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Mona KesselOn detail at NASA GSFC
missions and observablespast, present, and future
Measuring Magnetosphericvariability
Ground-based
Space-based
Early Space ExplorationSputnik, October 1957
Explorer 1, January 1958 – First Discovery of the Space Age: Earth’s radiation beltsExplorer 2, 3, 4. Pioneer 1, 2, 3, ..
Exploration of the 1960’s
ATS 1-6 testing concepts in spacecraft design, propulsion, and stabilization, communication systemsDiscoverer 17 USAF photographic surveillance satellite assessing Soviet capabilities
Pioneer 6, 7, 8, 9Solar wind and magnetic field mapping in interplanetary spaceCosmic ray measurements and solar particle studies
COSMOS 2-261, Electron 1-4, Soviet satellites to study radiation belts, ionosphere, aurora
Explorer 5-35, study trapped radiation, ion and electron density & temperature, solar x-rayExplorer 15, study artificial radiation belt produced by Starfish high-altitude nuclear burst July 1962
Van Allen’s plot of Explorer 3 data in a hotel room on April 3, 1958
Explorer spacecraft made possible early studies of the radiation belts
Space Exploration 1970’s & 1980’s1973 IMP-8 measured magnetic fields, plasmas, energetic charged particles (e.g., cosmic rays) of Earth's magnetotail and magnetosheath and of the near-Earth solar wind. IMP operated 33 years in its 35 Earth Radii, 12-day orbit.
1975 GOES series of satellites measuring magnetic fields and particles in geosynchronous orbit, latest one in operation today.
1977 ISEE 1,2 investigate outermost boundaries of the Earth's magnetosphere, examine structure of solar wind near Earth and shock wave upstream, investigate cosmic rays and solar flare effects.
1978 ISEE 3 daughter of ISEE 1 with same goals as ISEE 1,2(1982 ICE) investigate magnetotail and conduct comet encounter
1981 DE investigated coupling between hot, tenuous, convecting plasmas of the magnetosphere and the cooler, denser plasmas and gases corotating in the earth's ionosphere, upper atmosphere, and plasmasphere.
1984 AMPTE CCE/UKS/IRM studied the access of solar-wind ions to the magnetosphere with lithium and barium tracer ions, 3 satellites to help distinguish between spatial structure and temporal changes.
1970’s Pioneer 10, 11, Voyager 1, 2 to Jupiter, Saturn and beyond.
IMP-8
ISEE-3
Voyager-1For more information go to http://nssdc.gsfc.nasa.gov/nmc/SpacecraftQuery.jsp
Earth
SUN
BowShock
IMP-8 spacecraft orbited around the Earth measuring fields and particles
Magnetopause
Start
Finish
Magnetic field magnitude
Bulk ion speed
Bulk ion density
B
V
N
August 1985
Bow Shock Magnetopause
Day 221 = Aug 9
No particles?
No particles?
IMP-8 made possible early studies around the magnetosphere
http://www-pi.physics.uiowa.edu/imp-data/
Low Energy Proton and Electron Differential Energy Analyzer (LEPEDEA) Spectrograms16 energy intervals between 5 eV and 50 keV. They had an angular field of view of 9° x 25°
Current Era Space Exploration
Geotail
CRRES
CRRES
Geotail
IMAGE
Cluster
THEMISTWINS
RBSPMMS
What are the magnetospheric obervables?
• Magnetic Field
• Electric Field
• Ions
• Electrons
• Neutrals
Background/guiding fields;Waves - broad frequency range
Bulk parameters: density, speed, temperature;Counts/flux across broad energy range
• Photons Visible, UV, EUV, FUV
Space-based Ground-based
• Magnetic Field
Background fieldLow frequency waves
• Photons All Sky images
• Radars Ionospheric convection
from Russell, C., “The Magnetosphere,” in The Solar Wind and the Earth, eds. S. -I. Akasofu, Y. Kamide, pp. 73-100, Terra Scientific Publishing Company, Tokyo, 1987.)
The basic features of the Earth’s magnetosphere
X
Z
& Radiation Belts& Ring Current
from Russell, C., “The Magnetosphere,” in The Solar Wind and the Earth, eds. S. -I. Akasofu, Y. Kamide, pp. 73-100, Terra Scientific Publishing Company, Tokyo, 1987.)
The basic features of the Earth’s magnetosphere
1
2
3
4
5
6
X
Z
& Radiation Belts& Ring Current
Cluster spacecraft made possible studies of the solar wind and bow shock.
Earth’s quasi-perpendicular shock is very thin.
& Radiation Belts
1
Cluster satellites
X
ZProton Density
Proton Speed (VX)
Proton Speed (Vy)
Proton Speed (Vz)
Magnetic Field
Electron Density
& Radiation Belts& Ring Current
1
1b
X
Y
Artists’s conception of Earth’s
bow shock
1b
Cluster satellites
X
Z Proton Density
Proton Speed (VX)
Proton Speed (Vy)
Proton Speed (Vz)
Magnetic Field
Electron Density
Earth’s quasi-parallel shock is thick and turbulent.
Cluster spacecraft made possible studies of the solar wind and bow shock.
& Radiation Belts& Ring Current
2
ISEE made possible the study of the internal structure of the magnetopause.
Earth’s magnetopause is thick and multi-layered
& Radiation Belts& Ring Current
Courtesy J. Dorelli
3X
Z
Earth’s aurora is a window into MI coupling
Polar’s view of auroral oval marks the boundary between open and closed field lines.
& Radiation Belts& Ring Current
4
X
Z
Earth’s magnetotail stores and releases energy.
& Radiation Belts& Ring Current
IMP-8 spacecraft made possible studies of the magnetotail.
5
X
Z
Earth’s radiation belt populations are energy dependent.
Van Allen Probes makes possible detailed study of the radiation belts.
& Radiation Belts& Ring Current
5
X
Z
Earth’s ring current is not a ring during storms.
IMAGE HENA made possible detailed study of the ring current.
& Radiation Belts& Ring Current
Courtesy Liemohn, LWS SS
5
X
Z
Earth’s inner magnetosphere makes a lot of waves.
Van Allen Probes makes possible detailed study of the inner magnetosphere.
& Radiation Belts& Ring Current
6
X
Z
Earth’s plasmasphere made visible with EUV
IMAGE spacecraft made observations from outside looking in at the plasmasphere.
Model courtesy of J. Goldstein
& Radiation Belts& Ring Current
Sum up some basic knowledge
1. The bow shock slows, deflects, heat solar wind plasma2. The magnetopause is a barrier between solar magnetic field
and particles and magnetospheric fields and particles. It can be opened during reconnection; stay tuned!
3. The aurora gives us a window (through the filter of MI coupling) into global magnetospheric dynamics and plasma regimes.
4. The magnetotail stores and then explosively releases energy and low energy particles
5. The inner magnetosphere is home to 3 populations of particles that ebb and flow based on sources and losses
6. Outside looking in can reveal large scale structure and dynamics
Magnetospheric variabilityis dependent on Solar (Wind) Variability
1. Interplanetary magnetic field (IMF) direction2. Solar wind dynamic pressure (Pd)
What about variability?
Courtesy Kozyra, LWS Summer School
• Northward IMF: Produces cold dense plasma sheets which can be delivered into the inner magnetosphere if the IMF turns southward
• Southward IMF: Drives strong magnetic activity
Magnetopause – IMF direction - reconnection
Courtesy Dorelli, LWS Summer School
Magnetopause – IMF direction - reconnection
High geomagnetic activity(magnetospheric storms and substorms)
Low geomagnetic activity(fewer storms and substorms)
“Magnetopause phenomena are more complicated as a result of merging. This is why I no longer work on the magnetopause.” --J. W. Dungey
Spacecraft Observations are frequently interpreted in the context of the 2D Dungey cartoon
Measurements of magnetopause reconnection
Measure the “effects” of reconnection, e.g., flow.
Magnetopause – IMF direction - reconnection
Kessel et al., 1996
First observations of Reconnection effects under
northward IMF
Hawkeye spacecraft made possible the study of reconnection with N IMF.
Magnetopause – IMF direction - reconnection
Phan et al., 2003 Cluster and IMAGE spacecraft made possible the study of reconnection.
DeHoffman-Teller
analysis
Wal’en relation
Need evidence that the magnetopause is a rotational discontinuity:• deHoffman-Teller analysis• Wal’en relation
Aurora – window into global magnetospheric dynamics
Courtesy Donovan, LWS Summer School
It often makes sense to use ground-bases auroral (ionospheric) observations to remote sense magnetospheric dynamics
Alaska – Canada – Greenland – Scandanavia - Russia
Courtesy Donovan, LWS Summer School
Aurora – window into global magnetospheric dynamics
Aurora
Courtesy Donovan, LWS Summer School
Aurora – window into global magnetospheric dynamics
Ground-based magnetometer
chains can show global oscillations,
e.g., ULF waves.
4
X
Z
& Radiation Belts& Ring Current
Magnetotail – stores and then explosively releases energy
Nagai et al., 1998a
At 1107 UT on March 30, 1995, Geotail observed fast tailward flows at a speed of >600 km/s in the magnetotail at a radial distance of
15.5 RE. Tailward convection carrying southward magnetic fields was seen
near the neutral sheet.
Geotail spacecraft made possible studies of the magnetotail.
Geotail observations of a fast tailward flow at XGSM = -15 RE
Magnetotail – stores and then explosively releases energy
4
X
Y
Nagai et al., 1998bGeotail spacecraft made possible studies of magnetotail reconnection.
Magnetotail – stores and then explosively releases energy
Geotail made the seminal observations of reconnection in the 23 RE region
Tailward probe ~ 11 RE
Inner probe ~ 9 RE
Dubyagin et al., 2011
Entr
opy
Beginning of B perturbation
Dipolarization front
Flow bursts
Reconnection and inner magnetosphere are linked by short-lived flow bursts
THEMIS spacecraft made possible studies of the magnetotail.
Magnetotail – stores and then explosively releases energy
Flow bursts penetrate into the inner magnetosphere
Kozyra, LWS Summer School 2010
~ Simultaneous double high-latitude reconnection results in large mass transfer from the solar wind into the closed field line region of the magnetosphere.
• Strong long-lived dawn-dusk electric fields associated with the passage of strong southward IMF by the Earth are the primary cause of magnetic storms.
• Energy is transferred to the magnetosphere via magnetic reconnection.• Convects plasma deep into the inner magnetosphere. Along the way it is
adiabatically and non-adiabatically energized to form the stormtime ring current. • Solar wind dynamic pressure enhances the geo-effectiveness.
Overwhelmingly, emphasis so far has been on the IMF direction as a driver of magnetospheric activity. But
solar wind dynamic pressure also has a role.
Recap – Magnetopause – Aurora – Magnetotail
Sudden solar wind pressure increase
causes inward motion of magnetopause
and subsequent loss of high energy electrons.
Turner et al.,2014b
Pdyn
Bz
L*max
rMP
Bz
also
southward
Inner magnetosphere – ebbs and flows based on sources and losses
ULF waves were correlated with the structure of the precipitation.
An azimuthal electric field impulse generated by magnetopause compression caused inward electron transport and minimal loss.
Chorus waves were responsible for most of the precipitation observed outside the plasmapause.
Chorus is excited following injection of 1-30 keV plasma sheet electrons into the inner magnetosphere during geomagnetically disturbed times. [Li et al., 2010]
Could chorus be excited by temperature anisotropy like EMIC?
BARREL
Halford et al., 2015
chorus
Ey
RBSPICE
B - 50 keV
A - 50 keV
GOES
Inner magnetosphere – ebbs and flows based on sources and losses
350 keV 1 MeV 3.5 MeV
Role of seed population and chorus waves Boyd, Spence et al., 2014
350 keV 1 MeV 3.5 MeV
Role of seed population and chorus waves Boyd, Spence et al., 2014
Source > L* 5.5
GOES seessubstorminjection
350 keV 1 MeV 3.5 MeV
Role of seed population and chorus waves Boyd, Spence et al., 2014
radial diffusionenhancement
350 keV 1 MeV 3.5 MeV
Role of seed population and chorus waves Boyd, Spence et al., 2014
Loss process
radial diffusionenhancement
350 keV 1 MeV 3.5 MeV
Role of seed population and chorus waves Boyd, Spence et al., 2014
LocalAcceleration
by chorusGOES seessubstorminjection
350 keV 1 MeV 3.5 MeV
Role of seed population and chorus waves Boyd, Spence et al., 2014
What is next?Instruments improving resolution and each time we learn something new(like better optics on a telescope resolve objects farther away)
Better time resolution, better energy resolution
Miniaturization - the trend to manufacture ever smaller mechanical, optical and electronic products and devices. More use of cubesats and smaller missions.
NASA recently launched the Magnetospheric Multiscale (MMS) Mission 4 spacecraft in close formation flight!