TY - CONF T1 - Amateur Radio Communications as a Novel Sensor of Large Scale Traveling Ionospheric Disturbances (Invited) T2 - American Geophysical Union Fall Meeting Y1 - 2021 A1 - Frissell, Nathaniel A. A1 - Sanchez, Diego F. A1 - Perry, Gareth W. A1 - Kaeppler, Steven R. A1 - Joshi, Dev Raj A1 - Engelke, William A1 - Thomas, Evan G. A1 - Coster, Anthea J. A1 - Erickson, Philip J. A1 - Ruohoniemi, J. Michael A1 - Baker, Joseph B. H. AB -

Amateur (ham) radio high frequency (HF) communications are routinely observed by automated receiving systems on a quasi-global scale. As these signals are modulated by the ionosphere, it is possible to use these observations to remotely sense ionospheric dynamics and the coupled geospace environment. In this presentation, we demonstrate the use of these data to observe Large Scale Traveling Ionospheric Disturbances (LSTIDs), which are quasi-periodic variations in F region electron density with horizontal wavelengths > 1000 km and periods between 30 to 180 min. On 3 November 2017, LSTID signatures were detected simultaneously over the continental United States in observations made by global HF amateur radio observing networks and the Blackstone (BKS) SuperDARN radar. The amateur radio LSTIDs were observed on the 7 and 14 MHz amateur radio bands as changes in average propagation path length with time, while the LSTIDs were observed by SuperDARN as oscillations of average scatter range. LSTID period lengthened from T ~ 1.5 hr at 12 UT to T ~ 2.25 hr by 21 UT. The amateur radio and BKS SuperDARN radar observations corresponded with Global Navigation Satellite System differential Total Electron Content (GNSS dTEC) measurements. dTEC was used to estimate LSTID parameters: horizontal wavelength 1136 km, phase velocity 1280 km/hr, period 53 min, and propagation azimuth 167°. The LSTID signatures were observed throughout the day following ~400 to 800 nT surges in the Auroral Electrojet (AE) index. As a contrast, 16 May 2017 was identified as a period with significant amateur radio coverage but no LSTID signatures in spite of similar geomagnetic conditions and AE activity as the 3 November event. We hypothesize that atmospheric gravity wave (AGW) sources triggered by auroral electrojet intensifications and associated Joule heating are the source of the LSTIDs, and discuss possible reasons why LSTIDs were observed in November but not May.

JF - American Geophysical Union Fall Meeting PB - American Geophysical Union CY - New Orleans, LA UR - https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/822746 ER - TY - Generic T1 - Experimental and Computational Methods to Analyze Complex Doppler Behavior of Ionospherically Induced Doppler Shifts on HF Signals (Proceedings) T2 - ARRL-TAPR Digital Communications Conference Y1 - 2021 A1 - Cerwin, Stephen A. A1 - Collins, Kristina V. A1 - Joshi, Dev Raj A1 - Frissell, Nathaniel A. JF - ARRL-TAPR Digital Communications Conference PB - ARRL-TAPR CY - Virtual UR - https://youtu.be/MHkz7jNynOg?t=18161 ER - TY - CONF T1 - Experimental and Computational Methods to Analyze Complex Doppler Behavior of Ionospherically Induced Doppler Shifts on HF Signals T2 - American Geophysical Union Fall Meeting Y1 - 2021 A1 - Cerwin, Stephen A. A1 - Collins, Kristina V. A1 - Joshi, Dev Raj A1 - Frissell, Nathaniel A. AB -

The HamSCI community has been studying apparent frequency shifts in the reception of HF skywave signals from radio station WWV in Ft. Collins, CO. Causes for frequency shifts in the received signal are recognized as complex and varied. Leading candidates are Doppler shifts resulting from dynamic changes in refraction layer height and the behavior of modes at incidence angles at the cusp between escape into space and refraction back to earth. Observations have shown the most radical frequency disturbances occur during the diurnal transitions between night and day, with the morning transitions exhibiting more radical behavior than evening. Other changes in solar radiation such as passage of an eclipse shadow or solar flares produce similar results. In all cases the frequency swings were found to follow the rate of change of propagation path length. Specific behaviors studied include mode splitting, where the Doppler shift diverges into multiple overtone-related tracks, modes that abruptly manifest and disappear during the transition, and asymptotic behavior where Doppler tracks exhibit a rapid frequency change followed by extinction. A morning transition spectrogram showing some of these characteristics is shown in the accompanying figure. This paper describes experiments and analytical procedures devised to better understand these phenomena. They include Time-of-Flight measurements reconciled with a geometric model of the ionosphere to infer propagation modes, use of the geometric model to calculate layer height changes from measured Doppler shifts, and comparison of specific features between spectrogram and ionosonde data sets. Data from two morning transitions and the 2017 total eclipse are given. Plausible explanations for several aspects of observed frequency swings are postulated.

JF - American Geophysical Union Fall Meeting PB - American Geophysical Union CY - New Orleans, LA UR - https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/849071 ER - TY - Generic T1 - HamSCI: Ham Radio Science Citizen Investigation T2 - ISWAT Meeting Y1 - 2021 A1 - Frissell, Nathaniel A. A1 - Sanchez, Diego A1 - Perry, Gareth W. A1 - Kaeppler, Stephen R. A1 - Joshi, Dev Raj A1 - Engelke, William D. A1 - Thomas, Evan G. A1 - Coster, Anthea J. A1 - Erickson, Philip J. A1 - Ruohoniemi, J. Michael A1 - Baker, Joseph B. H. A1 - Gerzoff, Robert JF - ISWAT Meeting PB - International Space Weather Action Team (ISWAT) CY - Virtual ER - TY - Generic T1 - HamSCI Personal Space Weather Station (PSWS): Fall 2021 Update T2 - TAPR-ARRL Digital Communications Conference Y1 - 2021 A1 - Frissell, Nathaniel A. A1 - Joshi, Dev Raj A1 - Collins, Kristina A1 - Montare Aidan A1 - Kazdan, David A1 - Engelke, William D. A1 - Atkison, Travis A1 - Kim, Hyomin A1 - Cowling, Scott H. A1 - McDermott, Thomas C. A1 - Ackermann, John A1 - Witten, David A1 - Madey, Jules A1 - Silver, H. Ward A1 - Liles, W. A1 - Cerwin, Stephen A. A1 - Erickson, Phillip J. A1 - Miller, Ethan S, A1 - Vierinen, Juha JF - TAPR-ARRL Digital Communications Conference PB - ARRL-TAPR CY - Virtual UR - https://youtu.be/MHkz7jNynOg?t=1990 ER - TY - Generic T1 - HF Doppler Observations of Traveling Ionospheric Disturbances in the WWV Signal Received with a Network of Low-Cost HamSCI Personal Space Weather Stations T2 - ARRL-TAPR Digital Communications Conference Y1 - 2021 A1 - Romanek, Veronica I. A1 - Frissell, Nathaniel A. A1 - Joshi, Dev Raj A1 - Liles, William A1 - Trop, Claire A1 - Collins, Kristina A1 - Perry, Gareth W. JF - ARRL-TAPR Digital Communications Conference PB - ARRL-TAPR CY - Virtual UR - https://youtu.be/kVY3E3e--_I?t=3495 ER - TY - CONF T1 - HF Doppler Observations of Traveling Ionospheric Disturbances in the WWV Signal Received with a Network of Low-Cost HamSCI Personal Space Weather Stations T2 - American Geophysical Union Fall Meeting Y1 - 2021 A1 - Romanek, Veronica I. A1 - Frissell, Nathaniel A. A1 - Joshi, Dev Raj A1 - Liles, William A1 - Trop, Clair A1 - Collins, Kristina A1 - Perry, Gareth W. AB -

Traveling Ionospheric Disturbances (TIDs) are quasi-periodic variations in ionospheric electron density that are often associated with atmospheric gravity waves. TIDs cause amplitude and frequency variations in high frequency (HF, 3-30 MHz) refracted radio waves. We present observations of TIDs made with a network of Ham Radio Science Citizen Investigation (HamSCI) Low-Cost Personal Space Weather Stations (PSWS) with nodes located in Pennsylvania, New Jersey, and Ohio. The TIDs were detected in the Doppler shifted carrier of the received signal from the WWV frequency and time standard station near Fort Collins, CO. Using a lagged cross correlation analysis, we demonstrate a method for determining TID wavelength, direction, and period using the collected WWV HF Doppler shifted data.

JF - American Geophysical Union Fall Meeting PB - American Geophysical Union CY - New Orleans, LA UR - https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/888443 ER - TY - Generic T1 - Observations of Mid-latitude Irregularities Using the Oblique Ionosonde Sounding Mode for the HamSCI Personal Space Weather Station (Proceedings) T2 - ARRL-TAPR Digital Communications Conference Y1 - 2021 A1 - Joshi, Dev Raj A1 - Frissell, Nathaniel A. A1 - Liles, William A1 - Vierinen, Juha JF - ARRL-TAPR Digital Communications Conference PB - ARRL-TAPR CY - Virtual UR - https://youtu.be/kVY3E3e--_I?t=2542 ER - TY - CONF T1 - Observations of Mid-latitude Irregularities Using the Oblique Ionosonde Sounding Mode for the HamSCI Personal Space Weather Station T2 - American Geophysical Union Fall Meeting Y1 - 2021 A1 - Joshi, Dev Raj A1 - Frissell, Nathaniel A. A1 - Sarwar, M. Shaaf A1 - Sami, Simal A1 - Ruohoniemi, J. Michael A1 - Baker, Joseph B. H. A1 - Coster, Anthea J. A1 - Erickson, Philip J. A1 - Liles, William A1 - Vierinen, Juha A1 - Groves, Keith AB -

The spread in the echoes of high-frequency (HF, 3-30 MHz) radio waves from the F-region of the ionosphere was one of the earliest indications of plasma density irregularities in the mid-latitude F region ionosphere. Although mid-latitude spread F has been widely studied, the plasma instability mechanisms that create these irregularities are still largely unknown. This phenomenon can cause radio wave scintillation effects that degrade the performance of human-made technologies such as satellite communications and Global Navigation Satellite Systems (GNSS). Understanding these irregularities so that they can be anticipated and mitigated are important aspects of space weather research. The occurrence climatology and variability can also be helpful in validating models of these irregularities. Here, we present signatures of mid-latitude irregularities observed in oblique ionograms received near Scranton, PA transmitted by the Relocatable Over-the-Horizon Radar (ROTHR) in Chesapeake, Virginia. These observations are collected with the GNU Chirpsounder2 software, an open source software package capable of creating ionograms from frequency modulated (FM) chirp ionosondes. This ionospheric sounding mode will be implemented in the currently under-development Ham Radio Science Citizen Investigation (HamSCI) Personal Space Weather Station (PSWS), a ground-based multi-instrument system designed to remote-sense the ionosphere using signals of opportunity. Using the data from the oblique ionograms, we generate the Range Time Intensity (RTI) plots that show ionospheric dynamics through measured path length variations as a function of time. We also compare the RTI plots with Range-Time-Parameter (RTP) plots from the SuperDARN HF radar in Blackstone, Virginia which commonly observes direct backscatter from decameter-scale irregularities within the region of ionosphere traversed by the ROTHR signal.

JF - American Geophysical Union Fall Meeting PB - American Geophysical Union CY - New Orleans, LA UR - https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/875589 ER - TY - Generic T1 - Simultaneous observations of mid-latitude Ionospheric Irregularities in HamSCI Personal Space Weather Station and SuperDARN radar T2 - SuperDARN Workshop Y1 - 2021 A1 - Joshi, Dev Raj A1 - Frissell, Nathaniel A. A1 - Liles, William A1 - Vierinen, Juha JF - SuperDARN Workshop PB - SANSA CY - Virtual UR - https://www.sansa.org.za/events-outreach/superdarn-workshop-2021/ ER - TY - Generic T1 - Sources of Large Scale Traveling Ionospheric Disturbances Observed using HamSCI Amateur Radio, SuperDARN, and GNSS TEC T2 - SuperDARN Workshop Y1 - 2021 A1 - Frissell, Nathaniel A. A1 - Sanchez, Diego F. A1 - Perry, Gareth W. A1 - Joshi, Dev Raj A1 - Engelke, William D. A1 - Thomas, Evan G. A1 - Coster, Anthea J. A1 - Erickson, Philip J. A1 - Ruohoniemi, J. Michael A1 - Baker, Joseph B. H. JF - SuperDARN Workshop PB - SANSA CY - Virtual UR - https://www.sansa.org.za/events-outreach/superdarn-workshop-2021/ ER - TY - Generic T1 - Sources of Large Scale Traveling Ionospheric Disturbances Observed using HamSCI Amateur Radio, SuperDARN, and GNSS TEC T2 - ARRL-TAPR Digital Communications Conference Y1 - 2021 A1 - Frissell, Nathaniel A. A1 - Sanchez, Diego F. A1 - Perry, Gareth W. A1 - Kaeppler, Stephen R. A1 - Joshi, Dev Raj A1 - Engelke, William D. A1 - Thomas, Evan G. A1 - Coster, Anthea J. A1 - Erickson, Philip J. A1 - Ruohoniemi, J. Michael A1 - Baker, Joseph B. H. JF - ARRL-TAPR Digital Communications Conference PB - ARRL-TAPR CY - Virtual UR - https://youtu.be/MHkz7jNynOg?t=22608 ER -