Climatology of Traveling Ionospheric Disturbances Observed by HamSCI
Amateur Radio with Connections to Geospace and Neutral Atmospheric
Sources.
Abstract
Traveling Ionospheric 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 ≈30-180 min, horizontal phase velocities
vH≈100-250 m/s, and horizontal wavelengths 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). In this study, members of the Ham
Radio Science Citizen Investigation (HamSCI) 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’s
Modern-Era Retrospective Analysis for Research and Applications Version
2 (MERRA-2).