since we didn\u2019t have data on the location of the dunes, we couldn\u2019t say for sure. In any case the discovery \u201cbombed the bank\u201d as we say in Finland; the <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/www2.helsinki.fi\/en\/news\/science-news\/citizen-science-discovers-a-new-form-of-the-northern-lights\"><span style=\"font-weight: 400;\">press release<\/span><\/a><span style=\"font-weight: 400;\"> reached over 3 billion people on all continents, and I spent two weeks commenting on the discovery nonstop for all kinds of journalists.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Now we can continue the story, because on <\/span><b>May 4, 2021<\/b><span style=\"font-weight: 400;\">, AGU Advances published <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/doi.org\/10.1029\/2020AV000338\"><i><span style=\"font-weight: 400;\">our second dune paper<\/span><\/i><\/a><span style=\"font-weight: 400;\">! This is a paper by <\/span><b>Maxime Grandin<\/b><span style=\"font-weight: 400;\"> \u2013 this time featuring dunes from Finland to Scotland \u2013 and including <\/span><i><span style=\"font-weight: 400;\">in situ<\/span><\/i><span style=\"font-weight: 400;\"> measurements linking the waveguide with the dunes. However, we still didn\u2019t observe the bore itself, not because it was not potentially there, but because density measurements were not available, nor were airglow observations where bore signatures are typically present. So the story hopefully continues with new events.<\/span><\/p>\n<figure id=\"attachment_1463\" aria-describedby=\"caption-attachment-1463\" style=\"width: 527px\" class=\"wp-caption aligncenter\"><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/blog.aurorasaurus.org\/wp-content\/uploads\/2021\/05\/aga220075-fig-0001-m.jpeg\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-1463\" src=\"https:\/\/blog.aurorasaurus.org\/wp-content\/uploads\/2021\/05\/aga220075-fig-0001-m.jpeg\" alt=\"A collage of 5 images show dune aurora\" width=\"527\" height=\"602\" \/><\/a><figcaption id=\"caption-attachment-1463\" class=\"wp-caption-text\">Selected pictures of the dune aurora by Citizen Scientists during the 20 January 2016 event. The pictures were taken from (a) Aura, Finland, at 17:23 UT, (b) Engerdal, Norway, at 20:13 UT, (c) Karm\u00f8y, Norway, around 20:30 UT, (d) the Isle of Mull, Scotland, at 20:57 UT, (e) Lendalfoot, Scotland, at 21:15 UT, and (f) Rattray, Scotland, at 21:15 UT. (g) (Grandin et al., 2021)<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400;\">If you have seen the dunes, we would love to hear about it, because new observations would give us more opportunities to understand this incredibly fascinating phenomenon. The dune observations are important because they may give a new glance from the <\/span><i><span style=\"font-weight: 400;\">ignorosphere<\/span><\/i><span style=\"font-weight: 400;\">, the last frontier of unknown places on Earth where space touches the atmosphere. This place is extremely hard to measure, but with dune pictures we can explore it!<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Minna Palmroth<\/span><\/p>\n<p>University of Helsinki press releases:<\/p>\n<p><span style=\"font-weight: 400;\">Palmroth et al 2020: <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/www2.helsinki.fi\/en\/news\/science-news\/citizen-science-discovers-a-new-form-of-the-northern-lights\"><span style=\"font-weight: 400;\">https:\/\/www2.helsinki.fi\/en\/news\/science-news\/citizen-science-discovers-a-new-form-of-the-northern-lights<\/span><\/a><\/p>\n<p><span style=\"font-weight: 400;\">Grandin et al 2021: <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/www2.helsinki.fi\/en\/news\/science-news\/confirmation-of-an-auroral-phenomenon-discovered-by-finns\"><span style=\"font-weight: 400;\">https:\/\/www2.helsinki.fi\/en\/news\/science-news\/confirmation-of-an-auroral-phenomenon-discovered-by-finns<\/span><\/a><\/p>\n<p><span style=\"font-weight: 400;\">Pictures and timelapse in AGU press release: <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/news.agu.org\/press-release\/citizen-scientists-discover-new-type-of-aurora-named-the-dunes-video-available\/\"><span style=\"font-weight: 400;\">https:\/\/news.agu.org\/press-release\/citizen-scientists-discover-new-type-of-aurora-named-the-dunes-video-available\/<\/span><\/a><\/p>\n<p><span style=\"font-weight: 400;\">Editor&#8217;s Highlight on EOS: <\/span><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/eos.org\/editor-highlights\/dune-aurora-explained-by-satellite-ground-studies\"><span style=\"font-weight: 400;\">https:\/\/eos.org\/editor-highlights\/dune-aurora-explained-by-satellite-ground-studies<\/span><\/a><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\n<p>Taivaanvahti citizen science observation system\u00a0<a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/www.taivaanvahti.fi\/\">https:\/\/www.taivaanvahti.fi\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Guest blog post. Dr. Minna Palmroth is Professor of Computational Space Physics and the Director of the Finnish Centre of Excellence in Research of Sustainable Space at the University of Helsinki, Finland. On June 15, 2020, Dr. Palmroth gave a presentation to the Aurorasaurus Ambassadors about the discovery of dune aurora, viewable on our YouTube&hellip;&nbsp;<a href=\"https:\/\/blog.aurorasaurus.org\/?p=1461\" rel=\"bookmark\">Read More &raquo;<span class=\"screen-reader-text\">The discovery of the auroral dunes: How one thing led to another<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":1467,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"rop_custom_images_group":[],"rop_custom_messages_group":[],"rop_publish_now":"initial","rop_publish_now_accounts":[],"rop_publish_now_history":[],"rop_publish_now_status":"pending","neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"off","neve_meta_content_width":70,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[24,6,17,12],"tags":[20,21,23],"class_list":["post-1461","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-citizen-science","category-large-aurora-events","category-other-resources-for-aurora-hunters","category-understanding-the-aurora","tag-auroras","tag-citizen-science","tag-northern-lights"],"_links":{"self":[{"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=\/wp\/v2\/posts\/1461","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1461"}],"version-history":[{"count":0,"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=\/wp\/v2\/posts\/1461\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=\/wp\/v2\/media\/1467"}],"wp:attachment":[{"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1461"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1461"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.aurorasaurus.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1461"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}