@proceedings {628, title = {Climatology of Large Scale Traveling Ionospheric Disturbances Observed by HamSCI Amateur Radio with Connections to Geospace and Neutral Atmospheric Sources}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

Traveling Ionospheric Disturbances (TIDs) are propagating variations of F-region ionospheric electron densities that can affect the range and quality of High Frequency (HF, 3-30 MHz) radio communications. TIDs create concavities in the ionospheric electron density profile that move horizontally with the TID and cause skip-distance focusing effects for high frequency radio signals propagating through the ionosphere. TIDs are of great interest scientifically because they are often associated with neutral Atmospheric Gravity Waves (AGWs) and can be used to advance understanding of atmosphere-ionosphere coupling. Large scale TIDs (LSTIDs) have periods of 30-180 min, horizontal phase velocities of 100 - 250 m/s, and horizontal wavelengths of over 1000 km and are believed to be generated either by geomagnetic activity or lower atmospheric sources. The signature of this phenomena is manifest as quasi-periodic variations in contact ranges in HF amateur radio communication reports recorded by automated monitoring systems such as the Weak Signal Propagation Reporting Network (WSPRNet) and the Reverse Beacon Network (RBN). Current amateur radio observations are only able to detect LSTIDs. In this study, we present a climatology of LSTID activity using RBN and WSPRNet observations on the 1.8, 3.5, 7, 14, 21, and 28 MHz amateur radio bands from 2017. Results will be organized as a function observation frequency, longitudinal sector (North America and Europe), season, and geomagnetic activity level. Connections to geospace are explored via SYM-H and Auroral Electrojet indexes, while neutral atmospheric sources are explored using NASA{\textquoteright}s Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2).

}, author = {Diego S. Sanchez and Nathaniel A. Frissell and Gareth W. Perry and V. Lynn Harvey and William D. Engelke and Anthea Coster and Philip J. Erickson and J. Michael Ruohoniemi and Joseph B. H. Baker} } @proceedings {624, title = {Detecting Large Scale Traveling Ionospheric Disturbances using Feature Recognition and Amateur Radio Data}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

A Large-Scale Transient Ionospheric Disturbance (LSTID) is a traveling perturbation in ionosphere electron density with a horizontal wavelength of approximately 1000 km and a period between 30 to 180 minutes. These can be detected by SuperDARN HF radar and GNSS Total Electron Content measurements. Recently it has been discovered that these can also be detected in amateur (ham) radio signal reports, which are now being generated in vast numbers by operators world-wide. A machine-learning technique was developed to find patterns in these data that indicate the presence of LSTIDs using an object detection technique.

}, author = {William D. Engelke and Nathaniel A. Frissell and Travis Atkison and Philip J. Erickson and Francis Tholley} } @conference {550, title = {HamSCI Campaign Co-Design (Panel Discussion)}, booktitle = {HamSCI Workshop 2021}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, organization = {HamSCI}, address = {Virtual}, author = {Kristina V. Collins and Nathaniel A. Frissell and Philip J. Erickson and Laura Brandt and Elizabeth MacDonald and Michael Black and Gareth Perry} } @conference {544, title = {HamSCI Personal Space Weather: Architecture and Applications to Radio Astronomy}, booktitle = {Annual (Summer) Eastern Conference}, year = {2021}, month = {07/2021}, publisher = {Society of Amateur Radio Astronomers (SARA)}, organization = {Society of Amateur Radio Astronomers (SARA)}, address = {Virtual}, abstract = {

The Ham Radio Science Citizen Investigation (HamSCI) Personal Space Weather Station (PSWS) project is a citizen science initiative to develop a new modular set of ground-based instrumentation for the purpose of studying the structure and dynamics of the terrestrial ionosphere, as well as the larger, coupled geospace system. PSWS system instrumentation includes radio receivers sensitive to frequencies ranging from the very low frequency (VLF) through very high frequency (VHF) bands, a Global Navigation Satellite System (GNSS) receiver to provide Total Electron Content (TEC) measurements and serve as a precision time and frequency reference, and a ground magnetometer sensitive to ionospheric and geospace currents. Although the PSWS is designed primarily for space weather and space science, its modular and open design in both hardware and software allows for a variety of use cases. The core radio instrument of the PSWS, the TangerineSDR, is a wideband, direct sampling 100~kHz to 60~MHz field programmable gate array (FPGA)-based software defined radio (SDR) receiver with direct applicability to radio astronomy. In this paper, we describe the PSWS and TangerineSDR architecture, show examples of how the TangerineSDR could be used to observe Jovian decametric emission, and discuss the applicability of the TangerineSDR to radio astronomy in general.

}, url = {https://rasdr.org/store/books/books/journals/proceedings-of-annual-conference}, author = {Nathaniel A. Frissell and Scott H. Cowling and Thomas C. McDermott and John Ackermann and David Typinski and William D. Engelke and David R. Larsen and David G. McGaw and Hyomin Kim and David M. Witten, II and Julius M. Madey and Kristina V. Collins and John C. Gibbons and David Kazdan and Aidan Montare and Dev Raj Joshi and Veronica I. Romanek and Cuong D. Nguyen and Stephen A. Cerwin and William Liles and Jonathan D. Rizzo and Ethan S. Miller and Juha Vierinen and Philip J. Erickson and Mary Lou West} } @conference {540, title = {HamSCI Personal Space Weather Station (PSWS): Architecture and Current Status}, booktitle = {NSF CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions)}, year = {2021}, month = {06/2021}, publisher = {CEDAR}, organization = {CEDAR}, address = {Virtual}, abstract = {

Recent advances in geospace remote sensing have shown that large-scale distributed networks of ground-based sensors pay large dividends by providing a big picture view of phenomena that were previously observed only by point-measurements. While existing instrument networks provide excellent insight into ionospheric and space science, the system remains undersampled and more observations are needed to advance understanding. In an effort to generate these additional measurements, the Ham Radio Science Citizen Investigation (HamSCI, hamsci.org) is working with the Tucson Amateur Packet Radio Corporation (TAPR, tapr.org), an engineering organization comprised of volunteer amateur radio operators and engineers, to develop a network of Personal Space Weather Stations (PSWS). These instruments that will provide scientific-grade observations of signals-of-opportunity across the HF bands from volunteer citizen observers as part of the NSF Distributed Array of Small Instruments (DASI) program. A performance-driven PSWS design (~US$500) will be a modular, multi-instrument device that will consist of a dual-channel phase-locked 0.1-60 MHz software defined radio (SDR) receiver, a ground magnetometer with (~10 nT resolution and 1-sec cadence), and GPS/GNSS receiver to provide precision time stamping and serve as a GPS disciplined oscillator (GPSDO) to provide stability to the SDR receiver. A low-cost PSWS (\< US$100) that measures Doppler shift of HF signals received from standards stations such as WWV (US) and CHU (Canada) and includes a magnetometer is also being developed. HF sounding algorithms making use of signals of opportunity will be developed for the SDR-based PSWS. All measurements will be collected into a central database for coordinated analysis and made available for public access.

}, author = {Nathaniel A. Frissell and Dev Joshi and Veronica I. Romanek and Kristina V. Collins and Aidan Montare and David Kazdan and John Gibbons and William D. Engelke and Travis Atkison and Hyomin Kim and Scott H. Cowling and Thomas C. McDermott and John Ackermann and David Witten and Julius Madey and H. Ward Silver and William Liles and Steven Cerwin and Philip J. Erickson and Ethan S. Miller and Juha Vierinen} } @conference {537, title = {Observing Large Scale Traveling Ionospheric Disturbances using HamSCI Amateur Radio: Climatology with Connections to Geospace and Neutral Atmospheric Sources}, booktitle = {NSF CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions)}, year = {2021}, month = {06/2021}, publisher = {CEDAR}, organization = {CEDAR}, address = {Virtual}, abstract = {

Large Scale Traveling lonospheric Disturbances (TIDs) are propagating variations in ionospheric electron densities that affect radio communications. LSTIDs create concavities in the ionospheric electron density profile that move horizontally with the LSTID and cause skip-distance focusing effects for high frequency (HF, 3-30 MHz) radio signals propagating through the ionosphere. This phenomena manifests as quasi-periodic variations in contact ranges in HF amateur radio communications recorded by automated monitoring systems such as RBN and WSPRNet. In this study, members of the Ham Radio Science Citizen Investigation (HamSCI) present a climatology of LSTID activity as well as using RBN and WSPRNet observations on the 1.8, 3.5, 7, 14, 21, and 28 MHz amateur radio bands from 2017. Results will be organized as a function observation frequency, longitudinal sector, season, and geomagnetic activity level. Connections to neutral atmospheric sources are also explored.

}, author = {Diego F. Sanchez and Nathaniel A. Frissell and Gareth W. Perry and William D. Engelke and Anthea Coster and Philip J. Erickson and J. Michael Ruohoniemi and Joseph B. H. Baker} } @proceedings {465, title = {Observing Traveling Ionospheric Disturbances using HamSCI Amateur Radio: Validation and Climatology}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

Traveling lonospheric Disturbances (TIDs) are propagating variations in ionospheric electron densities that affect radio communications and can help with understanding energy transport throughout the coupled magnetosphere-ionosphere-neutral atmosphere system. Large scale TIDs (LSTIDs) have periods T\ \approx30-180\ min, horizontal phase velocities v_H\approx‍100-‍250 m/s, and horizontal wavelengths \lambda_H\>1000 km and are believed to be generated either by geomagnetic activity or lower atmospheric sources. TIDs create concavities in the ionospheric electron density profile that move horizontally with the TID and cause skip-distance focusing effects for high frequency (HF, 3-30 MHz) radio signals propagating through the ionosphere. The signature of this phenomena is manifest as quasi-periodic variations in contact ranges in HF amateur radio communication reports recorded by automated monitoring systems such as the Weak Signal Propagation Reporting Network (WSPRNet) and the Reverse Beacon Network (RBN). First in this study, members of the Ham Radio Science Citizen Investigation (HamSCI) present a case study showing consistency in LSTID signatures in RBN and WSPRNet are also present in Super Dual Auroral Radar Network (SuperDARN), Global Navigation Satellite System (GNSS), and ionosonde measurements. Then, we present a climatology of LSTID activity as well as\  using RBN and WSPRNet observations on the 1.8, 3.5, 7, 14, 21, and 28 MHz amateur radio bands from 2017. Results will be organized as a function observation frequency, longitudinal sector (North America and Europe), season, and geomagnetic activity level.

}, author = {Diego F. Sanchez and Nathaniel A. Frissell and Gareth W. Perry and William D. Engelke and Anthea Coster and Philip J. Erickson and J. Michael Ruohoniemi and Joseph B. H. Baker} } @conference {542, title = {Sources of Large Scale Traveling Ionospheric Disturbances Observed using HamSCI Amateur Radio, SuperDARN, and GNSS TEC}, booktitle = {NSF CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions)}, year = {2021}, month = {06/2021}, publisher = {CEDAR}, organization = {CEDAR}, address = {Virtual}, abstract = {

Large Scale Traveling Ionospheric Disturbances (LSTIDs) 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 in simultaneously over the continental United States in observations made by global High Frequency (HF) amateur (ham) 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{\textdegree}. 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 that seasonal neutral atmospheric conditions may play a role in preventing AGW propagation in May but not in November.

}, author = {Nathaniel A. Frissell and Diego F. Sanchez and Gareth W. Perry and Dev Joshi and William D. Engelke and Evan G. Thomas and Anthea Coster and Philip J. Erickson and J. Michael Ruohoniemi and Joseph B. H. Baker} } @proceedings {505, title = {Survey of ionospheric F2 region variability from the lower atmosphere: drivers and responses - Part 1}, year = {2021}, month = {03/2021}, abstract = {

Carl Luetzelschwab, K9LA, will review the factors that cause the F2 region of the ionosphere to vary in the short-term, on day-to-day and even shorter time scales. These factors can directly affect amateur radio operators through their influence on electron density and therefore on HF propagation. Ionospheric variability drivers will be sorted into three broad categories: 1) solar radiation 2) geomagnetic activity and 3) meteorological sources (neutral atmosphere). Carl will also assess how much F2 ionospheric parameters vary in the short-term during both day and night, and he will also review the contribution of each of the factors to observed F2 region variability.

}, author = {R. Carl Luetzelschwab and Philip J. Erickson} } @proceedings {506, title = {Survey of ionospheric F2 region variability from the lower atmosphere: drivers and responses - Part 2}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

Phil Erickson, W1PJE, will follow with a condensed summary of recent community research on the types of physical processes that produce F2 layer ionospheric variations from waves, heating, and other sources in the lower neutral atmosphere (space weather {\textquotedblleft}from below{\textquotedblright}). Examples will include acoustic waves, gravity waves, planetary waves, TADs (traveling atmospheric disturbances), and their influence on TIDs (travelling ionospheric disturbances). Numerical estimates of the various forcing terms provide a useful gauge of the relative importance and impact of these processes. Phil will close by specifically focusing on estimates of the magnitude of electron density variations in the F2 region of the ionosphere due to earthquake effects. In particular, ionospheric density observations from sources such as the global satellite navigation system (GNSS) allow a quantitative, numerate discussion of earthquake drivers in both time and space dimensions as compared to other known lower atmosphere ionospheric variability drivers.\  Phil will conclude with a discussion of the implications for earthquake associated HF propagation effects in the face of observed day-to-day ionospheric density variability.

}, author = {Philip J. Erickson and R. Carl Luetzelschwab} } @proceedings {464, title = {Traveling ionospheric disturbances tracked through Doppler-shifted AM radio transmissions}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, 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), 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.

}, author = {Claire C. Trop and James LaBelle and Philip J. Erickson and Shunrong Zhang and David McGaw and Terrence Kovacs} } @conference {359, title = {HamSCI: Space Weather Operational Resources and Needs of the Amateur Radio Community}, booktitle = {American Meteorological Society Annual Meeting}, year = {2020}, month = {01/2020}, publisher = {American Meteorological Society Annual Meeting}, organization = {American Meteorological Society Annual Meeting}, address = {Boston, MA}, abstract = {

The amateur (ham) radio community is a global community of over 3 million people who use and build radio equipment for communications, experimentation, and science. By definition, amateur radio is a volunteer service, with the operators required to hold government-issued licenses that are typically earned by passing knowledge tests covering radio regulations and practices, radio theory, and electromagnetic theory. In the United States, there are about 750,000 licensed hams, ranging in age from very young to very old, and ranging in experience from neophyte to people with advanced degrees in radio engineering and science. Amateur radio operators are licensed to transmit on bands spread across the radio frequency (RF) spectrum, from very low frequency (VLF) up to hundreds of gigahertz. The purpose of these communications range from mission-critical emergency and public service communications to social contacts to highly competitive contests and achievement award programs. Many of these communications rely on trans-ionospheric paths, and therefore are heavily influenced by conditions in near-Earth space, or space weather.
Amateurs today obtain space weather and propagation prediction information from sources such as the NOAA Space Weather Prediction Center (SWPC), spaceweather.com, the Voice of America Coverage Analysis Program (VOACAP), amateur radio propagation columnists (ARRL, RSGB, and CQ Magazine), and spaceweatherwoman.com (Dr. Tamitha Skov). In order to predict success for their communications efforts, hams often use parameters such as smoothed sunspot number, 10.7 cm wavelength solar flux proxy, and the planetary Kp and Ap indices as inputs to predict radio propagation performance. Traditionally, these predictions focus on the driving influence of space conditions and the sun{\textquoteright}s output. However, frontier research in the space sciences community has revealed that for improved predictive success, much more information needs to be provided on neutral atmosphere dynamics from the lower atmosphere and its coupled effects on the ionosphere, and predictions need to be available at higher temporal and spatial resolution. Lower atmospheric influences include atmospheric gravity waves that can couple to traveling ionospheric disturbances that can dramatically alter radio propagation paths. Tropospheric phenomena such as temperature inversions and wind shear also affect VHF and UHF propagation. To be most useful, the ham community needs operational products that provide real time nowcasts and multi-day forecasts which predict how space weather through the whole atmosphere affects radio wave propagation on global scale and at all operational wavelengths.
To help with this effort, hams can provide data with unique spatial and temporal coverage back to the research and forecast community. The amateur radio community has already started this process with the creation of multiple global-scale, real-time propagation reporting systems such as the Weak Signal Propagation Reporting Network (WSPRNet), PSKReporter, and the Reverse Beacon Network (RBN). Studies by the Ham radio Science Citizen Investigation (HamSCI) have shown that data from these systems, if applied correctly, can effectively be used to study ionospheric space weather events. Experienced amateurs keep detailed records of verified point-to-point contacts and have extensive experience operating under a wide variety of geophysical conditions and locations, both of which can provide unique insights when shared with the professional research community. In this presentation, we will describe efforts led by the HamSCI collective to provide this research community feedback through active HamSCI community email lists and annual HamSCI workshops. We will also describe strategies with good initial success at amateur-professional collaboration, including a HamSCI-led amateur radio community - professional research community partnership to create a network of HamSCI Personal Space Weather Stations (PSWS), which will allow citizen scientists to make science-grade space weather observations from their own backyards.

}, url = {https://ams.confex.com/ams/2020Annual/meetingapp.cgi/Paper/370904}, author = {Nathaniel A. Frissell and Philip J. Erickson and Ethan S. Miller and William Liles and H. Ward Silver and R. Carl Luetzelschwab and Tamitha Skov} } @conference {295, title = {High Frequency Communications Response to Solar Activity in September 2017 as Observed by Amateur Radio Networks}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

Numerous solar flares and coronal mass ejection-induced interplanetary shocks associated with solar active region AR12673 caused disturbances to terrestrial high-frequency (HF, 3{\textendash}30 MHz) radio communications from 4{\textendash}14 September 2017. Simultaneously, Hurricanes Irma and Jose caused significant damage to the Caribbean Islands and parts of Florida. The coincidental timing of both the space weather activity and hurricanes was unfortunate, as HF radio was needed for emergency communications. This paper presents the response of HF amateur radio propagation as observed by the Reverse Beacon Network and the Weak Signal Propagation Reporting Network to the space weather events of that period. Distributed data coverage from these dense sources provided a unique mix of global and regional coverage of ionospheric response and recovery that revealed several features of storm time HF propagation dynamics. X-class flares on 6, 7, and 10 September caused acute radio blackouts during the day in the Caribbean with recovery times of tens of minutes to hours, based on the decay time of the flare. A severe geomagnetic storm with Kpmax = 8+ and SYM-Hmin = -146 nT occurring 7{\textendash}10 September wiped out ionospheric communications first on 14 MHz and then on 7 MHz starting at \~{}1200 UT 8 September. This storm, combined with affects from additional flare and geomagnetic activity, contributed to a significant suppression of effective HF propagation bands both globally and in the Caribbean for a period of 12 to 15 days.

}, author = {Nathaniel A. Frissell and Joshua S. Vega and Evan Markowitz and Andrew J. Gerrard and William D. Engelke and Philip J. Erickson and Ethan S. Miller and R. Carl Luetzelschwab and Jacob Bortnik} } @conference {329, title = {IonTV: Using WWV Timing Reference Signals to Observe Ionospheric Variation}, booktitle = {Hamvention HamSCI Forum}, year = {2019}, month = {05/2019}, publisher = {Dayton Amateur Radio Association}, organization = {Dayton Amateur Radio Association}, address = {Xenia, OH}, abstract = {

For decades, an AM modulated time signal has been broadcast at multiple HF frequencies by the National Institute of Standards and Technology (NIST).\  Shortwave radio stations WWV in Colorado and WWVH in Hawaii use these frequencies for the broad dissemination of accurate coordinated universal time information.\  As the HF signal traverses the ionosphere, propagation effects ensue, and the high temporal precision of the original transmitted signal provides an attractive potential for wide-sense monitoring of ionospheric variations.\  We present the results of an ongoing set of data collections and statistical analysis of the received variation in WWV timing signals aimed at extracting ionospheric propagation effects.\  The work includes design of a software defined receiver (SDR) for processing the amplitude modulated dual sideband (AM-DSB) timing signal. By observing the time shift between consecutive seconds of the 10MHz WWV timing signal, reflected from the ionosphere, the change in the effective height of the ionosphere can be estimated.\  Simultaneous measurements taken from different observation angles allow a more accurate sensing of ionospheric electron density variability as projected into refractive effects.\  The project also has a goal of creating a straightforward and reliable way for hobbyists and citizen scientists to demodulate and process their own NIST timing data. We describe a sample analysis of several blocks of WWV received data, both on remote paths and locally through groundwave propagation near the Colorado transmit array, including simultaneous collects. To process the timing data, several approaches will be described, including a heterodyne SDR with a digital phase-locked-loop (PLL).\  Carrier offset tracking using PLL techniques produce Doppler shifts that are associated with traveling ionospheric disturbances and inherent electron density variability.\  Demodulation and amplitude/phase analysis of the 100 Hz subcarrier of WWV can also provide precise delta-time information on ionospheric propagation through examination of variability in arrival of the leading edge of 1 pulse-per-second ticks.\  Results to date suggest that variation between consecutive second markers is a uniformly distributed Gaussian random variable with at least some of this variation due to ionospheric factors, although systematics must be addressed.

}, author = {Philip J. Erickson and William Liles and J. Dusenbury and K.C. Kerby-Patel and Ethan Miller and Gary Bust and Cathryn Mitchell} } @conference {290, title = {IonTV: Using WWV Timing Reference Signals to Observe Ionospheric Variation}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

For decades, an AM modulated time signal has been broadcast at multiple HF frequencies by the National Institute of Standards and Technology (NIST).\  Shortwave radio stations WWV in Colorado and WWVH in Hawaii use these frequencies for the broad dissemination of accurate coordinated universal time information.\  As the HF signal traverses the ionosphere, propagation effects ensue, and the high temporal precision of the original transmitted signal provides an attractive potential for wide-sense monitoring of ionospheric variations.\  We present the results of an ongoing set of data collections and statistical analysis of the received variation in WWV timing signals aimed at extracting ionospheric propagation effects.\  The work includes design of a software defined receiver (SDR) for processing the amplitude modulated dual sideband (AM-DSB) timing signal. By observing the time shift between consecutive seconds of the 10MHz WWV timing signal, reflected from the ionosphere, the change in the effective height of the ionosphere can be estimated.\  Simultaneous measurements taken from different observation angles allow a more accurate sensing of ionospheric electron density variability as projected into refractive effects.\  The project also has a goal of creating a straightforward and reliable way for hobbyists and citizen scientists to demodulate and process their own NIST timing data. We describe a sample analysis of several blocks of WWV received data, both on remote paths and locally through groundwave propagation near the Colorado transmit array, including simultaneous collects. To process the timing data, several approaches will be described, including a heterodyne SDR with a digital phase-locked-loop (PLL).\  Carrier offset tracking using PLL techniques produce Doppler shifts that are associated with traveling ionospheric disturbances and inherent electron density variability.\  Demodulation and amplitude/phase analysis of the 100 Hz subcarrier of WWV can also provide precise delta-time information on ionospheric propagation through examination of variability in arrival of the leading edge of 1 pulse-per-second ticks.\  Results to date suggest that variation between consecutive second markers is a uniformly distributed Gaussian random variable with at least some of this variation due to ionospheric factors, although systematics must be addressed.

}, author = {Philip J. Erickson and William Liles and J. Dusenbury and K.C. Kerby-Patel and Ethan Miller and Gary Bust and Cathryn Mitchell} } @conference {361, title = {Large Scale Traveling Ionospheric Disturbances Observed using HamSCI Amateur Radio, SuperDARN, and GNSS TEC}, booktitle = {American Geophysical Union Fall Meeting}, year = {2019}, month = {12/2019}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {

Large Scale Traveling Ionospheric Disturbances (LSTIDs) 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 in observations made by Reverse Beacon Network (RBN) and the Weak Signal Propagation Reporting Network (WSPRNet) for the first time. The RBN and WSPRNet are two large-scale High Frequency (HF, 3-30 MHz) amateur (ham) radio observing networks that provide data to the Ham Radio Science Citizen Investigation (HamSCI). The LSTIDs were observed on the 7 and 14 MHz amateur radio bands, and are detected by observing changes in average propagation path length with time. LSTID period lengthened from T ~ 1.5 hr at 12 UT to T ~ 2.25 hr by 21 UT. Simultaneous LSTID signatures were present in ham radio observations over the continental United States, the Atlantic Ocean, and Europe. LSTIDs observed with amateur radio were consistent with LSTIDs observed by the Blackstone SuperDARN HF radar and in differential GNSS Total Electron Content (TEC) measurements. GNSS TEC maps were used to estimate LSTID parameters: horizontal wavelength 1100 km, phase velocity 950 km/hr, period 70 min, and propagation azimuth 135{\textdegree}. The LSTID signatures were observed throughout the day following ~800 nT surges in the Auroral Electrojet (AE) index at 00 and 12 UT. We will discuss potential generation hypotheses for the observed LSTIDs, including atmospheric gravity wave (AGW) sources triggered by auroral electrojet intensifications and associated Joule heating.

}, url = {https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/581488}, author = {Nathaniel A. Frissell and Diego F. Sanchez and Evan Markowitz and Gareth W. Perry and William D. Engelke and Anthea Coster and Philip J. Erickson and J. Michael Ruohoniemi and Joseph B. H. Baker} } @conference {360, title = {A Low-Cost Citizen Science HF Doppler Receiver for Measuring Ionospheric Variability}, booktitle = {American Geophysical Union Fall Meeting}, year = {2019}, month = {12/2019}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {

Advancement in understanding short term and small spatial scale ionospheric variability requires global high time and spatial resolution measurements. Professional ionospheric sounding networks are extensive and capable, yet more measurements are still needed due to the strongly magnetized nature and large extent of the ionosphere. High Frequency (HF, 3-30 MHz) radio signals are refracted by the ionosphere, and therefore are modulated by processes such as traveling ionospheric disturbances (TIDs) and geomagnetic storms. By measuring the amplitude and Doppler shift of trans-ionospheric HF signals, it is possible to detect signatures of ionospheric absorption and changes in propagation path length. We present a design for a low-cost citizen science HF multi-band receiver that measures the amplitude and Doppler shift of reference signals of opportunity from the US National Institute of Standards and Technology station WWV and the Canadian Institute for National Measurement Standards station CHU. The receiver will make 1 s cadence measurements on nine HF beacon frequencies and subsequently upload the results to a central server for scientific analysis. The local user will be able to review data daily, both locally and in aggregate on a web server, and participate in discussion of the ionospheric measurements. This receiver forms one component of the low-cost version of the Ham Radio Science Citizen Investigation (HamSCI) Personal Space Weather Station (PSWS), and is designed with the intention of distribution to hundreds to thousands of citizen science observers. Preliminary results from the prototype receiver will be presented.

}, url = {https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/602677}, author = {Kristina Collins and David Kazdan and John Gibbons and Aidan Montare and Skylar Dannhoff and Philip J. Erickson and Nathaniel A. Frissell} } @conference {315, title = {PSWS Science Requirements Panel Discussion (Panel)}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

Moderator: Ward Silver, N0AX

  1. Phil Erickson, W1PJE, MIT Haystack Observatory, Radio, Ionospheric, \& Magnetospheric Science
  2. Nathaniel Frissell, W2NAF, NJIT, Radio, Ionospheric, \& Magnetospheric Science
  3. Hyomin Kim, KD2MCR, NJIT, Magnetospheric Physics
  4. Bill Liles, NQ6Z, VLF Science
  5. John Ackermann, N8UR, TAPR, Radio Engineering
  6. Scotty Cowling, WA2DFI, TAPR, Radio Engineering
  7. Tom McDermott, N5EG, TAPR, Radio Engineering
}, author = {John Ackermann and Scotty Cowling and Philip J. Erickson and Nathaniel A. Frissell and Hyomin Kim and William Liles and Thomas McDermott and Ward Silver} } @conference {325, title = {Sounding the Ionosphere with Signals of Opportunity in the High-Frequency (HF) Band}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

The explosion of commercial off-the-shelf (COTS) education- and consumer-grade hardware supporting software-defined radio (SDR) over the past two decades has revolutionized many aspects of radio science, bringing the cost and calibration of traditionally complex receiver hardware within the grasp of even advanced amateur experimenters. Transmission has now become the limiter of access in many cases, particularly through spectrum management and licensing considerations. Fortunately, several classes of signals endemic to the HF band lend themselves to processing for ionospheric characteristics: time and frequency standard broadcasters, surface-wave oceanographic radars, amateur radio transmissions, and ionospheric sounders.

This presentation is a tour of these signals of opportunity and techniques for collecting and processing them into ionospheric characteristics, with emphasis on distributed receivers collecting on a small number (four or fewer) of coherent channels. Receiving techniques will be discussed for near-vertical ({\textquotedblleft}quasi-vertical{\textquotedblright}) incidence skywave (NVIS or QVI), long-distance oblique soundings, and transionospheric sounding. Soundings will be demonstrated from space-based, ground-based, and maritime platforms.

Binary, Doppler, delay, cone angle of arrival, and polarization observations will be exploited, depending on the signal type and capability of the collector. Each of these techniques conveys different, but not always {\textquotedblleft}orthogonal,{\textquotedblright} information about the ionospheric skywave channel. The information content of each datum will be discussed with respect to the implications for inverting the local or regional ionosphere from the observations. More importantly than inverting the full ionosphere, some of these techniques are sensitive indicators of ionospheric irregularities, structures, and instabilities, that might otherwise be difficult to study due to limited geographic coverage with larger, more exquisite instrumentation.

}, author = {Ethan S. Miller and Gary S. Bust and Gareth W. Perry and Stephen R. Kaeppler and Juha Vierinen and Nathaniel A. Frissell and A. A. Knuth and Philip J. Erickson and Romina Nikoukar and Alexander T. Chartier and P. Santos and C. Brum and J. T. Fentzke and T. R. Hanley and Andrew J. Gerrard} } @conference {162, title = {Upper Level Lows and Six Meter 50 Mhz Sporadic E}, booktitle = {Dayton Hamvention}, year = {2017}, address = {Xenia, OH}, abstract = {

Amateur radio is used to explore possible correlations between weather storm systems and sporadic E clouds to see if they are collocated. While some of the main causes of sporadic E propagation are wind shear, meteor strikes and upper atmospheric tides (ultimately coming from solar EUV energy inputs), radio operators have noticed that sporadic E propagation is also changed significantly by hurricanes and storms. \ Specific cases where K1YOW used amateur radio to investigate the effects of low pressure weather storms on the formation and/or enhancement of 6 meter sporadic E clouds are presented. DX Maps and earth wide weather model charts combined with operations on 6 meters are used to examine possible correlations between the location of the sporadic E clouds and the low pressure weather storm systems. \ Initial findings show a high degree of correlation when magnetic field strength is taken into consideration.

}, author = {Joseph A. Dzekevich and Philip J. Erickson} }