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Experiment Design
Experiment Design to Assess Ionospheric Perturbations During a Solar EclipseMagdalina Mosesab, Dr. Gregory Earlea, Nathaniel Frissella
Department of Electrical and Computer Engineeringa, Department of Mathematicsb
Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061
On August 21, 2017 there will be a total solar eclipse over the United States traveling
from Oregon to South Carolina. Solar eclipses offer a way to study the dependence of
the ionospheric density and morphology on incident solar radiation. There are
significant differences between the conditions during a solar eclipse and the
conditions normally experienced at sunset and sunrise, including the east-west
motion of the eclipse terminator, the speed of the transition, and the continued
visibility of the corona throughout the eclipse interval. Taken together, these factors
imply that unique ionospheric responses may be witnessed during eclipses. These
may include changes in the ionospheric electric fields, changes in the Total Electron
Content (TEC) along paths through the eclipsed region, and variations in the density
and altitude of the F2 peak. The overall objectives of this study are to characterize
these changes in F-region plasma morphology during the eclipse over a larger spatial
domain than any previous eclipse experiment. This will be accomplished using a
nationwide network of GPS receivers, as well as a coherent scatter radar and a
variety of techniques involving amateur radio.
Abstract
Introduction
[1] The Exploratorium, "2008 Solar Eclipse at Totality,"
265510main_aug1totality1_full_full.jpg, Ed., ed: NASA, 2008.
[2] M. Anastassiades, "Solar Eclipses and the Ionosphere," in A NATO Advanced
Studies Institute, Lagonissi, Greece, 1970.
[3] H. Rishbeth and O. K. Garriott, Introduction to Ionospheric Physics. New York;
San Francisco; London: Academic Press Inc. , 1969.
[4] E. L. Afraimovich, E. A. Kosogorov, and9 O. S. Lesyuta, "Effects of the August
11, 1999 total solar eclipse as deduced from total electron content measurements
at the GPS network," Journal of Atmospheric and Solar-Terrestrial Physics, vol. 64,
pp. 1933-1941, 12/2002
[5] N. A. Frissell, E. S. Miller, S. R. Kaeppler, F. Ceglia, D. Pascoe, N. Sinanis, et al.,
"Ionospheric Sounding Using Real-Time Amateur Radio Reporting Networks,"
Space Weather, vol. 12, pp. 651-656, 2014.
The 2017 solar eclipse covers a very long longitudinal path over the US - it is
unmatched by any eclipse over the US in the past 60 and in the next 30 years.
The development of professional networks across the US, such as the CORS
network, as well as the advent of amateur radio reporting networks have
enhanced the spatial resolution of our data collection relative to previous
studies. These factors create an unprecedented opportunity for data collection
over a much larger area than has previously been possible during an eclipse.
Observations of the ionosphere under the solar eclipse’s unique conditions
should allow for high resolution observations of the processes taking place in the
ionosphere. Comparison with models may provide additional insight into the
production, loss, and diffusive transport processes operating in the ionosphere.
Modeling and data assimilation tools for this study will be developed throughout
2016, in preparation for the 2017 eclipse.
The objective of this experiment is to learn as much as possible about the
changes in the density structure during the eclipse and the spatial extent of the
eclipse’s effects on the ionosphere. This will be achieved by combining and
analyzing information from the data sources outlined in Table 1.
-David Eagle: “A MATLAB Script for Predicting Solar Eclipses”-code used to find the
start time of the penumbral phase of 2017 eclipse
-Fred Espenak: “Path of the Total Solar Eclipse of 2017 Aug 21”
-Dr. Wayne Scales and Matt Shoemaker at Space@VT for GPS work
-Dave Pascoe, Deven Chheda, and Carson Squibb for RBN support
Acknowledgements
References
Conclusions and Discussion
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17:02:24 17:31:12 18:00:00 18:28:48 18:57:36 19:26:24 19:55:12
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E Region Electron Density over the Course of the Eclipse as a Percent of Uneclipsed Electron Density
%Electron Density Depletion
Uneclipsed Percent of Sun
Figure 2. Eclipse effects on E
Region electron density
The map above shows that the 2017 eclipse will have a longer path over the
continental US than any eclipse in the last 60 years.
Figure 1. US Solar Eclipse Map
Initiative Ground Coverage Operations Concept
RBN(Reverse Beacon Network)
Nationwide passive amateur
radio reporting network
Receive and record Morse code
and digital signals on multiple
frequencies simultaneously
Eclipse QSO PartyA nationwide amateur radio
operating event
Operators make contact with as
many stations as possible over the
course of the eclipse
Rules used to generate the
necessary data
VTARA(Virginia Tech Amateur
Radio Association)
Around 3-5 teams
positioned at different
locations along the eclipse
path.
Participate in Eclipse QSO Party
with a well-defined operation mode
Stay on frequencies that most
amateur radio operators would not
transmit on during an eclipse QSO
party
WSPRNet(Weak Signal Propagation
Reporting Network)
Nationwide active amateur
radio network
WSPRNet operators transmit and
receive over the course of the
eclipse
CORS(Continuously Operating
Reference Station)
GPS receiver network
spread across the US
Receive GPS satellites’ signals that
travel through the ionosphere in the
eclipse path
SuperDARN(Super Dual Auroral Radar
Network)
Three locations:
Blackstone, VA
Fort Hays, KS
Christmas Valley, OR
Observe changes as the eclipse is
incoming and outgoing
Preliminary Models
Solar eclipses offer an opportunity to
determine the dependence of the
ionosphere on sunlight[2]. Electron
density is highly dependent on solar
radiation; thus, a change in electron
density can be expected[2].
Our preliminary model (Fig. 2) of the solar
eclipse’s effect on the electron density in
the E layer support this hypothesis.
Historical Observations
Since the early-to-mid 1900s, researchers
have conducted experiments to observe
ionospheric phenomena that arise as an
effect of an eclipse.
The plot of Britain’s Chilton ionosonde’s
foF2 data during the August 1999 eclipse
(Fig. 3) shows a distinct decrease in foF2
at the onset of the eclipse (with totality at
about 1000LT). This decrease is a distinct
deviation from the IRI model for that date.
Past results are inconsistent – eclipses
have ionospheric effects that are affected
by magnetic latitude.
Ionospheric Implications
Figure 3. Effect of the August 11,
1999 eclipse on foF2 [4]
Our proposed experiment includes several initiatives and networks, outlined in the
table below, to generate and collect data on the changes in radio propagation over the
course of the eclipse. As illustrated, the experiment includes standard ionospheric
sounding techniques including the Continuously Operating Reference Station (CORS)
GPS receivers and SuperDARN radars as well as various amateur radio networks.
Amateur Radio Ionospheric Sounding
Table 1. Propagation Path Diagnostics
Recent advances in the fields of computing, software defined radio, and signal processing
provide unprecedented opportunities for space science investigations assisted by amateur
radio operators. These opportunities are beginning to be realized with the advent of networks
of amateur radio reporting systems such as the Reverse Beacon Network (RBN) and the
Weak Signal Propagation Reporting Network (WSPRNet) [5].
(cont.) show a decrease in the number of stations the RBN heard on the dayside,
associated with the arrival of a solar flare. Hence, the RBN has the ability to detect
space weather events over large areas and, with the development of the proper
data analysis techniques, more quantitative data could be derived from this system.
Eclipse QSO Party
One of the times of intense amateur radio operation is during a contest or other
special operating event such as a QSO Party. A QSO is a contact over the radio,
hence, a QSO party is a formal amateur radio operating event where operators
try to make and log as many contacts as possible in a set amount of time and in
a manner consistent with the particular QSO party’s rules.
The eclipse QSO party has three goals: to get people on the air to generate
signals for the RBN, to generate data in the logs submitted by operators after the
event, and to engage the public in a scientific investigation of the eclipse.
Virginia Tech Amateur Radio Association (VTARA)
VTARA’s effort will fill in potential gaps in the QSO party data by generating
activity on frequencies that may not be the best for making the most QSOs.
Figure 4. RBN Response to X Class Solar Flare
Reverse Beacon Network
The RBN is an amateur radio
reporting system comprising of a
network of automated receiving
stations designed primarily to
facilitate the needs of amateur
radio contesters. These stations
scan and decode portions of the
radio frequency spectrum for
Morse code and some digital
signals.
For every transmission received,
the RBN stations report: the
callsign heard, the time, the
mode, the frequency, and the
signal-to-noise ratio. All of this
data is archived and made
publically available on the RBN
website.
This network has enormous
potential for ionospheric research
[5]. The maps on the right (cont.)