Magnetosphere The and Plasmasphere
CSI 769 3rd section, Oct. Nov. 2005 J. Guillory
Lecture 7 (Oct.18) Bow shock scattering; Magnetosphere structure, charged particle orbits Advance reading: Gombosi Ch.1 & 6 (and/or Parks Ch. 4, 8 &10), Tascione Ch.4, and Sci. Am. Apr. 1991: Collisionless Shock Waves Lecture 8 (Oct. 25) Dawn-dusk electric field; gyrokinetic codes; magnetotail & current sheet Advance reading: Gombosi Ch. 7 & 14, Parks Sec. 7.8 & 11.5), Tasc. Ch 5 Lecture 9 (Nov. 1) MHD codes & boundary conditions; parallel E-fields & precipitation; satellite diagnostics Advance reading: Gombosi Ch. 4 , Parks Sec. 7.7 In conjunction with the last topic: Joel Fedder (NRL) is scheduled for a Space Sciences Seminar on his MHD magnetosphere code, Wed. 10/26, 3:00 p.m., 206 Please attend.
Bow shock
Perpendicular shock
Oblique shock
waves & particles in upstream foreshock
From Sagdeev & Kennel, Sci. Am. Apr. 1991
Foreshock region
Current in shock layer
From G. K. Parks, Physics of Space Plasmas, AW 1991
Components of v along B and the shock surface, for incident & reflected particles
Repeated reflections from solitons near nonsteady shock
From Sagdeev & Kennel, Sci. Am. Apr. 1991
ISEE In-situ B-field measurements across bow shock
Collisionless shock structure
Hybrid code simulation by M. Leroy et al, GRL 8, 1269 (1981)
C. S. Wu, D. Winske et al., Sp.Sci. Revws 37, 63 (1984)
Ion distributions near shock
Phase space in normal direction
Electric potential structure
Incoming particle scattering
Stochastic Injection of Energetic Particles from Bow Shock and from Tailward reconnection region Nonadiabatic because gyroradius ~ B scale-length locally Particle orbit diffusion due to field fluctuations Some particles accelerated near bow shock and magnetic reconnection regions
Magnetic field geometry
Model field topology for northward IMF
IMF + dipole
Model field topology for southward IMF
From G. K. Parks, Physics of Space Plasmas, AW 1991
Field line motion with southward IMF (after J. Dungey, 1961). North is DOWN in this fig.
From G. K. Parks, Physics of Space Plasmas, AW 1991
Detail of day-side reconnection field & flows
Field near reconnection region
(more on reconnection later)
Inner magnetosphere:
Energetic proton density contours, showing South Atlantic anomaly
Mag. dipole offset from rotation axis and tilted
Van Allen Belts
Inner belt energetic protons from cosmic ray albedo neutron decay (CRAND) and from diffusion from elsewhere. Outer belt somewhat energetic ions from solar wind injection and accelerated from ionosphere, and diffusion from elsewhere.
Approx. avg. contours of spatial distribution of trapped energetic protons & electrons
(Van Allen, 1968)
NSSDC quiet-time static empirical model (AP-8) of energetic proton flux density
J. D. Gaffey & D. Belitza, J. Spacecraft & Rockets 31, 172 (1994)
NSSDC quiet-time static empirical model (AE-8) of energetic electron flux density
J. D. Gaffey & D. Belitza, J. Spacecraft & Rockets 31, 172 (1994)
Calculated energetic proton lifetimes (x ne) in inner Van Allen belt under quiescent conditions
R. C. Wentworth, "Pitch Angle Diffusion.. ", Phys. Fluids 6, 431 (1963)
Satellite measurement of proton density vs L, during quiet and CME-arrival conditions
OGO-5 measuremts R. Chappell et al, JGR 75, 50 (1970)
Squeezing the magnetosphere:
quasistatic pressure balance estimate
Ram pressure of CME arrival + IMF v2
vs
interior particle+field pressure Increasing B produces inductive E fields and currents
Energy transfer from CME to magnetosphere: time delay
From Tascione, after Baker et al, JGR 90, 1205 (1985)
Particle currents in the magnetosphere
Ring current reduces B at surface
After CME compression of day-side magnetosphere, Bhoriz at RE decreases ~1 hr after sudden-commencement rise, and stays reduced for 1-3 days, gradually returning to pre-storm values. This is correlated with injection of 10100keV magnetotail particles into ringcurrent region.
Global magnetic change index (Tascione sec 4.7)
K: integer, 0 9 : 3-hr average of B, on quasi-log scale, for each of several ground locations Kp: average of K's from 12 locations between 48 & 63 degrees latitude, averaged with local & seasonal variation filtered out
Dst index (Tascione p.51)
Hourly avg. (from 4 low-latitude ground stations) of changes in horizontal component of B, with seasonal variations subtracted out. A measure of changes in ring-current intensity
AE (Auroral electrojet) index
Spread between max positive & max negative changes in horizontal component of B at several auroral-latitude locations, 62.5 71.6 degree latitudes Global AE = maximum of the positive changes in horizontal component at any such location maximum of the negative changes in horizontal component at any such location
Electric fields and more currents & plasma flows
Plasma corotation-induced E field:
E = - ( x r) x B = BoRE (RE/r)2 (2sin e + cos er) approximately, for dipole B.
Inner part of earth's magnetosphere corotates. Added to dawn-dusk E field due to solar wind
Model E-fields in equatorial plane
Collisionless plasma flow (not currents) in E perpendicular to B
vD/c = E x B /B2
(cgs) , if (as usual) E (cgs) << B (G)
B-Field-aligned currents and fields
High-conductivity acceleration-limited currents along B-lines Downstreaming charges arrive & die at dense ionosphere, producing auroral glow. Upstreaming charges from ionosphere populate plasmasphere and mag'sphere.
From Tascione
Field-aligned ion beam distributions in plasma sheet boundary layer from ISEE-1, 16 Feb 1980. (T.E. Eastman, R.J. DeCoster & L.A. Frank, in Cross-Scale Coupling in Space Plasmas
Velocities for steady-state polar wind with no field-aligned current
S. B. Ganguli, H. B. Mitchell, & P. Palmadesso, NRL Memo Report 5673, 1985
Velocities (magnitude) 70 min after onset of a current of -1 A/m2 at 1500 km
S. B. Ganguli, H. B. Mitchell, & P. Palmadesso, NRL Memo Report 5673, 1985
Heating by these currents
S. B. Ganguli, H. B. Mitchell, & P. Palmadesso, NRL Memo Report 5673, 1985
Particle orbits in inner magnetosphere
Assumptions: B/B is small over a gyroradius & gyroperiod Motion of the particles of interest is collisionless (except if the hit the ionosphere, where they die)
Charged particle orbits, static B:
(for B quasistatic and gradB/ B << rg-1 ) Fast gyration about field line North-south bounce due to "magnetic mirror" force Slow east-west drift due to inhomogeneous magnetic field ExB drifts due to electric fields
Gyration about B-line: rg = mv/qB (MKS units)
c
= qB/ m (MKS units) or qB/mc (cgs)
Sub-kHz to MHz angular frequencies (2f): c ~ 1.76x107 B(G)/ for electrons ~ 104 B(G) for protons
Scale of Proton Gyroradius & Gyrofrequency
0.1 G rg(1 MeV) = 10 km A ( perp/ ) ci = 1000 rad/s; f ci = 160/s .01 G rg(1 MeV) = 100 km A ( perp/ ) ci = 100 rad/s; f ci = 16/s tN-S ~ 1.3 s (L=2) ~50 gyroperiods
Adiabatic invariants
General form hpdq
1. Magnetic moment invariant = pperp2/2mB ( = qrg2/2c) 2. Bounce invariant J = ppards 3. Longitudinal drift invariant (L shell)
North-South bounce motion Determined by pitch-angle of fast velocity vector at magnetic equator, And by energy conservation. If Eparallel =0, each particle's parallel energy is converted to perpendicular energy until it has no more parallel momentum, then it reverses its parallel motion.
Effective magnetic mirror force
When a very-small-size dipole moves along magnetic field lines of an inhomogeneous field, there is an effective "force" parallel to the field line that has magnitude & sign Fparallel = - d B/ds where s measures arclength along the magnetic field. A dipole entering a region of stronger magnetic field thus has a retarding force on it, slowing its parallel motion.
One may ask "How can this be? The magnetic force on a charged particle, qvxB/c, is always perpendicular to v and so can do no work on the particle if B is constant in time." In fact, the particle kinetic energy, m vz 2 + m vy 2 , does not change; only the partition between vz and vy changes. And this change of the direction of v is due to the fact that the particle is not exactly at the position of its guiding center, so the directions of the field lines of B at the particle are not quite the same on opposite sides of the gyro-orbit, leading to a gyro-averaged vxB force that has a parallel component.
The constancy of = ( m vperp 2 ) /B during collisionless nonrelativistic charged particle motion along B, and the constancy of m vpar 2 + m vperp 2 = KE, mean that vpar can be expressed in terms of its value at some reference point so by m vpar 2 = ( m vpar 2)o - (B - Bo), i. e. the parallel motion is derivable from a potential, B. (If there is also a static electric field parallel to the magnetic field, the effective potential for parallel motion of the "dipoles" generalizes nicely to B + q .) When B has a minimum at some reference point so along each magnetic field line encircled (or "enhelixed") by a particle, the collisionless parallel motion will be that of a particle in an effective potential well (remember, though, that the magnetic potential depends on the constant , which is not the same for all particles !).
Half of Loss-cone(s) in magneticequator velocity-space
Shown for no parallel electric field
Particle turns around where ( & if) vpar 2 = 0, where all the energy is converted to perpendicular energy, i. e. at B such that ( m vpar 2)o - (B - Bo) - q( - o) = 0. This turning point equation, with the help of magnetic moment constancy ( m vperp 2 ) /B = ( m vperp 2 ) o /B o , specifies the turning points as where
( m vpar 2)o - ( m vperp 2 ) o (B/Bo - 1) - q( - o) = 0.
When there is negligible parallel electric field this is simply B /Bo = 1 + (vpar2 / vperp 2)o , so each trapped collisionless particle mirrors, i.e. changes its sign of parallel velocity, at a value of B/Bo that depends on its pitch angle at the minimum of the magnetic field. In the reference-plane velocity space {vpar o, vperp o}, one can draw a boundary for any value of B1, such that particles with |v perp o | above the boundary will be trapped in the spatial region where B < B1 , and those with |v perp o | below the boundary can progress to higher values of B than B1 if nothing else stops them first.
Loss regions in midplane velocity space(s) when there is a steady parallel E field toward the ionosphere (positive potential on field line)
trapped
Lost to ionosphere in 1 bounce
Positive potential occurs so as to reduce electron loss rate to the (increased) ion loss rate.
Same thing in midplane energy space
Particle gyration & bounce in inner magnetosphere
From T. Tascione, Intro to the Space Environment
(From G. K. Parks, Physics of Space Plasmas)
Energy conservation (with E=0)
o = pitch angle at mag. Equator ( = 0) Bo = field strength at mag. Equator
Charged particle longitudinal drift due to magnetic field inhomogeneity
Cross-field drift of and + particles under force F
From Parks, Physics of Space Plasmas
Longitude-drift periods (from Parks)
Drift Rate (in terms of energy, mag. Moment, bounce invariant, bounce period, and L)
For static magnetic dipole, with E = 0: <d /dt> = - (2cLRE /e ) (3/2 - J/4 )
with = ds/vy = N-S bounce period, and J = m vy ds = bounce action integral.
T. G. Northrop, in Radiation Trapped in the Earth's Magnetic Field, B. M. McCormac, ed., Reidel 1966
For nonstatic dipole B without shear
(but changes slow enough to preserve J and ):
<d /dt> = - (2c/e )rd (B/B ){(2m(H - B - q)) [(B /B)( /L)(rB/B ) + r B/L ] - (2m(H - B - q))- [2m(H -q)r lnB/L+ rq /L]} with = electric potential and = longitude angle. T. J. Birmingham, "Guiding center drifts in timedependent meridional magnetic fields", Phys. Fluids 11, 2749 (1968)
Ring Current from drifting, gyrating particles
(Parks sec. 7.7.4, with corrections)
(a) From guiding-center drifts Jgc = e (ni vdrift(i) - ne vdrift(e-) ) = n(KE) e [(KE/e) (1 + cos2) bxgradB /B2] bxgradB/ B2 = -3/rB i at = 0
so
Jgc ~ -3n[<KE>i + <KE>e ]/rB
(for equatorial particles)
Igc = JgcdV /2r ~ - 3Etot/(2r2B) (b) From pressure gradient of gyrating particles JgradPperp xB = grad (n[<KE>i + <KE>e ]perp.) IgradPperp ~rdrd grad (n[<KE>i + <KE>e ]perp.)/B ~ + Etot/2r2B
so this (b) current reduces the average net ring current magnetic field by about 1/3. The net ring current then reduces the magnetic field at the magnetic equator at 1 RE by B/B = - (2/3) Etot/Emag , where Emag is the volume-integrated energy in magnetic field.
See more general derivation in R. L. Carovillano & J. J. Maguire, in Physics of the Magnetosphere, (Carovillano et al, ed's), Reidel, 1968. Ring current usually peaks at 4-5 RE (quiet); at 2-4 RE (storm) Mean proton energy: 85keV (90% are in 10 - 250 keV) Quiet-time ring current density ~ 10-8 A/m, increased by factor of several during storms. See Tascione sections 5.4.3, 5.9, 5.10
Typical energy spectrum of energetic protons
Power delivered by solar wind/ CME
Power = Current x (-vxB)dl Current varies as c, i.e. as B
Power varies as B2v sin4(/2) where = angle of IMF from northward sin = 0 for northward IMF sin = 1 for southward IMF J. K. Alexander, L.F. Bargatze, J. L. Burch et al., "Coupling of the solar wind to the magnetosphere" in Solar Terrestrial Physics D.M. Butler & K. Papadopoulos, ed's. NASA, 1984 Tascione, sections 3.7, 5.8, 5.10
Energy injection into ring current
Empirical approximate formula for ring-current addition rate in terms of Dst and ring-currentenhancement lifetime t: UR(J/hr) = 4x1010(dDst/dt + Dst/ t) (Tascione sec.5.10) See Akasofu [Sp. Sci Rev, 28, p160, 1981] for a related formula: |Dst| ~ 60*(log [epsilon] - 18)**2 + 25 where epsilon = B2v sin4(/2)
Nov. 6, 2001 event Southward B component ~80 nT Unusually sharp CME shock with speed >1000km/s Nearly perpendicular shock L=8 SEP's showed sharp rise in # on shock arrival L=3: 14-25 MeV protons arrived minutes before shock and were trapped when shock arrived via front-side & cusp entry stayed trapped til Oct `03 storm detrapped them 3-20 MeV electrons enhanced at first, but deep dropout of total >1MeV electron flux at L=3-8, with few-days recovery time
Mary Hudson's PIC particle follower, riding on Fedder-Lyons-Mobarry MHD code, followed particles from ACE input data
Cluster data (Morikis & Kistler, UNH)
Cluster apogee 20 RE, perigee 4 RE, every ~48 hrs 50 hr orbit, 2hrs in magnetosphere at ~4RE
Sampex data: ~1-3 MeV electrons, 10-20 MeV
electrons
Stochastic Injection of Energetic Particles from Bow Shock and Tailward reconnection region
Nonadiabatic because gyroradius ~ B scale-length locally Timescale varies as 5/4 -1/2 Flux density injected varies as density at low densities M. G. Rusbridge, "Non-adiabatic effects in charged-particle motion near a neutral line", Plasma Physics 19, 1087 (1977) and "Non-adiabatic charged particle motion near a magnetic field zero line", Plasma Physics 13, 977 (1971) W. Peter & N. Rostoker, "Theory of plasma injection into a magnetic field", Phys. Fluids 25, 730 (1982) J. Chen & P. J. Palmadesso, "Chaos and nonlinear dynamics of single-particle orbits in a magnetotail-like magnetic field", JGR 91, 1499 (1986); errata 91, 9025 (1986)
Particle Diffusion
Dominated by field fluctuations in storm conditions.
Lee/Sydora Gyrokinetic Code calculates for Tokamaks. Diffusion model: W. N. Spjeldvik, "Consequences of the duration of solar energetic particle-associated magnetic storms on the intensity of geomagnetically trapped protons", in Modeling Magnetospheric Plasma, T.E. Moore & J.H. Waite, ed's. AGU 1988 J.M. Cornwall, " Radial diffusion of ionized helium and protons: a probe for magnetospheric dynamics" JGR 77, 1756 (1972)
df/dt = L2d/dL (DLLL-2df/dL) - Af + G -1/2df/d A = charge exchange factor, G = Coulomb slowing DLL(L, ) given in Cornwall (1972),
assumes power-law ( -2) spectrum of fluctuations in B and E.
Flow dynamics of charge-neutralized plasma fluid:
[t + Ugrad]U = (1/ o)[(Bgrad)B - grad(B2/2)] - (1/r) divP + g P = pressure tensor = pperp I + (ppar - pperp)bb (div P )perp = gradperp pperp - (ppar - pperp)(bgrad)b (div P )par = (bgrad)ppar + (ppar - pperp)divb div P = gradp for isotropic pressure [t + Ugrad] (pperp/B) = 0 [t + Ugrad]( pparB2/ 3) = 0
G.F. Chew, M.L. Goldberger, & F.E. Low, Proc. Roy. Soc (Lon.) A236, 112 (1956) N.A. Krall & A.W. Trivelpiece, Principles of Plasma Physics, McGraw Hill 1973
Magnetosphere Simulation
Particle codes, incl. gyro-averaged particle followers (e.g. Mary Hudson's at NASA & R. M. Winglee code at UW) Fluid (MHD) codes
Fedder-Lyon-Mobarry code (NRL) BATSRUS (U. Michigan) Spicer code(s): Odin etc. Modified MHD: Winglee
Hybrid (particles and MHD) codes
Rice MSM code Kazeminezhad 2D code
Models are available for community use:
CCMC: http://ccmc.gsfc.nasa.gov/ UCLA: http://www-ggcm2.igpp.ucla.edu/
Source codes in public domain:
GEDAS (Japan, T. Ogino) (Japan, T.) http://gedas22.stelab.nagoya-u.ac.jp/simulation/jst2k/hpf02.htm BATSRUS: http://csem.engin.umich.edu/ NRL: http://www.lcp.nrl.navy.mil/hpcc-ess/software.html
FCTMHD3D (C.R. DeVore) AMRMHD3D (P. MacNeice)
Zeus 3D MHD (Michael Norman): http://zeus.ncsa.uiuc.edu:8080/lca_intro_zeus3d.html Codes: CFD http://icemcfd.com/cfd/CFD_codes.html
Fedder-Lyon-Mobarry (FLM) Code: distorted spherical coord. grid
MHD eqns as solved in FLM code
J. G. Lyon, "Numerical methods used...", Proc. ISSS-7, 26-31 March 2005
FLM Code Does not include particle acceleration (since it's an MHD code) but does show overall energetics of CME coupling for southward IMF, and shows very weak coupling for northward IMF. Coupling is by fast magnetosonic wave propagation from magnetopause. Shows Poynting vector energy flow from these waves.
BATS-R-US Code (U. Mich.)
Block-Adaptive-Tree Solarwind Roe-Upwind Scheme)
Gombosi et al 3D MHD, Eulerian xyz grid (x toward sun) Block-adaptive mesh refinement Cell-centered finite volume method Upwind-differencing Riemann solver (Powell 1994) Efficiently parallelized High computation/communication ratio
Runs on Sun, SGI shared memory, Cray T3D & T3E, and IBM SP2 Simulation box typically 192 RE wide, +192 to -384 RE in x direction Cell size typically .25 RE to 32 RE Inner boundary at 3 RE (no mass flow across it) coupled along assumed dipole B lines to finite tensor conductivity, heightintegrated ionosphere layer at 1 RE [M. L. Goodman, Ann. Geophys. 13, 843 (1995)] Dipole inner field separated off [as in Tanaka, JGR 100, 12057 (1995)]
BATSRUS simulation of outermost closed B lines, for Parker spiral IMF
Winglee modified MHD code
R.M. Winglee, "Regional Particle simulations and Global Two-fluid Modeling of Magnetospheric Current Systems", in J. L. Horowitz et al., Cross Scale Coupling in Space Plasmas, QC 809.P5 C76, 1995 Uses a 2-fluid modified MHD set of equations Gets the injection of currents & plasma across B-field lines
Rice MSM Code
Rice MSM Code
E. C. Roelof, B. H. Mauk, R. R. Meier, K. R. Moore, & R. A. Wolf, "Simulation of EUV and ENA magnetospheric images based on the Rice Convection Model", in Instrumentation for Magnetospheric Imagery II, SPIE 1993. (ENA = energetic neutral atom) Streamlined version of RCM = MSM (magnetic specification model), has non-self-consistent E field from "phenomenological convection patterns".
F. Kazeminezhad new code
2D hybrid Triangular finite-element grid
MagnetoTail
Magnetic Reconnection
Modeling driven reconnection
2-D Compressible Resistive MHD Simulation of Driven Reconnection
S. -P. Jin & W. -H. Ip, Phys. Fluids B3, 1927 (Aug. 1991) Plasma beta at inflow boundary of simulation box: initially 0.1 Alfven Mach # of inflow: MA = 0.15 (for -.5 < z <+.5), tapering to 0 at |z| >1 High Lundquist Number: 400 - 2500 (very low resistivity)
Lundquist Number = ratio of JxB force to resistive mag. diffusion force
Initial Bz(x) profile: half sine wave -w < x < w (w <1), 1 for |x| > w (odd function of x) Initial state in pressure balance Grid resolution in x: x increases 13% every step. Grid concentrated in center near x = 0. Time in units of Alfven-wave x-crossing time. Sim. ~ 40 units. Implicit integration scheme: Y. Q. Hu, J. Comp. Phys 84, 441 (1989)
B lines, v vectors, T(%), (%)
Time
S-P. Jin & W-H. Ip. 2D compressible MHD sim. , PhysFluids B 3, 1927 (1991)
PIC simulation of particle orbits near a magnetic reconnection line
H-J. Deeg, J.E. Borovsky & N. Duric, Phys Fluids B 3, 2660 (1991) Geometry and results shown in following slides
Region where "magnetic insulation" fails, i.e where B is weak
H-J. Deeg, J.E. Borovsky & N. Duric, Phys Fluids B 3, 2660 (1991)
Geometry for PIC simulation of particle acceleration near reconnection region
H-J. Deeg, J.E. Borovsky & N. Duric, Phys Fluids B 3, 2660 (1991)
Proton orbits in views 1 & 2
Proton orbit in views 2 & 3
Energy gain of protons entering near neutral point
H-J. Deeg, J.E. Borovsky & N. Duric, Phys Fluids B 3, 2660 (1991)
Final proton energy vs initial proton energy, for protons initially incoming near neutral point
H-J. Deeg, J.E. Borovsky & N. Duric, Phys Fluids B 3, 2660 (1991)
Turbulence in B-line reconnection
Matthaeus & Lamkin, PhysFluids 29, 2513 (1986)
Contours of constant J Magnetic field
Fluid streamlines
Contours of constant vorticity
Disturbed magnetotail reconnection at current sheet can launch plasmoids & relax (as well as accelerating particles forward & backward)
E. W. Hones, Sci. Am. March 1986
Some references on field-line reconnection
Observations by Cluster satellite: A. Runov et al., Geophys. Res. Lett. 30, 1579 (2003) Observations by WIND satellite: T. D. Phan et al., Nature 404, 848 (2000) ; M. Oieroset, R. P. Lin et al., Nature 412, 414 (2001) 3D PIC simulation: P.L. Pritchett & F. Coroniti, JGR 109, A 01220 (2004) 2D simulation with "guide field" normal to plane: P. L. Pritchett (UCLA): "Onset & Saturation of Guide-field Magnetic Reconnection", Phys. Plasmas 12, 062301 (June 2005)
More references on field-line reconnection
Particle acceleration & orbits: H-J Deeg, J.E. Borovsky & N. Duric (LANL), "Particle acceleration near X-type magnetic neutral lines", Phys. Fluids B 3, 2660 (1991) Electric field enhancements (EFE): J. D. Scudder & F. S. Mozer, "Electron demagnetization and collisionless magnetic reconnection in <<1 plasmas", Phys. Plasmas 12, 092903 ( Sept. 2005) Role of microinstabilities (anomalous resistivity): M. Ugai & L. Zheng, "Conditions for fast reconnection mechanism in 3D" Phys. Plasmas 12, --- ( Sept. 2005)
Satellite sensors
Radiation Belt Mappers GOES (ESA) Cluster, Vortex Doublestar Polar Image Geotail (Japan) ISEE1-3, IMP1-8 & other former sats with elderly data Ionospheric satellites measuring energetic particles: DMSP, SAMPEX etc. Upcoming: NPOESS & NPP
Living With A Star Research Network
Pole Sitter Solar Dynamics Observatory
L1 Solar Sentinel
Ionospheric Mappers L2 Radiation Belt Mappers
Distributed network of spacecraft providing continuous observations Geospace Dynamics Nework with constellations of smallsats in key regions of geospace.
How to find satellite orbit info (& related data) http://pwg.gsfc.nasa.gov/orbits /menu_orbits.html Orbits for Wind, ISTP, Cluster, Image, Polar
Radiation Belt Mappers
Understand origin and dynamics of the radiation belts. Determine time & space-dependent evolution of penetrating radiation during magnetic storms. First Element: multiple spacecraft in 3 petal equatorial orbits; in-situ measurements. Second Element: Add higher latitude coverage.
GOES description
GOES (Geostationary Operational Environmental Satellites, NOAA/ NESDIS) 2 spacecraft at 75deg W and 135deg W, one at 98deg W and/to 108deg W, moved with season. 35,600 km equatorial orbit, spin axis parallel to earth's spin axis. Telemetry to NOAA ERL, Boulder. measuring: solar X-rays, B field at satellite, high energy particles, via SEM (Space Environment Monitor). SEM has (a) Total Energy Detector (TED)- intensity of energetic particles 0.320 keV in 11 bands; (b)Medium-Energy Proton & Electron Detector (MEPED) - 30 keV60MeV; (c) High-Energy Proton & Alpha Detector (HEPAD) - 370 MeV- >850 MeV.
Cluster & Vortex
Cluster & Doublestar (DSP)
Cluster data (Morikis & Kistler, UNH) Cluster: (ESA & NASA, 2000)
Cluster apogee 20 RE, perigee 4 RE, every ~48 hrs 50 hr orbit, 2hrs in magnetosphere at ~4RE
Some Cluster results
Cluster has now proven the existence of The Kelvin-Helmholtz instability as an important solar wind entry process. These large-scale vortices could lead to substantial entry of solar wind to populate the Earth's magnetosphere. (Tai Phan, UCB SpSciLab.)
Polar: orbit
(http://pwg.gsfc.nasa.gov/orbits/aaareadme_polarpar.html
The POLAR orbital parameter plots show the radial distance, eccentric dipole (ED) magnetic local time (MLT), and eccentric dipole L-shell value. The darker segments correspond to times when one of the magnetic footpoints (traced down to 100 km altitude using the T89, Kp=3-,3,3+, model) falls in one of the following regions: cusp, cleft, or auroral oval.
Polar: observation of an event
Images in visible light from the Polar satellite's Visible Imaging System compares the northern auroral regions on May 11, 1999, and a more typical day on November 13, 1999. Credit: University of Iowa/NASA.
Polar, cont'd May 11, 1999 event: solar wind flux dropped a lot produced an intense "polar rain" of electrons over one of the polar caps of Earth. Electrons flow unimpeded along the Sun's magnetic field lines to Earth and precipitate directly into the polar caps, inside the normal auroral oval. Such a polar rain event was observed for the first time in May 1999 when Polar detected a steady glow over the North Pole in X-ray images. Jack Scudder, U. Iowa, PI for the Hot Plasma Analyzer on NASA's Polar spacecraft. Scudder and Don Fairfield of Goddard had predicted the details
In parallel with the polar rain event, Earth's magnetosphere swelled to five to six times its normal size. NASA's Wind, IMP-8, and Lunar Prospector spacecraft, the Russian INTERBALL satellite and the Japanese Geotail satellite observed the most distant bow shock ever recorded by satellites. SAMPEX spacecraft reveal that in the wake of this event, Earth's outer electron radiation belts dissipated and were severely depleted for several months afterward.
Image Satellite ENA sensors
Image website (Southwest Research)
http://pluto.space.swri.edu/IMAGE/
HENA: D. G. Mitchell and HENA team, the Johns Hopkins University Applied Physics Laboratory MENA: C. J. Pollock and J.-M. Jahn, Southwest Research Institute
HENA Images of ENA fluxes during the July 15-16 2000 Geomagnetic Storm
Geotail (Japanese space program)
Instruments: Solar wind, hot plasma, & composition analyzers, directional data on electrons/protons/helium above 20keV, protons above 400keV, electrons above 120kev, B field, etc. http://wwwistp.gsfc.nasa.gov/istp/geotail/geotail_key_para meters.html
DMSP Satellites:
Orbits: circular, sun-synchronous, polar, ~850km alt. 98.7 deg inclination, period 101 min., revisit time 6 hrs. Global coverage @ 12hrs each satellite Communications: S-band, about 3 MBPS in 1995; maybe more capacity now. Design life: 3-5 yrs. Block(group) 5D-2 (5 sats) launched 1991-98, earlier ones presumably now down or inoperative; Block 5D-3 (5 more satellites, S16-20, built by Martin Marietta) launched 1999-06; Block 6 beginning 04.
DMSP, cont'd.
Relevant sensors for space weather: SSI/ES I...