6:15 PM - 7:30 PM
[PEM36-P22] Horizontal shapes of mid-latitude sporadic-E observed with GPS-TEC
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.