{"@context":{"@vocab":"https://cir.nii.ac.jp/schema/1.0/","rdfs":"http://www.w3.org/2000/01/rdf-schema#","dc":"http://purl.org/dc/elements/1.1/","dcterms":"http://purl.org/dc/terms/","foaf":"http://xmlns.com/foaf/0.1/","prism":"http://prismstandard.org/namespaces/basic/2.0/","cinii":"http://ci.nii.ac.jp/ns/1.0/","datacite":"https://schema.datacite.org/meta/kernel-4/","ndl":"http://ndl.go.jp/dcndl/terms/","jpcoar":"https://github.com/JPCOAR/schema/blob/master/2.0/"},"@id":"https://cir.nii.ac.jp/crid/1361981471230654592.json","@type":"Article","productIdentifier":[{"identifier":{"@type":"DOI","@value":"10.1029/1999ja900416"}},{"identifier":{"@type":"URI","@value":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F1999JA900416"}},{"identifier":{"@type":"URI","@value":"https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999JA900416"}}],"dc:title":[{"@value":"Evaluation of low‐latitude Pi2 pulsations as indicators of substorm onset using Polar ultraviolet imagery"}],"description":[{"type":"abstract","notation":[{"@value":"<jats:p>Impulsive Pi2 pulsations have long been recognized as one of the key signatures of magnetic activity during substorm periods due to their wide observable range both in latitudes and longitudes. It is well documented that there is usually more than one Pi2 wave burst associated with a substorm and only one of them corresponds to the onset of the substorm. This observational fact poses obstacles to determining substorm onsets with Pi2 signals. Although the Pi2 have become one of the most popular indicators for substorm onsets, the reliability of using the Pi2 in this fashion has not been seriously investigated. In this paper we address this question with a statistical approach by using ∼650 auroral substorm onsets identified with Polar ultraviolet images for a time interval from April 1996 to May 1997. A comparison of the low‐latitude Pi2 pulsation onsets from Kakioka (<jats:italic>L</jats:italic> = 1.07) with the auroral breakups indicates that identifying substorm onset with the Pi2 alone is often ambiguous. Of a total of 119 isolated (defined as ∼10 min of quiet time preceding the onset) Pi2 bursts seen within ∼10 min from a magnetic positive bay, there were 65 events (∼55%) taking place within 3 min from breakups and 34 events (29%) indicating no sign of an auroral breakup within 10 min of the Pi2 burst. This result suggests that Pi2 may not be as a good indicator of the substorm onset as it was thought to be. Interestingly, it is always possible to associate Pi2 pulsations with some forms of auroral intensification. When compared to auroral breakups, Pi2 onsets are subject to a small delay of 1 – 3 min, with a peak around l min. Delays of Pi2 onsets are revealed to be a function of location relative to auroral breakup. This dependence is found to be consistent with the time of flight for a fast‐mode wave, in a plasmapause cavity mode model, propagating in the magnetosphere.</jats:p>"}]}],"creator":[{"@id":"https://cir.nii.ac.jp/crid/1380285532848685709","@type":"Researcher","foaf:name":[{"@value":"K. Liou"}]},{"@id":"https://cir.nii.ac.jp/crid/1380298342457308289","@type":"Researcher","foaf:name":[{"@value":"C.‐I. Meng"}]},{"@id":"https://cir.nii.ac.jp/crid/1381981471230654597","@type":"Researcher","foaf:name":[{"@value":"P. T. Newell"}]},{"@id":"https://cir.nii.ac.jp/crid/1381981471230654594","@type":"Researcher","foaf:name":[{"@value":"K. Takahashi"}]},{"@id":"https://cir.nii.ac.jp/crid/1380298342457308288","@type":"Researcher","foaf:name":[{"@value":"S.‐I. Ohtani"}]},{"@id":"https://cir.nii.ac.jp/crid/1381981471230654464","@type":"Researcher","foaf:name":[{"@value":"A. T. Y. Lui"}]},{"@id":"https://cir.nii.ac.jp/crid/1381981471230654465","@type":"Researcher","foaf:name":[{"@value":"M. Brittnacher"}]},{"@id":"https://cir.nii.ac.jp/crid/1381981471230654592","@type":"Researcher","foaf:name":[{"@value":"G. Parks"}]}],"publication":{"publicationIdentifier":[{"@type":"PISSN","@value":"01480227"}],"prism:publicationName":[{"@value":"Journal of Geophysical Research: Space Physics"}],"dc:publisher":[{"@value":"American Geophysical Union (AGU)"}],"prism:publicationDate":"2000-02","prism:volume":"105","prism:number":"A2","prism:startingPage":"2495","prism:endingPage":"2505"},"reviewed":"false","dc:rights":["http://onlinelibrary.wiley.com/termsAndConditions#vor"],"url":[{"@id":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F1999JA900416"},{"@id":"https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999JA900416"}],"createdAt":"2002-09-17","modifiedAt":"2023-09-23","relatedProduct":[{"@id":"https://cir.nii.ac.jp/crid/1050001338207801472","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@language":"en","@value":"Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images"}]},{"@id":"https://cir.nii.ac.jp/crid/1050008909147858560","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@language":"en","@value":"Multi‐Event Analysis of Plasma and Field Variations in Source of Stable Auroral Red (SAR) Arcs in Inner Magnetosphere During Non‐Storm‐Time Substorms"}]},{"@id":"https://cir.nii.ac.jp/crid/1360283691683877888","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Longitudinal association between magnetotail reconnection and auroral breakup based on Geotail and Polar observations"}]},{"@id":"https://cir.nii.ac.jp/crid/1360283691686385536","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"A statistical study of energy release and transport midway between the magnetic reconnection and initial dipolarization regions in the near‐Earth magnetotail associated with substorm expansion onsets"}]},{"@id":"https://cir.nii.ac.jp/crid/1360567179754091904","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Substorm onset process: Ignition of auroral acceleration and related substorm phases"}]},{"@id":"https://cir.nii.ac.jp/crid/1360567180787592704","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"A Statistical Study of Pressure Changes in the Near-Earth Magnetotail Associated with Substorm Expansion Onsets"}]},{"@id":"https://cir.nii.ac.jp/crid/1360848658217042432","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Pressure changes associated with substorm depolarization in the near‐Earth plasma sheet"}]},{"@id":"https://cir.nii.ac.jp/crid/1360848658217172352","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"AKR modulation and global Pi2 oscillation"}]},{"@id":"https://cir.nii.ac.jp/crid/1390001206512844288","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@language":"en","@value":"Longitudinal dependence of characteristics of low-latitude Pi2 pulsations observed at Kakioka and Hermanus"}]},{"@id":"https://cir.nii.ac.jp/crid/1390001206513255808","@type":"Article","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@language":"en","@value":"Characteristics of Pi 2 magnetic pulsations observed at the CPMN stations"},{"@value":"Characteristics of Pi 2 magnetic pulsations observed at the CPMN stations: A review of the STEP results"}]}],"dataSourceIdentifier":[{"@type":"CROSSREF","@value":"10.1029/1999ja900416"},{"@type":"CROSSREF","@value":"10.1029/2008ja013127_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1029/2012ja017925_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1186/s40623-018-0843-3_references_DOI_CMoX3Wal6aEuJqGjdfPLswpJogL"},{"@type":"CROSSREF","@value":"10.1002/2013ja019442_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1007/978-94-007-0501-2_7_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1029/2020ja029081_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1186/bf03351695_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1186/bf03351981_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1029/2010ja015608_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"},{"@type":"CROSSREF","@value":"10.1029/2010ja016042_references_DOI_99aCsv1fMsDxiycoLt5wDHnObm4"}]}