Daytime Medium Scale Traveling Ionospheric Disturbances (MSTIDS) Over the Andes Mountains at Equatorial and Low Magnetic Latitudes

• Published in: Journal of geophysical research. Space physics 2023-10, Vol.128 (10), p.n/a
• Main Authors: Figueiredo, C. A. O. B., Wrasse, C. M., Vadas, S., Takahashi, H., Otsuka, Y., Nyassor, P. K., Shiokawa, K., Paulino, I., Barros, D.
• Format: Article
• Language: English
• Subjects: Daytime; detrended TEC; Equatorial regions; Equinoxes; Geomagnetism; Gravity waves; Latitude; Mountains; Propagation; Solstices; Spring; Spring (season); Summer; the Andes Mountains; Traveling ionospheric disturbances; Winter
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2023JA031477

We analyze daytime quiet‐time MSTIDs between 2013 and 2015 at the geomagnetic equatorial and low latitude regions of the Chilean and Argentinian Andes using keograms of detrended total electron content (dTEC). The MSTIDs had a higher occurrence rate at geomagnetic equatorial latitudes in the June solstice (winter) and spring (SON). The propagation directions changed with the season: summer (DJF) [southeast, south, southwest, and west], winter (JJA) [north and northeast], and equinoxes [north, northeast, south, southwest, and west]. In addition, the MSTIDs at low latitudes observed between 8:00 and 12:00 UT occur more often during the December solstice and propagate northwestward and northeastward. After 12:00 UT, they are mostly observed in the equinoxes and June solstice. Their predominant propagation directions depend on the season: summer (all directions with a preference for northeastward), autumn (MAM) [north and northeast], winter (north and northeast), and spring (north, northeast, and southwest). The MSTID propagation direction at different latitudes was explained by the location of the possible sources. Besides, we calculated MSTIDs parameters at geomagnetic low latitudes over the Andes Mountains and compared them with those estimated at the geomagnetic equatorial latitudes. We found that the former is smaller on average than the latter. Also, our observations validate recent model results obtained during geomagnetically quiet‐time as well as daytime MSTIDs during winter over the south of South America. These results suggest that secondary or high‐order gravity waves (GWs) from orographic forcing are the most likely source of these MSTIDs. Key Points Quiet‐time daytime MSTIDs were observed at equatorial and low‐geomagnetic latitudes over the Chilean and Argentinian Andes Mountains MSTIDs observed during summer at equatorial latitudes are most likely generated by higher‐order gravity waves from the Amazon region Equatorial and low‐geomagnetic latitude wintertime MSTIDs over the Andes may be secondary or higher‐order gravity waves