EFW Data Products/Processing
Van Allen Probe SWG
San Antonio
September 2104
J.R. Wygant, J. Bonnell, Aaron Breneman,
S. Thaller and the EFW Team
First panel is the EFW spin fit (10.5 s) electric field
in ~ dawn-dusk direction.
This measurement is dominated by waves with amplitudes
>32 mV/m ptp during during every storm as indicated by
SYM H (third panel).
The second panel is the dawn-dusk electric field averaged
over 10 minutes from both spacecraft (superposed). This
is nomally the convection electric field- but it also includes
contributions fromm injection events.
Notice the convection electric field is directed preferentially in
the positive dawn-dusk direction- the direction of sunward
convection.
Notice also the convection electric field is often peaks at
~4 mV/m which is very comparable to the magnitude of the
"solar wind electric field" (Vx sw x Bz sw). The solar wind
electric field and the measured RBSP electric fields are largest
during the main phase of geomagnetic storms and smaller
during the recovery phase.
The bottom panel shows the solar wind flow pressure and
Bmag. These typically are enhanced at the beginning of the
storm and models indicate thesubsolar magnetopause can
move within ~8-9 Re durng the intial phases of the storm when
ULF are strong. This may lead to effective radial transport
outward and loss of particles throug magnetopause
shadowing.
Towards the end of the storms, during periods of lower flow pressure,
when the estimated position of the magnetopause is outward
many storm have large wave electric fields. These are times when
relativistic fluxes increase to and often above the pre-storm levels.
includes only EFW above 3.2 Re
May- June 2013 Storms
Solar Wind Pressure
SYM-H
Ey (10 min ave) – Convection- Efield
Ey (10.5s ave) Waves/ Injection Events
Summary
ECT REPT/MagEIS Electrons
Almost all intervals of radiation belt increase or
decrease are associated with large amplitude
electric fields associated with waves 1-5 minutes
Waves at the beginning of storms are often
associated with solar wind pressure increases
that move the magnetopause close to the Earth.
These periods are aasociated with decreases.
Wave occuring after the pressure enhancements
often are associated with electron increases
Presently available on UMN EFW Website:
L2 cdfs which include:
1) Ey mgse Ez mgse spin fit resolution ( SC motional field subtracted)
2) Spacecraft potential(V1+V2)/2
3) Spectral data 30 Hz to 8 kHz: E12, Bscw
4) Filter band data peak and average (2 Hz to 8 kHz) in 7 frequency bins; two
quantities: E12 and Bscw
5) Ey mgse Ez mgse (16 Hz/ 32 samples/s)
6) SC position GSE
7) SC spin axis unit vector GSE,
8) Lvalue, MLT, MLAT
New L3 CDFs are about to be processed 1-2 weeks:
1) Ey mgse Ez mgse in the Earths corotational frame
2) Density
3) All information above
EFW burst data 3 E, 3 Bsc, V1-V6 is posted on a UCB SSL website. It is
EFW burst data is posted on a UCB SSL website.
• The TDAS software to convert this to L-2, L3 version scientific data
products (mgse, GSE coordinate system; spectograms, convolution over
gain-phase response functions etc) is available to the scientific community
and has been described in numerous data access workshops at GEM and
AGU.
The burst data consists of :
• 3 components of the E-field in rotating SC frame
• 3 components of the search coil B-field
• V1-V6 Single probe measurements.
• The files for these playback are often quite large: 6 quantities x 16.4
ksamples/s for 30 minutes to 5 hours. They are collected during active
periods and are intermittent.
• It can take hours to transfer these files over the internet and many
computers do not have sufficient memory to process them.
• It would be quite difficult for the cdaweb to assimilate this data.
The EFW team has also posted survey plots which can be viewed on the UMN
EFW website and also downloaded as pdf files.
These plots contain the L2 version quantities described in the previous slide
plus information on spacecraft relative positions.