Japan Geoscience Union Meeting 2014

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Oral

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM36_28PM2] Physics and Chemistry in the Atmosphere and Ionosphere

Mon. Apr 28, 2014 4:15 PM - 6:00 PM 312 (3F)

Convener:*Yuichi Otsuka(Solar-Terrestrial Environment Laboratory, Nagoya University), Takuya Tsugawa(National Institute of Information and Communications Technology), Seiji Kawamura(National Institute of Information and Communications Technology), Chair:Mitsuru Matsumura(Center for Space Science and Radio Engineering, University of Electro-Communications), Tatsuhiro Yokoyama(National Institute of Information and Communications Technology)

5:15 PM - 5:30 PM

[PEM36-P22_PG] Horizontal shapes of mid-latitude sporadic-E observed with GPS-TEC

3-min talk in an oral session

*Jun MAEDA1, Kosuke HEKI1 (1.Graduate school of Science, Hokkaido University.)

Keywords:Sporadic-E, GPS, TEC

The horizontal shapes of sporadic-E (Es) have remained uncovered due to the lack of effective observation methods. We use a dense array of Global Positioning System (GPS) receivers in Japan to map horizontal shapes of mid-latitude sporadic-E layers and explore their diversity. The spatial and temporal resolutions of the GPS array are ~25 km (in horizontal) and 30 s, respectively, which is ideal for studying the horizontal shape and movement of sporadic-E. Sporadic-E can be identified as positive anomalies of total electron content (TEC) along the line of sight between a satellite and a ground-based GPS station.The results of GPS-TEC observation, i.e., mapping of positive TEC anomaly caused by mid-latitude sporadic E are presented in this presentation with a special emphasis on latitudinal and temporal variations of horizontal shapes of Es-layers. We analyzed ~100 Es events in 2010-2013 to examine the latitudinal dependence of Es frontal structures with three study areas at different latitudes near ionosondes, namely Sarobetsu (geographical latitude: 45.16 N), Kokubunji (35.71 N) and Yamagwa (31.20 N). As a result, strong Es shares the large-scale frontal structure as a common shape regardless of the occurrence latitude and time (e.g., morning, afternoon, and the evening). The horizontal structures of large-scale fronts are typically elongated in east-west (E-W) with the length and width of ~300 km and ~30 km, respectively. However, lengths vary from 30 to 300 km by occasion. The alignment of frontal structures prefers E-W, ENE-WSW and NE-SW alignment with some exception of NW-SE and NNW-SSE aligned structures. We will also discuss the possible mechanisms for formation, development, and movement of mid-latitude sporadic-E based on the results of our observations and proposed theories.