SA013-03
Traveling Ionospheric Disturbance Tracking through Doppler-Shifted AM Radio Transmissions

Wednesday, 9 December 2020: 20:38
Virtual
Claire Trop1, James W Labelle2, David McGaw1, Phillip Erickson3, Shunrong Zhang4 and Terrence Kovacs5, (1)Dartmouth College, Hanover, NH, United States, (2)Dartmouth College, Department of Physics & Astronomy, Hanover, NH, United States, (3)MIT Haystack Observatory, Westford, United States, (4)MIT Haystack Observatory, Westford, MA, United States, (5)Dartmouth College, Department of Physics and Astronomy, Hanover, United States
Recorded Presentation
Abstract:
A comprehensive understanding of the ionosphere is critical for many technologies, particularly those that rely on the propagation of radio waves. This study shows that traveling ionospheric disturbances (TIDs) can be tracked and analyzed using clear channel AM radio transmissions and a set of geographically distributed receivers. Early attempts by our research group to track TIDs by AM radio signals reflected from the F region of the ionosphere generated results in conflict with those derived from GPS/TEC mapping methods [Chilcote et al., 2015].This study seeks to resolve those conflicts with a more sophisticated array of receivers spread throughout the northeastern United States. Specifically, the receivers form a ring around an 810 kHz AM radio station in Schenectady, New York. A minimum of four receivers were operational from 3/19/20 to 7/29/20 and Doppler-shifted signals, attributed to TID events, have been consistently visible across several radio channels with frequencies between 800 to 1600kHz. Two exceptional events, 5/5/20 and 7/13/20, with five and six receivers operational respectively, were selected for specific analysis. The initial analysis suggests that the event in May has a phase velocity of .68 km/s and a wavelength of 1316 km. The disturbance appears to propagate from the northwest to the southeast. The event in July has a phase velocity of .61 km/s, a wavelength of 1548 km, and also propagates in the southeasterly direction. The scale and speed of these disturbances suggests that they are large scale TIDs. These data will be compared to complementary GPS, coherent back-scatter radar, and ionosonde data. This study confirms the use of AM radio transmissions as a viable method for TID identification, tracking, and analysis.

Reference: Chilcote, M., et al. (2015), Detection of traveling ionospheric disturbances by medium-frequency Doppler sounding using AM radio transmissions, Radio Sci., 50, doi:10.1002/2014RS005617.

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