The Location and Evolution of the
South Atlantic Anomaly as Observed
by SOLSTICE
Laura O’Connor (University of Michigan)
Mentor: Marty Snow (Laboratory for Atmospheric and Space Physics)
Outline
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Background information
Description of the region of interest
Motivation for the project
Introduction to the SOLSTICE Instruments
Details of the SOLSTICE Data
Data analysis procedures
Future plans
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details June 2011 Future Plans
Background
Van Allen Radiation Belt Diagram
Image Credit: http://www-spof.gsfc.nasa.gov
/Education/Iradbelt.html
2011 REU in Solar and Space Physics
• Van Allen Radiation Belt
discovered in 1958
• Three modes of motion: rotation
around the magnetic field lines,
drift, bounce
• Mirroring is determined by the
strength of the magnetic field
(which is increasingly stronger
closer to the Earth’s surface)
Outline The SAA SOLSTICE Data Details June 2011 Future Plans
Background
• Region Of Study: South
Atlantic Anomaly (SAA)
• SAA is a part of the Van Allen
radiation belt
• Caused by an offset of the
Earth’s magnetic field
• Sources say the SAA is moving
by 0.28 degrees/year
westward and 0.08
degrees/year northward
2011 REU in Solar and Space Physics
Radiation Belts
Image Credit: Introduction to the Space Environment by
Thomas F. Tascione
Outline The SAA SOLSTICE Data Details June 2011 Future Plans
Motivation
• All satellites in low Earth orbit are influenced by the South
Atlantic Anomaly
• Instruments and other electronics aboard can be susceptible
to the regions high radiation
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details June 2011 Future Plans
Introduction to SOLSTICE
• SOLSTICE: SOLar STellar Irradiance
Comparison Experiment
• There have been two SOLSTICE
experiments, one aboard UARS (19912005, 600km) and one aboard SORCE
(2003-Present, 645km)
• Each SOLSTICE on SORCE is made up of
two Instruments: A (primary mode:
Middle Ultraviolet) and B (primary
mode: Far Ultraviolet)
• SOLSTICE observes the Sun, 18 stars,
dark regions of space
2011 REU in Solar and Space Physics
SORCE Spacecraft
Image Credit: http://lasp.colorado.edu
/sorce/index.htm
Outline The SAA SOLSTICE Data Details June 2011 Future Plans
Introduction to SOLSTICE
MUV Detector
FUV Detector
SOLSTICE Instrument aboard SORCE
Image Credit: http://lasp.colorado.edu/sorce/index.htm
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details June 2011 Future Plans
Data Details
• There are two types of data available from SOLSTICE
– Inactive Channel Data: SOLSTICE A (FUV Detector) and
SOLSTICE B (MUV Detector) from February 4, 2003 to
July 1, 2011
– Stellar Dark Region Data: SOLSTICE A (FUV Detector)
and SOLSTICE B (MUV Detector) dark region data from
February 22, 2003 to July 01, 2011
• Primary data for this study: Inactive channel data for the
SOLSTICE A FUV Detector
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Data Details
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Data Details
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Data Analysis
Data Collection and Organization
Selection of Count Rate Data in 5 Day Intervals
Conversion to Geomagnetic Coordinates
Average All Data in 5 Day Interval into 1x1 Degree Bins
End Result: 360x180 Data Array
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Data Analysis
Select 1° Latitude Strip
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Data Analysis
Fit Gaussian To Latitude Strip
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Data Analysis
Fit 2nd Gaussian To Peaks
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Data Analysis
Latitude Extent
Center of SAA
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Results
Longitude (Degrees)
Center of SAA: Longitude
30
y = -0.3283x + 25.566
28
26
24
22
20
0
1
2
3
4
5
6
7
8
9
8
9
Time Since 2003 (Years)
Center of SAA: Latitude
Latitude (Degrees)
-12
y = 0.1602x - 18.183
-14
-16
-18
-20
-22
0
1
2
3
4
5
6
7
Time Since 2003 (Years)
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details June 2011
Future Plans
UARS
• UARS SOLSTICE (19912005): Stellar Dark Rate
Data
• Extends time of study
through two decades
• No Inactive Channel
UARS Spacecraft
Image Credit: http://umpgal.gsfc.nasa.gov/
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details June 2011
Future Plans
UARS
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details June 2011
Future Plans
UARS
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details June 2011
Future Plans
Results With UARS
Longitude (Degrees)
Center of SAA: Longitude
35
30
25
20
15
10
5
0
y = -0.2997x + 626.14
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
Years
Center of SAA: Latitude
Latitude (Degrees)
0
-5
y = -0.0705x + 124.46
-10
-15
-20
-25
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
Years
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Future Directions
Magnetic Field Strength at Vassouras
23650
23600
23550
Field Strength (nT)
y = -18.389x + 60258
23500
23450
23400
23350
23300
23250
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
Years
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Future Directions
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Future Directions
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Future Directions
Longitude Extent (Degrees)
Longitude Extent
20
y = 1.0347x - 2062.8
15
10
5
0
-5
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2004
2006
2008
2010
2012
Years
Latitude Extent (Degrees)
Latitude Extent
8
7.5
7
6.5
6
5.5
5
1992
y = 0.1358x - 265.6
1994
1996
1998
2000
2002
Years
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Future Directions
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Future Directions
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Future Directions
• Possible correlation between SAA and geomagnetic
storms
• Time Lag – radiation in the belts takes a while to build up
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
Conclusions
• The SAA is moving at a rate of 0.3283 degrees/year
westward and 0.1602 degrees/year northward
• The SAA is increasing in extent by 0.1358 degrees/year in
latitude and by 1.0347 degrees/year in longitude, when data
from UARS is included in the calculation
• There are possible correlations, to be examined more
closely, between the South Atlantic Anomaly and
geomagnetic activity, solar cycle and the weakening of
the Earth’s magnetic field.
2011 REU in Solar and Space Physics
Outline The SAA SOLSTICE Data Details
June 2011 Future Plans
THANK YOU
Any Questions?
References
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Image Credit: http://chamorrobible.org/gpw/gpw-200911.htm
Image Credit: http://lasp.colorado.edu/sorce/index.htm
“Introduction to the Space Environment”, Thomas F. Tascione, Orbit Foundation
Serie
sTrivedi, N.B., Pathan, B.M., Schuch, Nelson J., Barreto, M., Dutra, L.G.
“Geomagnetcic phenomena in the South Atlantic anomaly region in Brazil”, Adv. in
Space Res., 36 (2005) 2021-2024
Badhwar, Gautam D., “Drift rate of the South Atlantic Anomaly”. Journal of
Geophysical Research, vol. 102, no. A2, pp. 2343-2349, 1997
doi:10.1029/96JA03494
2011 REU in Solar and Space Physics
References Backup Slides