Morphology and dynamics of daytime mid-latitude sporadic-E patches revealed by GPS total electron content observations in Japan

Morphological characteristics of daytime mid-latitude sporadic-E (Es) patches are studied by two-dimensional total electron content (TEC) maps drawn using the Japanese dense network of Global Positioning System (GPS) receivers. By analyzing over 70 cases, we found that their horizontal shapes are characterized by frontal structure typically elongated in east-west by ~100 km. They are observed to migrate mainly northward in the morning and southward in the afternoon with speeds of 30–100 m/s. This may reflect the velocities of neutral winds controlled by the atmospheric tides. Such frontal structures are often found to include smaller scale structures.