Large‐scale traveling ionospheric disturbances observed by GPS dTEC maps over North and South America on Saint Patrick's Day storm in 2015

• Published in: Journal of geophysical research. Space physics 2017-04, Vol.122 (4), p.4755-4763
• Main Authors: Figueiredo, C. A. O. B., Wrasse, C. M., Takahashi, H., Otsuka, Y., Shiokawa, K., Barros, D.
• Format: Article
• Language: English
• Subjects: Asymmetry; Equator; Equatorial regions; Geomagnetic storms; Geophysics; Ionosphere; Latitude; LSTID; magnetic storm; Magnetic storms; Northern Hemisphere; Phase velocity; Plasma; Polar environments; Polar regions; Propagation; Southern Hemisphere; Storms; Traveling ionospheric disturbances; Wave propagation; Wavelengths; waves
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2016JA023417

Large‐scale traveling ionospheric disturbances (LSTIDs) were detected in both Northern and Southern Hemispheres over American sector during the geomagnetic storm on 17–18 March 2015, also known as the Saint Patrick's Day storm. Detrended total electronic content (dTEC) maps were made using dense GNSS network receiver data. The retrieved LSTIDs showed wavelengths of 1000 to 2000 km, phase velocity of ~300–1000 m/s, and period of ~30–50 min. Among them, three couples of LSTIDs were observed propagating from the polar regions to low latitudes. Two wave events observed in daytime showed the propagation direction of southwest in the Northern Hemisphere and northeast in the Southern Hemisphere, which means an asymmetric propagation against the geographic equator. The other wave event observed during the evening hour showed symmetric propagation direction, i.e., southwest in the Northern Hemisphere and northwest in the Southern Hemisphere, whereas their wavelength and phase velocity are significantly different between NH and SH. These observations indicate that the two groups of LSTID have different propagation conditions from polar to low‐latitude regions. The observed asymmetric/symmetric propagation forms suggest asymmetric/symmetric auroral current activity between the northern and southern polar regions. Key Points LSTIDs were detected in both Northern and Southern Hemispheres over the American sector during the geomagnetic storm on 17–18 March 2015 LSTIDs in South and North Hemispheres with different propagation direction during the main phase of magnetic storm The observed propagation forms suggest asymmetric/symmetric auroral current activity between the northern and southern polar regions