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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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.)