@proceedings {1041, title = {Meteor Scatter Science}, year = {2026}, month = {03/2026}, publisher = {HamSCI}, address = {Newington, CT}, author = {Robert Suggs} } @proceedings {1025, title = {Meteor Scatter Statistics: Theory vs. Practice}, year = {2026}, month = {03/2026}, publisher = {HamSCI}, address = {Newington, CT}, abstract = {Presented here are the results of a three-year effort to collect 6m decodes and compare these experimental results to theoretical predictions. My station, in Claremont, CA is modest: a four-element Yagi at 15 feet, 20 feet of LMR-400 cable to an Icom IC-7100 radio. Audio is fed to a notebook PC running WSJT MSK-144 software. Decodes were received from 99 stations out to 1142 miles. Daily station counts were compiled from PSK Reporter maps providing an interesting byproduct from the main study. Decode SNR{\textquoteright}s from three particularly active stations (KE4TH, W0XR and W7OUU were individually averaged. A theoretical model was created in Excel to allow for comparison with the experimental data. For the theoretical model, a sticky problem was that, in general, antenna pointing directions were not known. Thus, averaging was employed. One very cooperative station, KE4TH in Utah, provided extensive test signals with known antenna pointing thus eliminating the uncertainty due to unknown pointing. The theoretical model was based primarily on the sentinel 1997 ITU paper {\textquotedblleft}Communication By Meteor-Burst Propagation.{\textquotedblright} Another invaluable resource was the QEX paper {\textquotedblleft}The MSK144 Protocol for Meteor-Scatter Communication{\textquotedblright} by Franke and Taylor. Comparison of the theoretical predictions and the coordinated antenna data average SNR{\textquoteright}s for KE4TH yielded agreement to within about 1.5 dB. With the curve of decode probability vs. SNR (Fig. 6) in the Franke and Taylor paper, predicted signal SNR{\textquoteright}s can be converted to predicted decode probabilities, thus allowing for ms communication planning a step above just {\textquotedblleft}hoping to get lucky{\textquotedblright}. }, author = {Donald Rea} } @proceedings {1035, title = {Multi-Static HF Time Signal Analysis for Ionospheric Sounding and TEC Estimation}, year = {2026}, month = {03/2026}, publisher = {HamSCI}, address = {Newington, CT}, abstract = {This project establishes a precision HF monitoring station designed to receive 17 distinct time signal broadcasts across nine frequencies from four major national standards stations: WWV (USA), WWVH (Hawaii), CHU (Canada), and BPM (China). By utilizing a Leo Bodnar GPS-Disciplined Oscillator (GPSDO) to phase-lock the receiving hardware, the system eliminates local clock drift, ensuring that all measured timing residuals are attributable to the propagation path. The system compares these high-precision Time of Arrival (ToA) and Doppler measurements against predictions from the International Reference Ionosphere (IRI-2020) and Total Electron Content (TEC) models. The objective is to invert these residuals to solve for real-time ionospheric parameters, effectively functioning as a passive, multi-frequency oblique ionosonde.}, author = {Michael J. Hauan} } @proceedings {1014, title = {Multi-Year Climatology of Large-Scale Traveling Ionospheric Disturbances Observed with High Frequency Amateur Radio Receiving Networks Using a Novel Automated Detection Algorithm}, year = {2026}, month = {03/2026}, publisher = {HamSCI}, address = {Newington, CT}, abstract = {We present a fully automated, deterministic technique for detecting and characterizing Large Scale Traveling Ionospheric Disturbances (LSTIDs) using 14 MHz amateur (ham) radio data. The method isolates wave periods between 1{\textendash}5 hours and applies sinusoidal curve fitting to the first-hop skip-distance edge of observed communication ranges, yielding quantitative estimates of LSTID amplitude and period. Data from the Weak Signal Propagation Reporting Network (WSPRNet), the Reverse Beacon Network (RBN), and PSKReporter, which is now merged and available on the CEDAR Madrigal database, were used produce a unified multi-year climatology of LSTID activity over the continental United States (2016{\textendash}2023). Results show clear seasonal patterns: enhanced LSTID occurrence during winter, weaker activity in spring and fall, and modest summer increases. These results are consistent with prior studies and suggest modulation by neutral wind filtering, sudden stratospheric warming (SSW), vertical coupling, and solar activity.}, author = {Diego Sanchez and Mary Lou West and Nathaniel Frissell and Gareth Perry and V. Lynn Harve and Bill Engelke and Nicholas Callahan and Philip Erickso and Erich Becker and Sharon Vadas} } @proceedings {966, title = {Machine learning applied to the ray tracing model of the OTH radar}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

Over-the-horizon skywave radar (OTHR) uses reflections in the Earth{\textquoteright}s ionosphere to detect targets at very long ranges. To achieve detection, the electromagnetic energy emitted by the radar must follow a specific path with the target as its endpoint. This propagation path is strongly dependent on three factors: the direction of emission, the frequency of the electromagnetic wave and the conditions of the propagation medium, in particular the dynamic and complex characteristics of the ionosphere. From the above, it can be concluded that for this type of radar, the prior determination of the wave propagation path is essential for the correct operation of the system. In this work we are presenting the first results of a computational model based on Machine Learning to predict the propagation path of an electromagnetic wave emitted by an OTHR. A variety of ray tracing models are currently available. These models can range from very simple versions using analytical equations to versions that find the propagation path by solving a system of differential equations using numerical integration methods. The proposed model will provide solutions to the main disadvantages of traditional ray tracing models based on systems of differential equations, such as: Speed of response: once trained, the neural network model is able to respond to new queries almost instantaneously; Adaptive capability: unlike traditional models, neural networks can be retrained or adapted to incorporate new data and scenarios, improving accuracy, and, finally Reduced computing resources: optimised neural network models can run on less demanding hardware than numerical integration methods.

}, author = {Zenon Saavedra and Alexis Vale and Ana Georgina Elias} } @proceedings {951, title = {Monitoring tropospheric propagation at 24 GHz: A pilot study}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

HamSCI{\textquoteright}s upper atmosphere and space physics focus has drawn on ionospheric observations by hams using protocols including WSPR, and precision measurements of transmitters WWV and CHU with the information gathered into databases. Such techniques are applicable to other amateur radio fields to advance understanding of propagation. As an example, we describe a UK pilot system for monitoring tropospheric propagation at 24 GHz. The transmitter (JO01mt22 12 m ASL) on 24.048945 GHz has a GPS disciplined oscillator and outputs 7 W ERP to an omnidirectional antenna. Transmissions alternate each minute between WSJT-X{\textquoteright}s JT4G sub-mode and a carrier with CW identification. The 53 km test path over the Thames Estuary glances the sea surface to a receiver (JO01qj81 80 m ASL). At the receiver a masthead down-converter to 400 MHz IF connects to a Raspberry Pi controlled SDR running OpenWebRX. The pilot SDR, an RTL-dongle, is to be replaced by an Airspy R2. The data monitoring software, based on early WsprDaemon, processes WSJT-X wav files. It logs basic data of callsign, SNR and frequency from JT4G and signal and noise levels from carrier-only intervals. SNR derived from the carrier shows greater resolution and dynamic range than from JT4G. Measurements of frequency with lower scatter are obtained from cross-correlating the JT4G signal with its sync vector, finding the peaks via continuous wavelet transform then interpolation.\  Data on environment variables that may affect propagation is collected from a lightship, including air and sea temperature, relative and absolute humidity and wave height. Rain rate is from a shore station near the transmitter. Radio and environmental data go to a database with a Grafana dashboard for visualisation. Encouraging semi-quantitative effects of changes in the environment on propagation have been observed. These include: signal dropout at absolute humidity above 8 g/m3; increased variance of frequency with waveheights above 1 m; and signal level reducing gradually by 8 dB during the passage of a cold front with a band of rain up to 1 mm/hour.

}, author = {Gwyn Griffiths and John Worsnop} } @article {901, title = {Measuring height of reflection at HF}, volume = {100}, year = {2024}, month = {08/2024}, pages = {42-44}, abstract = {

Sky-wave propagation at HF relies on radio waves refracted, bent downward, back to Earth. Refraction results in a curved path within the ionosphere, but a convenient simplification is to treat the path as a reflection with a sharp apex known as the virtual height.

}, url = {https://hamsci.org/sites/default/files/publications/p42_44_Reflection_Height_RSGB_RadCom_Aug24.pdf}, author = {Griffiths, Gwyn} } @proceedings {694, title = {Measuring Daily Ionospheric Variability and the 2023 and 2024 Solar Eclipse Ionospheric Impacts Using HamSCI HF Doppler Shift Receivers}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

This project will study ionospheric variability across the continental United States (CONUS) generated by dawn/dusk transitions and two solar eclipses occurring in 2023 and 2024. Dawn and dusk produce a complex response in observed ionospheric variability that is still not completely understood. A network of Global Navigation Satellite System (GNSS) stabilized/synchronized high frequency (HF) receivers known as Grapes will be used for the study. Thirty Grape receivers will be deployed throughout North America to optimize the study of the ionospheric impacts simultaneously received from two locations. Additional stations will be funded by the HamSCI amateur radio community. This project will generate observations to answer the scientific questions: (1) How do dawn and dusk ionospheric variability vary with local time, season, latitude, longitude, frequency, distance, and direction from the transmitter? (2) Is eclipse ionospheric response symmetric with regard to the onset and recovery timing? (3) How similar is the eclipse to the daily dawn and dusk terminator passage? (4) Would multipath HF mode-splitting in the post-eclipse interval be similar to dawn events? (5) Would the response be different for two eclipses?

This project is part of the Ham Radio Science Citizen Investigation (HamSCI) program and will be open to volunteers who want to field instruments and contribute to scientific analysis and discussion. This project will also establish a new network of DASI instruments that, due to its low cost and operation by volunteers, has the potential to provide measurements for years to come. This project will support students (undergraduate, MS and Ph.D.).

}, author = {Rachel Boedicker and Nathaniel Frissell and Kristina Collins and John Gibbons and David Kazdan and Philip J. Erickson} } @article {736, title = {Measuring the Frequency Accuracy and Stability of WWV and WWVH}, volume = {107}, year = {2023}, month = {03/2023}, pages = {33-37}, abstract = {

Radio station WWV is known as a source of accurate time. However, since March 6, 1923, the original purpose of WWV has been to provide standard frequency signals, with signals broadcast in the LF and MF bands. As detailed in Hoy J. Walls{\textquoteright} {\textquotedblleft}The Standard-Frequency Set at WWV{\textquotedblright} in the October 1924 issue of QST, this
was in the early days of broadcast radio, when having an accurate frequency reference was essential for keeping stations from interfering with each other. A century later, the standard frequency signals remain essential to radio broadcasters, calibration laboratories, space weather researchers, and radio amateurs.

}, issn = {0033-4812}, author = {Michael A. Lombardi} } @proceedings {764, title = {Medium Scale Traveling Ionospheric Disturbances and their Connection to the Lower and Middle Atmosphere}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, author = {Nathaniel A. Frissell and Francis Tholley and V. Lynn Harvey and Sophie R. Phillips and Katrina Bossert and Sevag Derghazarian and Larisa Goncharenko and Richard Collins and Mary Lou West and Diego F. Sanchez and Gareth W. Perry and Robert B. Gerzoff and Philip J. Erickson and William D. Engelke and Nicholas Callahan and Lucas Underbakke and Travis Atkison and J. Michael Ruohoniemi and Joseph B. H. Baker} } @proceedings {705, title = {Modeling the Ionosphere with SAMI3 (Invited Tutorial)}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

SAMI3 (Sami3 is Also a Model of the Ionosphere) is a global, comprehensive model of the ionosphere/plasmasphere system. It is based on the SAMI2 model developed at the Naval Research Laboratory (Huba et al., 2000). SAMI3 models the plasma and chemical evolution of seven ion species (H, He, N, O, N, NO and O). The ion temperature equation is solved for three ion species (H, He and O) as well as the electron temperature equation. Ion inertia is included in the ion momentum equation for motion along the geomagnetic field. The neutral composition and temperature can be specified by empirical models (e.g, NRLMSISE00, HWM14) or by first-principle atmosphere models (e.g., TIEGCM, WACCM-X, HIAMCM). SAMI3 uses a nonorthogonal, nonuniform, fixed grid. The grid is designed to optimize the numerical mesh so that the spatial resolution decreases with increasing altitude. SAMI3 can use an untilted or tilted dipole model of earth{\textquoteright}s magnetic field, or an IGRF field model based on the Richmond apex model. A general overview of ionospheric physics and the SAMI3 model will be presented, as well as several applications of the code.

}, author = {Joseph Huba} } @proceedings {650, title = {Magnetosphere-Ionosphere Coupling Studies Using the PSWS Magnetometer Network}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

As part of HamSCI Personal Space Weather Station (PSWS) project, a low-cost, commercial off-the-shelf magnetometer, which measures magnetic field strength and direction, has been developed to provide quantitative and qualitative measurements of the geospace environment from the ground for both scientific and operational purposes at a cost that will allow for crowd-sourced data contributions. The PSWS magnetometers employ a magneto-inductive sensor technology to record three-axis magnetic field variations with a field resolution of ~6 nT at a 1 Hz sample rate. Data from the PSWS network will combine these magnetometer measurements with high frequency (HF, 3-30 MHz) radio observations to monitor large-scale current systems and ionospheric disturbances due to drivers from both space and the atmosphere. A densely-spaced magnetometer array, once established, will demonstrate their space weather monitoring capability to an unprecedented spatial extent. Magnetic field data obtained by the magnetometers installed at various locations in the US are presented and compared with the existing magnetometers nearby, demonstrating that its performance is very adequate for scientific investigations.

}, author = {Hyomin Kim and Sadaf Ansari and Julius Madey and David Witten and David Larsen and Scotty Cowling and Nathaniel Frissell and James Weygand} } @proceedings {619, title = {Mid-latitude Irregularities Observed by the Oblique Ionosonde Sounding Mode for the HamSCI Personal Space Weather Station}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

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). 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. We also investigate the dependence of the occurrence of the mid-latitude irregularities on the level of the geomagnetic activity.

}, author = {Dev Raj Joshi and Nathaniel A. Frissell and Juha Vierinen} } @proceedings {610, title = {Modeling ionograms with Deep Neural Networks: Applications to Nowcasting}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

The state parameters of the ionosphere are of fundamental importance not only for space weather studies but also for technological applications such as satellite radio communications. As with many geophysical phenomena, the ionosphere dynamics are governed by nonlinear processes that make ionospheric forecasting a challenging endeavor. However, we have enormous datasets and ubiquitous experimental sources that can help us find the complex regularities in these phenomena. We forecasted ionograms for different solar activity times and database sizes using regression deep neural networks. Due to the neural network{\textquoteright}s extrapolation of virtual heights for all frequencies given to the model, we estimated foF2 using two embedded different models to identify the last frequency of each ionogram. Furthermore, we made hyperparameter tuning for each training set applying the k-fold cross-validation method. The predictions were compared to measurements collected with the Digisonde system at the Jicamarca Radio Observatory, a persistence model, IRI, and the SAMI2 model estimations. Finally, we will present preliminary results on a new virtual heights model that predicts the difference between consecutive ionograms and preliminary results from a model to estimate electron densities.

}, author = {Jhassmin Aricoch{\'e} and Enrique Rojas and Marco Milla and Reynaldo Rojas} } @proceedings {599, title = {Moonbased Ham Repeater Station Project}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

Just as Jules Verne dreamed that man would one day reach the Moon, many radio amateurs have thought of having an amateur radio repeater on our natural satellite. Why not lay the theoretical foundations to reach this end and be able to detect the tasks to be solved? Let{\textquoteright}s try to calculate and design a repeater station and an earth station that are capable of communicating with each other and that are affordable for the average ham pocket. Today it cannot be done, but what about in 50 years?

}, author = {Carlos Mascare{\~n}as} } @proceedings {565, title = {Magnetometer Alignment Techniques Using LocalHost}, year = {2021}, month = {09/2021}, publisher = {ARRL-TAPR}, address = {Virtual}, url = {https://youtu.be/MHkz7jNynOg?t=8248}, author = {Engelke, William D.} } @proceedings {566, title = {Magnetometer Board RFI Testing (Proceedings)}, year = {2021}, month = {09/2021}, publisher = {ARRL-TAPR}, address = {Virtual}, url = {https://youtu.be/MHkz7jNynOg?t=9172}, author = {Engelke, William D.} } @proceedings {458, title = {Mid-latitude Irregularities in the Early Results from the Ionospheric Sounding Mode Using Chirp Ionosondes of Opportunity for the HamSCI Personal Space Weather Station}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

The objective of the Ham Radio Science Citizen Investigation (HamSCI) Personal Space Weather Station (PSWS) project is to develop a distributed array of ground-based multi-instrument nodes capable of remote sensing the geospace system. This system is being designed with the intention of distribution to a large number of amateur radio and citizen science observers. This will create an unprecedented opportunity to probe the ionosphere at finer resolution in both time and space as all measurements will be collected into a central database for coordinated analysis. Individual nodes are being designed to service the needs of the professional space science researcher while being cost-accessible and of interest to amateur radio operators and citizen scientists. At the heart of the HamSCI PSWS will be a high performance 1 {\textendash} 50 MHz software defined radio (SDR) with GNSS-based precision timestamping and frequency reference. This SDR is known as the TangerineSDR and is being developed by the Tucson Amateur Packet Radio (TAPR) amateur radio organization. The primary objective of PSWS system is to gather observations to understand the short term and small spatial scale ionospheric variabilities in the ionosphere-thermosphere system. These variabilities are important for understanding a variety of geophysical phenomena such as Traveling Ionospheric Disturbances (TIDs), Ionospheric absorption events, geomagnetic storms and substorms. We present early results suggesting signatures of Traveling Ionospheric Disturbances (TIDs) from an ionospheric sounding mode that we intend to implement on the PSWS system, currently implemented on an Ettus N200 Universal Software Radio Peripheral (USRP) using the open source GNU Chirpsounder data collection and analysis code.

}, author = {Dev Joshi and Nathaniel A. Frissell and William Liles and Juha Vierinen and Ethan S. Miller} } @conference {376, title = {Magnetometer Support for the Personal Space Weather Station and Related Projects}, booktitle = {HamSCI Workshop 2020}, year = {2020}, month = {03/2020}, publisher = {HamSCI}, organization = {HamSCI}, address = {Scranton, PA}, abstract = {

The Personal Space Weather Station project requires the use of a high performance, yet affordable, ground based magnetometer component. Here we describe the design and testing of a magnetometer support module for that purpose. A sufficiently cost effective magnetometer offers the opportunity to capture new science by allowing construction of large and well populated grids of instruments. The module chosen makes use of sensor components based on magneto-inductive effects. Many types of magnetometer exist, all trading cost for performance across a huge range. Our goal was to design a sensitive instrument around commercially available components that would be versatile and low enough in cost to allow its deployment in novel ways.

}, author = {D. Witten III and F. Bonte and H. Kim} } @conference {306, title = {Meteor scattering communication using JS8CALL and its possibilities}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, author = {Nagakura, Dai} } @conference {286, title = {A Modular SDR for HamSCI and Other Users}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

This presentation covers some actual hardware that can be used to fulfill the requirements of the HamSCI Personal Space Weather Station project. A new modular hardware architecture is proposed that will fulfill the requirements not only of PSWxS users, but possibly of Phase 4 Satellite Ground Station, academic research, experimenter and general SDR users as well.

}, author = {Scotty Cowling} } @conference {338, title = {Moonbounce Via the MIT Remote Linked EME Station}, booktitle = {Dayton Hamvention}, year = {2019}, month = {05/2019}, publisher = {Ham Radio 2.0}, organization = {Ham Radio 2.0}, address = {Xenia, OH}, author = {Marty Sullaway} } @conference {277, title = {Modeling Amateur Radio Soundings of the Ionospheric Response to the 2017 Great American Eclipse}, booktitle = {Fall AGU}, year = {2018}, month = {12/2018}, publisher = {American Geophysical Union Meeting}, organization = {American Geophysical Union Meeting}, address = {Washington, DC}, abstract = {

On 21 August 2017, a total solar eclipse traversed the continental United States and caused large-scale changes in ionospheric densities. These were detected as changes in medium- and high-frequency radio propagation by the Solar Eclipse QSO Party citizen science experiment organized by the Ham Radio Science Citizen Investigation (hamsci.org). This is the first eclipse-ionospheric study to make use of measurements from a citizen-operated, global-scale HF propagation network and develop tools for comparison to a physics-based model ionosphere. Eclipse effects were observed {\textpm}0.3 hr on 1.8 MHz, {\textpm}0.75 hr on 3.5 and 7 MHz, and {\textpm}1 hr on 14 MHz and are consistent with eclipse-induced ionospheric densities. Observations were simulated using the PHaRLAP raytracing toolkit in conjunction with the eclipsed SAMI3 ionospheric model. Model results suggest 1.8, 3.5, and 7 MHz refracted at h>=125 km altitude with elevation angles θ>=22{\textdegree}, while 14 MHz signals refracted at h \< 125 km with elevation angles θ \< 10{\textdegree}.

}, keywords = {Amateur Radio, Citizen Science, Ham Radio, HF propagation, ionosphere, solar eclipse}, url = {https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/418915}, author = {Frissell, N. A. and Katz, J. D. and Gunning, S. W. and Vega, J. S. and Gerrard, A. J. and Earle, G. D. and Moses, M. L. and West, M. L. and Huba, J. D. and Erickson, P. J. and Miller, E. S. and Gerzoff, R. B. and Liles, W. and Silver, H. W.} } @article {248, title = {Modeling Amateur Radio Soundings of the Ionospheric Response to the 2017 Great American Eclipse}, journal = {Geophysical Research Letters}, volume = {45}, year = {2018}, month = {05/2018}, type = {Research Letter}, abstract = {

On 21 August 2017, a total solar eclipse traversed the continental United States and caused large-scale changes in ionospheric densities. These were detected as changes in medium and high frequency radio propagation by the Solar Eclipse QSO Party (SEQP) citizen science experiment organized by the Ham Radio Science Citizen Investigation (hamsci.org). This is the first eclipse-ionospheric study to make use of measurements from a citizen-operated, global-scale HF propagation network and develop tools for comparison to a physics-based model ionosphere. Eclipse effects were observed {\textpm}0.3 hr on 1.8 MHz, {\textpm}0.75 hr on 3.5 and 7 MHz, and {\textpm}1 hr on 14 MHz and are consistent with eclipse-induced ionospheric densities. Observations were simulated using the PHaRLAP raytracing toolkit in conjunction with the eclipsed SAMI3 ionospheric model. Model results suggest 1.8, 3.5, and 7 MHz refracted at\ h >= 125 km altitude with elevation angles\ θ >= 22{\textdegree}, while 14 MHz signals refracted at\ h \< 125 km with elevation angles\ θ \< 10{\textdegree}.

}, issn = {1944-8007}, doi = {https://doi.org/10.1029/2018GL077324}, url = {https://doi.org/10.1029/2018GL077324}, author = {N. A. Frissell and J. D. Katz and S. W. Gunning and J. S. Vega and A. J. Gerrard and G. D. Earle and M. L. Moses and M. L. West and J. D. Huba and P. J. Erickson and E. S. Miller and R. B. Gerzoff and W. Liles and H. W. Silver} } @conference {221, title = {Magnetometers and Riometers}, booktitle = {HamSCI-UK}, year = {2017}, month = {10/2017}, publisher = {HamSCI-UK}, organization = {HamSCI-UK}, address = {Milton Keynes, UK}, author = {F. Honary} }