@article{df8aa84e6c184a47b544905c3eb1651d,
title = "High-Frequency Communications Response to Solar Activity in September 2017 as Observed by Amateur Radio Networks",
abstract = " Numerous solar flares and coronal mass ejection-induced interplanetary shocks associated with solar active region AR12673 caused disturbances to terrestrial high-frequency (HF, 3–30 MHz) radio communications from 4–14 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 Kp max = 8+ and SYM-H min = −146 nT occurring 7–10 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.",
keywords = "HF radio propagation, amateur radio, geomagnetic storm, ham radio, radio blackout, solar flare",
author = "Nathaniel Frissell and Vega, {Joshua S.} and Evan Markowitz and Andrew Gerrard and Engelke, {William D.} and Erickson, {Philip J.} and Miller, {Ethan S.} and Luetzelschwab, {R. Carl} and Jacob Bortnik",
note = "Funding Information: N. A. F. acknowledges the support of NSF Grant AGS-1552188/479505 -19C75. We are especially grateful to the amateur radio community who voluntarily produced and provided the HF radio observations used in this paper, especially the operators of the Reverse Beacon Network (RBN, reversebeacon.net), the Weak Signal Propagation Reporting Network (WSPRNet, wsprnet.org), qrz.com, and hamcall.net. September 2017 amateur radio data used in this paper are available from https://doi.org/10.5281/ zenodo.1489370; other amateur radio data are available from the source websites listed above. The Kp index was accessed through the OMNI database at the NASA Space Physics Data Facility (https://omniweb.gsfc. nasa.gov/). The SYM-H index was obtained from the Kyoto World Data Center for Geomagnetism (http://wdc. kugi.kyoto-u.ac.jp/). GOES data are provided by NOAA NCEI (https:// satdat.ngdc.noaa.gov/). GPS-based total electron content observations and the Madrigal distributed data system are provided to the community as part of the Millstone Hill Geospace Facility by MIT Haystack Observatory under NSF grant AGS-1762141 to the Massachusetts Institute of Technology. The authors wish to thank the World Wide Lightning Location Network (http://wwlln.net), a collaboration among over 50 universities and institutions, for providing the lightning location data used in this paper. We acknowledge the use of the Free Open Source Software projects used in this analysis: Ubuntu Linux, python (van Rossum, 1995), matplotlib (Hunter, 2007), NumPy (Oliphant, 2007), SciPy (Jones et al., 2001), pandas (McKinney, 2010), xarray (Hoyer & Hamman, 2017), iPython (P{\'e}rez & Granger, 2007), and others (e.g., Millman & Aivazis, 2011). N. A. F. thanks Robert Redmon, Delores Knipp, Hyomin Kim, and Rachel Frissell for helpful discussions. Funding Information: N.?A.?F. acknowledges the support of NSF Grant AGS-1552188/479505-19C75. We are especially grateful to the amateur radio community who voluntarily produced and provided the HF radio observations used in this paper, especially the operators of the Reverse Beacon Network (RBN, reversebeacon.net), the Weak Signal Propagation Reporting Network (WSPRNet, wsprnet.org), qrz.com, and hamcall.net. September 2017 amateur radio data used in this paper are available from https://doi.org/10.5281/zenodo.1489370; other amateur radio data are available from the source websites listed above. The Kp index was accessed through the OMNI database at the NASA Space Physics Data Facility (https://omniweb.gsfc.nasa.gov/). The SYM-H index was obtained from the Kyoto World Data Center for Geomagnetism (http://wdc.kugi.kyoto-u.ac.jp/). GOES data are provided by NOAA NCEI (https://satdat.ngdc.noaa.gov/). GPS-based total electron content observations and the Madrigal distributed data system are provided to the community as part of the Millstone Hill Geospace Facility by MIT Haystack Observatory under NSF grant AGS-1762141 to the Massachusetts Institute of Technology. The authors wish to thank the World Wide Lightning Location Network (http://wwlln.net), a collaboration among over 50 universities and institutions, for providing the lightning location data used in this paper. We acknowledge the use of the Free Open Source Software projects used in this analysis: Ubuntu Linux, python (van Rossum,), matplotlib (Hunter,), NumPy (Oliphant,), SciPy (Jones et al.,), pandas (McKinney,), xarray (Hoyer & Hamman,), iPython (P?rez & Granger,), and others (e.g., Millman & Aivazis,). N.?A.?F. thanks Robert Redmon, Delores Knipp, Hyomin Kim, and Rachel Frissell for helpful discussions. Publisher Copyright: {\textcopyright}2019. The Authors.",
year = "2019",
month = jan,
doi = "10.1029/2018SW002008",
language = "English (US)",
volume = "17",
pages = "118--132",
journal = "Space Weather",
issn = "1542-7390",
publisher = "American Geophysical Union",
number = "1",
}