The Mid- and Low-Latitudes
Ionospheric Phenomena:
Potential Challenge to our
Technological Systems
Endawoke Yizengaw
ISR, Boston College
Outline
 SED/plume signatures at different longitudinal
sectors
 SED/Plume driving force (electrodynamics)
longitudinal difference
 Is the vertical drift a prime candidate for
initiating the RT-instability?
 What cause the post-midnight bubbles,
especially during magnetically quiet period?
 Fun time! (personal experience from my recent
scientific mission in Africa and Chile)
Storm Enhanced Density plume Background
 SED was identified, for the first time, in early 1990’s using ISR
observation at MH-ISR
 Characterized by high TEC values, strong gradient, and high
ion flux tube
 According to the comparison between GPS TEC and ISR TEC
measurement, ~50% of SED/TEC is from higher than 800 km
 Observed in the dusk sector over the American sector during
geomagnetic storm period.
 SED/TEC plume correlates well with plasmaspheric drainage
plume observed by IMAGE EUV.
Foster et al., GRL, 2002
SAPS
SAPS
How does SAPS formed??
SAPS: Plasmaspheric driving force
 Corotational E-field (produced
in the ionospheric E-layer and
conveyed
into
the
plasmasphere along the Bfield), which is weak.
 Convection E-field (applied to
the magnetosphere by its
interaction with the solar wind),
which is large.
SAPS: Plasmaspheric driving force
 The two then superimposed and form SAPS E-field that
creates a drift pattern, forming plasmaspheric plume.
IMAGE EUV
SAPS effect on the ionosphere
How does this come
down to the ionosphere?
R1
R2
LOW Σ
SAPS E Field
Where does the storm
enhanced density (SED)
then came from?
(after J. Goldstein)
Where did such enhanced
density came from?
(Mannucci et al., 2005)
Electrodynamics and SAPS
combined effect on the ionosphere
E B
B
, g
E

, g
Such density gradient is a
problem for navigation,
primarily for WAAS
system.
Equator
SAPS
N
S
TEC Hole
Foster et al., GRL, 2002 Modified after J. Foster
Recent
observation of
the SED plume
evolution
Courtesy to C. Valladares
Does it occur in any other longitudinal sector?
SED/Plume over Europe/Atlantic
Madrigal TEC database
TOPEX pass
DMSP F15
Yizengaw et al., JGR, 2008
Plasmapause
position from
IMAGE EUV
SED/Plume over Europe
Coster et al., GRL, 2007
SED/Plume over Asia
Madrigal TEC
database
Over Atlantic Ocean
Yizengaw et al., JGR, 2008
SED/Plume statistical survey
 31 distinct
plasmaspheric
plumes observed
in the first half
of 2001
12 12
10
9
 12 over NA, 9
over Europe,
and 10 over Asia
4
2
 Only 18 SED/plume observed
 12 over NA, 4
over Europe,
and 2 over Asia
Yizengaw et al., JGR, 2008
SED/Plume statistical survey (cont.)
 The maximum TEC value
at the SED plume base,
showing higher value over
the
American
sector
compare to European and
Asian sector.
European sector
American sector
Coster et al., GRL, 2007
 The location of plume base
latitudinal
difference,
indicating the SED/TEC
plume occurs at higher
latitudes in the European
and Asian sector.
Some note about SED plume
 The plumes signature can be observed at any
longitudinal sector, potentially contributing to the
degradation of our communication and navigation
systems around the globe.
 SED/TEC plume occurrence probability difference
could be due to at least two reasons.
1. SED/TEC plume is very weak, due to weak vertical
drift in the African and Asian sectors, and difficult to
detect with the few GPS receivers in the region.
2. The geomagnetic equator position difference at different
longitudinal sector, placing the plume at higher latitudes
in the European and Asian sector
How about the longitudinal variability of electrodynamics?
Longitudinal Electrodynamics Variability
 Disturbances due to
geomagnetic impact
On H-components at
the equator and off the
equator
 Disturbances due to
EEJ
Only on H-component
at the equator
Validating with other observations
with JULIA
C/NOFS - Africa
Longitudinal EEJ Variations
77°W 69°W 56°W 8°E
Yizengaw et al., AG, 2013 (submitted)
77°W
56°W 8°E 38°E
Longitudinal drift Variations
IVM drift average (2009-2013)
Mlat = ±8° of the geom. equator
Lon = ±3.5 of the given meridian
Alt: = < 500km
Incl.: 13°
Alt.: 400 – 850km
Instruments: PLP, IVM,
VEFI, magnetometer, GPS,
and lightening detector
The drift in general
decrease in magnitude as
we go east.
Yizengaw et al., AG, 2013 (submitted)
What cause the enhancement of
Rayleigh-Taylor instability growth rate?
Then why the bubble distributions
show the other way around?
Hei et al., 2005
Courtesy of Odile
Then why the bubbles’ distribution
show the other way around?
Fall
PA AM
AF
Fall
Fall
Su, 2006
Hei et al., 2005
IN
Then why the bubbles’ distribution
show the other way around?
DMSP Observations:
Gentile et al., 2011
In Africa (Long ~ -20 to
52) dusk sector irregularities
are active almost all seasons
during solar max.
C/NOFS Observations
Yizengaw et al.
Longitudinal variability of bubbles
Bubble detection technique from
the ground-based observations
Dusk sector (1900 – 2400 LT)
Dawn sector (0000 – 0500 LT)
Longitudinal variability of bubbles & Scintillation
Dusk sector (1900 – 2400 LT)
S4 index (1800 – 2400 LT)
360
Bubbles from
ground-based
GPS TEC
300
240
180
120
60
360
300
240
180
120
60
S4 index from
ground-based
GPS TEC
S4 index: 2010
360
300
240
180
120
60
S4 index: 2011
S4 index: 2012
Longitudinal variability of bubbles & Scintillation
Dawn sector (0000 – 0500 LT)
S4 index (0000 – 0500 LT)
360
Bubbles from
ground-based
GPS TEC
S4 index: 2010
300
240
180
120
60
360
300
240
S4 index: 2011
TEC depth
180
120
60
S4 index from
ground-based
GPS TEC
360
300
240
180
120
60
S4 index: 2012
Potential questions?
 If the drift is weaker in the African sector, what
causes these strong bubbles that have been
observed in the African sector almost throughout
the night and during all seasons? Are there other
mechanisms that initiate RTI growth rate other
than vertical drift?
 If not the drift, then what could it be? Would it be
the neutral winds that cause the long lasting
bubbles in Africa? If it is the neutral wind, why are
the winds unique in terms of orientation and
magnitude in the African sector compared to other
longitudinal sectors?
What cause the post-midnight
bubbles and scintillation,
especially during magnetically
quiet periods
Quiet time post-midnight ionosphere irregularities
Yizengaw et al., GRL, 2013 (in press)
Quiet time post-midnight ionosphere
irregularities (Statistics from C/NOFS)
We use dN/N parameter as proxy for bubble occurrence
There is wide
bubble but dN/N
did not detect it
Quiet time post-midnight bubbles Occurrence
distribution
Yizengaw et al., GRL, 2013 (in press)
What cause these quiet time post-midnight bubbles?
Is there RT instability during this local time?
PBMOD run
growth rate
6hrs
4hrs
3hs
2hrs
1hrs
RT
instability
What cause the vertical drift
velocity to be reversed at this
local time sector and during quiet
periods?
Sporadic E-layer presence? If so
what is the primary mechanism
for the formation of Es layer?
(1) Charged dust particles due to
strong gusty winds, (2) meteors
that can cause ionization, (3)
polarized
electric
field
associated with the MSTID
Yizengaw et al., GRL, 2013 (in press)
Ongoing expansion of AMBER networks
Team Members: E. Yizengaw (BC, PI); M. Moldwin (UM); E. Zesta
(NASA); M. Magoun (BC); K. Hector (UCLA); SCINDA team?
Upcoming iMAGs (SAMBA-AMBER-MEASURE)
Team Members: M. Moldwin (UM, PI); E. Yizengaw (BC, PI); E. Zesta
(NASA); A. Boudouridis (SSI); M. Magoun (BC); K. Hector (UCLA)
Our Magnetometer Database
Some of iMAGs objectives
 To understand the structure and dynamics of plasmaspheric mass
and number density, and to contineously monitor the
plasmapause location
 Field Line Resonances (FLR)
 Identify the plasmapause location from spectral cross-phase
reversal of two mag. stations and using GPS TEC and
Tomography Technique
 Remotely monitoring the plasmasphere boundary layer location.
Key input for radiation belt acceleration.
 To continue filling the gaps of equatorial region and study EEJ
dynamics and the penetrating ULF waves and its possible
relationship to scintillation at different longitudes.
 Investigating the connection between ULF waves and
scintillation using combination of mag. and GPS observations
 To understand the interhemispheric asymmetries of ULF wave
power and the state of the ionosphere
Mission in Conakry, Guinea!
Welcome to Guinea
Start the mission
Effort to put GPS antenna
Partial accomplishment
Diplomacy is very important
Training kicked off
Mission in Conakry, Guinea!
Sometimes politician
get interested in
science. How
important is that?
Scientific briefing
Can I see what you briefed me?
Ops! Face the consequence (next day he came with TV crew)
Sometimes you get this!
Mission in Abidjan, Ivory Coast!
Compete renovation
The 2011 riot damage
SCINDA GPS was? Empty MAGDAS site
Site identified but the mag still in custody
Mission in Abidjan, Ivory Coast!
Guantanamo bay of my mag!
After 6hrs back and forth diplomacy!
Worked very hard to compensate the time we spent at custody!
Multiple Mission in Chile
MI-coupling meeting at Torres Del Paine National Park!
The Second SAMBA-iMAGs workshop in Punta Arenas
Multiple Mission in Chile
The new home for our magnetometer!
Excavate the sensor carefully from here!
At its new home!
Bangkok, Thailand is the next stop!
http://endawokeonscientificmission.blogspot.com/
Thank you!