Statistical Study of Medium-Scale Traveling Ionospheric Disturbances Observed with a GPS Receiver Network in Japan
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Using densely spaced GPS receivers in Japan, we investigated two-dimensional maps of total electron content (TEC) perturbations with a spatial resolution of 0.15×0.15° in longitude and latitude to reveal the statistical characteristics of medium-scale traveling ionospheric disturbances (MSTIDs). We found that MSTIDs can be categorized into three groups: daytime, nighttime, and dawn and dusk MSTIDs. Daytime MSTIDs frequently occur in winter and tend to propagate southeastward. We speculate that daytime MSTIDs are caused by atmospheric gravity waves in the thermosphere. Nighttime MSTIDs frequently occur in summer and propagate southwestward. This propagation direction supports the notion that polarization electric fields could play an important role in generating nighttime MSTIDs. Dawn and dusk MSTIDs frequently occur in summer and propagate eastward and north-northwestward, respectively.
KeywordsGlobal Position System Gravity Wave Total Electron Content Global Position System Receiver Neutral Wind
GEONET GPS data were provided by the Geographical Survey Institute of Japan.
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