On a summer maximum in the occurrence frequency of 150 km (<i>F</i><sub>1</sub>) radar echoes over Pohnpei
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- Roland T. Tsunoda
- Center for Geospace Studies SRI International Menlo Park California USA
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- Warner L. Ecklund
- Aeronomy Laboratory, National Oceanic and Atmospheric Administration Boulder Colorado USA
書誌事項
- 公開日
- 2004-03
- 権利情報
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- http://onlinelibrary.wiley.com/termsAndConditions#vor
- DOI
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- 10.1029/2003gl018704
- 公開者
- American Geophysical Union (AGU)
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説明
<jats:p>Using three and a half years of 50 MHz radar data collected from Pohnpei, Federated States of Micronesia (6.96°N, 158.19°E geographic, 0.3° magnetic dip latitude), we show for the first time that the occurrence frequency of 150 km (or <jats:italic>F</jats:italic><jats:sub>1</jats:sub>) echoes has a broad but conspicuous maximum during northern summer in this longitude sector with minimal activity in other months. Given a seasonal similarity to sporadic <jats:italic>E</jats:italic> (<jats:italic>E</jats:italic><jats:sub><jats:italic>s</jats:italic></jats:sub>), we suggest that an <jats:italic>E</jats:italic><jats:sub><jats:italic>s</jats:italic></jats:sub>‐layer instability [<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#grl17658-bib-0005"><jats:italic>Cosgrove and Tsunoda</jats:italic>, 2002</jats:ext-link>] generates a polarization electric field (<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/grl17658-math-0001.gif" xlink:title="equation image"/>), which maps along geomagnetic field lines to the <jats:italic>F</jats:italic><jats:sub>1</jats:sub> region. There, <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/grl17658-math-0001.gif" xlink:title="equation image"/> forms thin plasma sheets that provide gradients to excite 3‐m‐scale plasma waves via an interchange process.</jats:p>
収録刊行物
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- Geophysical Research Letters
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Geophysical Research Letters 31 (6), 810-, 2004-03
American Geophysical Union (AGU)
