TY - Generic T1 - Plans to Observe Changes to the Ionosphere During the April 8 Eclipse Using Doppler Shifts of AM Broadcast Stations T2 - HamSCI Workshop 2024 Y1 - 2024 A1 - David McGaw A1 - James LaBelle A1 - John Griffin A1 - Terrence Kovacs A1 - Margaret Klein A1 - Jack Bonneau A1 - Justin Lewis A1 - Jackson Gosler AB -

Variations in the ionosphere can be tracked by observing the Doppler-shifted carriers of clear-channel AM broadcast stations.  An expansive system of receivers using Software-Defined Radios, frequency stabilized by GPS is being deployed to collect data in the eastern United States.  This network is expected to be able to detect and track changes due to the shadow of the April 8, 2024 Total Eclipse of the Sun.

JF - HamSCI Workshop 2024 PB - HamSCI CY - Cleveland, OH ER - TY - Generic T1 - Traveling ionospheric disturbances tracked through Doppler-shifted AM radio transmissions T2 - HamSCI Workshop 2021 Y1 - 2021 A1 - Claire C. Trop A1 - James LaBelle A1 - Philip J. Erickson A1 - Shunrong Zhang A1 - David McGaw A1 - Terrence Kovacs AB -

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), dawn and dusk signal divergence (terminators), and spread F 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 have been operational from 3/19/20 to the present and Doppler-shifted signals, attributed to TID events, have been consistently visible across several radio channels with frequencies between 800 to 1600kHz. We have focused our study thus far on the terminator signals which appear to be consistent with photochemistry effects and on TID wave characteristic analysis. We have collected a set of exceptional TID events over the past nine months and have correlated our calculated wave characteristics with the data from GNSS TEC, digisonde, and SuperDARN in general finding good agreement between our technique and these established methods. While our study still seeks to clarify discrepancies in our data similar to those seen by Chilcote in the original study, the consistency with which our data typically agrees with other methods supports the validity of using AM radio transmissions to track TIDs in addition to other ionospheric phenomena such as the terminator. 

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.

JF - HamSCI Workshop 2021 PB - HamSCI CY - Scranton, PA (Virtual) ER -