TY - JOUR
AU - Steve Cerwin
AB - The author recently participated in the HamSCI propagation experiments during the August 2017 total solar eclipse, and the ARRL November 2017 Frequency Measuring Test (FMT). This article presents some interesting propagation phenomena observed during both activities. For the eclipse experiment, well-defined propagation enhancements of both 60 kHz WWVB and 5 MHz WWV for a path between Ft. Collins, CO and San Antonio, TX were documented. Additionally, deep propagation nulls of WWVB over this path were observed to occur every morning and evening, suggesting predictable multipath interference between competing daytime and nighttime modes. During the Frequency Measuring Test, propagation-induced frequency variations of 5 MHz WWV were observed at night and especially during dawn and dusk. One observed dawn frequency perturbation was particularly interesting because it occurred at a fundamental frequency shift plus two harmonically related overtones, indicating a nonlinear ionospheric response to rapidly increasing solar radiation.
BT - QEX
C1 - <p><a href="http://hamsci.org/sites/default/files/publications/2018_QEX_Cerwin_Eclipse">2018_QEX_Cerwin_Eclipse</a></p>

<p><span style="color:rgb(0, 0, 0); font-family:arial,sans-serif; font-size:14.6667px">Reprinted with permission; September/October 2018 QEX, copyright ARRL.</span></p>

DA - 09/2018
IS - 310
LA - eng
M1 - 310
N2 - The author recently participated in the HamSCI propagation experiments during the August 2017 total solar eclipse, and the ARRL November 2017 Frequency Measuring Test (FMT). This article presents some interesting propagation phenomena observed during both activities. For the eclipse experiment, well-defined propagation enhancements of both 60 kHz WWVB and 5 MHz WWV for a path between Ft. Collins, CO and San Antonio, TX were documented. Additionally, deep propagation nulls of WWVB over this path were observed to occur every morning and evening, suggesting predictable multipath interference between competing daytime and nighttime modes. During the Frequency Measuring Test, propagation-induced frequency variations of 5 MHz WWV were observed at night and especially during dawn and dusk. One observed dawn frequency perturbation was particularly interesting because it occurred at a fundamental frequency shift plus two harmonically related overtones, indicating a nonlinear ionospheric response to rapidly increasing solar radiation.
PY - 2018
SE - 8
SP - 8
EP - 14
T2 - QEX
TI - Ionospheric Disturbances at Dawn, Dusk, and During the 2017 Eclipse
SN - 0886-8093
ER -