{"@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/1361699994714922880.json","@type":"Article","productIdentifier":[{"identifier":{"@type":"DOI","@value":"10.1029/2007ja012809"}},{"identifier":{"@type":"URI","@value":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2007JA012809"}},{"identifier":{"@type":"URI","@value":"https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2007JA012809"}}],"dc:title":[{"@value":"On monthly/seasonal/longitudinal variations of equatorial irregularity occurrences and their relationship with the postsunset vertical drift velocities"}],"description":[{"type":"abstract","notation":[{"@value":"<jats:p>Monthly variation of global equatorial density irregularity distribution has been obtained with the data taken by ROCSAT‐1 at the 600 km topside ionosphere from March 1999 to June 2004 during high to moderate solar activity years. This global distribution of monthly irregularity occurrence rate not only provides the best spatial/temporal distribution in existence so far but also serves to fill the gap of irregularity distribution missing over some eastern Pacific region where no ground observation is available. The 5 1/2‐year result of the monthly occurrence pattern indicates a smooth variation across the longitudes contrary to some beliefs that a drastic change in irregularity occurrence pattern has occurred across the eastern Pacific longitudes. Excellent agreement is noted for the current results with Aarons' (1993) conjectured sketch of the global scintillation distribution. Furthermore, the seasonal/longitudinal (s/l) variations of quiet time postsunset vertical drift velocities are found to track closely with the s/l variations of irregularity occurrences. Linear regression analysis between the vertical drift velocity and the irregularity occurrence rate indicates that the vertical drift velocities at three different longitude zones of magnetic declination have good correlations with the irregularity occurrences for all seasons. This implies that the averaged postsunset vertical drift velocity is a good indicator for the occurrences of equatorial density irregularities in a longitude region of similar magnetic declination. The smooth variation of monthly/seasonal/longitudinal distributions of the vertical drift velocities that results in the smooth variation of topside density irregularity occurrences implies that the global occurrence pattern of either distribution is controlled by the smooth global variation of the postsunset ionospheric condition, related to the magnetic declination effect and the seasonal variation of the ionospheric density level at the dip equator located with respect to the geographic equator. There seems little need to include the global distribution of instability perturbation seeds from atmospheric disturbances to complete the global distribution of topside irregularity occurrences.</jats:p>"}]}],"creator":[{"@id":"https://cir.nii.ac.jp/crid/1380579818750485760","@type":"Researcher","foaf:name":[{"@value":"S.‐Y. Su"}],"jpcoar:affiliationName":[{"@value":"Institute of Space Science and Center for Space and Remote Sensing Research National Central University  Chung‐Li Taiwan"}]},{"@id":"https://cir.nii.ac.jp/crid/1381699994714922880","@type":"Researcher","foaf:name":[{"@value":"C. K. Chao"}],"jpcoar:affiliationName":[{"@value":"Institute of Space Science National Central University  Chung‐Li Taiwan"}]},{"@id":"https://cir.nii.ac.jp/crid/1381699994714922881","@type":"Researcher","foaf:name":[{"@value":"C. H. Liu"}],"jpcoar:affiliationName":[{"@value":"Academia Sinica  Taipei Taiwan"}]}],"publication":{"publicationIdentifier":[{"@type":"PISSN","@value":"01480227"}],"prism:publicationName":[{"@value":"Journal of Geophysical Research: Space Physics"}],"dc:publisher":[{"@value":"American Geophysical Union (AGU)"}],"prism:publicationDate":"2008-05","prism:volume":"113","prism:number":"A5","prism:startingPage":"A05307"},"reviewed":"false","dc:rights":["http://onlinelibrary.wiley.com/termsAndConditions#vor"],"url":[{"@id":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2007JA012809"},{"@id":"https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2007JA012809"}],"createdAt":"2008-05-15","modifiedAt":"2023-10-31","relatedProduct":[{"@id":"https://cir.nii.ac.jp/crid/1050002213761756928","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@language":"en","@value":"Observation of seasonal asymmetry in the range spread F occurrence at different longitudes during low and moderate solar activity"}]},{"@id":"https://cir.nii.ac.jp/crid/1360002215432406400","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Low and Midlatitude Ionospheric Plasma Density Irregularities and Their Effects on Geomagnetic Field"}]},{"@id":"https://cir.nii.ac.jp/crid/1360009142833000320","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Ionospheric <i>F</i> Layer Scintillation Weakening as Observed by COSMIC/FORMOSAT‐3 During the Major Sudden Stratospheric Warming in January 2013"}]},{"@id":"https://cir.nii.ac.jp/crid/1360017282443420928","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"On the Generation of an Unseasonal EPB Over South East Asia"}]},{"@id":"https://cir.nii.ac.jp/crid/1360021389806439808","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Assessing the potential of ionosonde for forecasting post-sunset equatorial spread F: an observational experiment in Southeast Asia"}]},{"@id":"https://cir.nii.ac.jp/crid/1360306904387830656","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Was the Unseasonal Development of Post‐Sunset Equatorial Plasma Bubbles in Southeast Asia Driven by Quasi‐2‐Day Planetary Waves?"}]},{"@id":"https://cir.nii.ac.jp/crid/1360567180128575232","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Longitudinal characteristics of spread <i>F</i> backscatter plumes observed with the EAR and Sanya VHF radar in Southeast Asia"}]},{"@id":"https://cir.nii.ac.jp/crid/1360580232393507328","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Effect of the seed perturbation amplitude on the equatorial spread F initiation during solar minimum"}]},{"@id":"https://cir.nii.ac.jp/crid/1360869855560216704","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Regional Ionospheric Super Bubble Induced by Significant Upward Plasma Drift During the 1 December 2023 Geomagnetic Storm"}]},{"@id":"https://cir.nii.ac.jp/crid/2050588892082797824","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Post-sunset rise of equatorial F layer-or upwelling growth？"}]},{"@id":"https://cir.nii.ac.jp/crid/2051151842031800576","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Unseasonal development of post-sunset F-region irregularities over Southeast Asia on 28 July 2014 : 1. 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