Conference Presentations

Last updated: September 21, 2001

EFI measurements are utilized in work presented at a variety of scientific conferences. This page contains a listing of these presentations organized by meeting. For further information contact AGU.

Presentations specific to the Polar Satellite

AGU Fall 1996 Presentations

AGU Spring 1997 Presentations

AGU Fall 1997 Presentations

AGU Spring 1998 Presentations

AGU Fall 1998 Presentations

AGU Spring 1999 Presentations

AGU Fall 1999 Presentations

AGU Fall 2001 Presentations

AGU January 11-13, 1999 Chapman Conference: Magnetospheric Current Systems

Cluster II Workshop at Imperial College in London, September 22-24, 1999

Non-AGU Presentations

Types of Presentations:

I = Invited      C = Contributed
O = Oral         P = Poster

Paper Number  Type Title and Presenter

    SM21D-04  I/O  Polar Plasma Outflows into the Magnetotail Lobes,
                   Moore et al. P-Polar

    SM21D-09  I/O  Time Domain Structures in the Auroral Acceleration Region,
                   Mozer et al. P-Polar

    SM11D-01  C/O  Polar Observations of ULF Plasma Waves in the Cusp,
	           Pfaff et al. P-Polar

    SM11D-03  C/O  Observations of Electric Fields, Magnetic Fields, 
                   Ion Composition, and Thermal Plasma Variations in the
                   High Altitude Polar Cap and Auroral Zone from the Polar
                   Spacecraft, Wygant et al. P-Polar

    SM11D-04  C/O  Electron Density Measurements by the Polar Electric
                   Field Instrument, Laakso et al. P-Polar

    SM12B-02  C/O  Correlative IMP8-Wind-Geotail-Polar Measurements of
                   Magnetotail Substorms, Angelopoulos et al. P-Polar

    SM31C-02  C/O  The Aurora and the Electron Plasma Sheet,
	           Streed et al. P-Polar

    SM32C-04  C/O  The Plasma Sheet at High Altitude and at the Equator:
                   MPA-Polar conjunctions, Borovsky et. al. P-Polar

    SM42C-11  C/O  Multi-spacecraft Study of Electric Field Penetration
                   into the Earth's Magnetosphere, Turner et al. P-Polar

    SM72A-04  C/P  Polar Electric Field Observations at the Plasma
                   Sheet-Lobe Boundary, Hesse et al. P-Polar

    SM12A-03  C/P  Statistical Maps of Large Scale Convective Flows and
                   Electron Thermal Flux Measurements from the Polar Spacecraft,
                   Johnson et al. P-Polar

    SM22B-02  C/P  Cusp Electrodynamics with Northward IMF Observed by Polar,
                   Maynard et al. P-Polar

    SM22B-04  C/P  Large Amplitude Ion Cyclotron Waves Detected by Polar,
                   Temerin et al. P-Polar

    SM22B-05  C/P  Characteristics of the Quasi-Static Auroral Electric
                   Fields Detected with the Polar Satellite,
	           Weimer et al. P-Polar

    SM22B-09  C/P  Polar Observations of Time Domain Electric Fields at the 
                   Plasma Sheet Boundary, Cattell et al. P-Polar

    SM22B-10  C/P  ULF Electric Fields in the Dayside Magnetosphere:
                   Results from Polar, Clemmons et al. P-Polar

    SM41B-05  C/P  New Observations of Solitary Waves and Weak Double Layers
                   by the Polar Electric Field Instrument,
	           Bounds et al. P-Polar

Types of Presentations:

I = Invited      C = Contributed
O = Oral         P = Poster

Paper Number  Type Title and Presenter

    SM41B-05  C/P  New Observations of Solitary Waves and Weak Double Layers
                   by the Polar Electric Field Instrument,
	           Bounds et al. P-Polar

    SM41E-06       Wave Power Studies of Cusp Crossings With the POLAR
                   Satellite by V. Angelopoulos, F. S. Mozer, M. Temerin,
                   W. K. Peterson, H. L. Collin, and C. A. Kletzing

    SM22B-01  P    Upflowing Ions and Auroral Plasma Density Depletions by
                   H. L. Collin, W. K. Peterson, E. G. Shelley, J. Wygant,
                   J. M. Quinn, F. S. Mozer, and J. D. Scudder 

    SM52C-02       A Search for Plasmaspheric Material in the Lobe Using ISTP
                   by J. E. Borovsky, R. C. Elphic, M. F. Thomsen,
                   D. J. McComas, R. H. Comfort, P. D. Craven, T. E. Moore, and
                   F. S. Mozer

    SM42B-04  P    Thermal Ion Flow Velocities as Measured by Tide and Inferred
                   by EFI and MFE by H. A. Elliott, R. H. Comfort,
                   P. D. Craven, M. O. Chandler, T. E. Moore, F. S. Mozer, and
                   C. T. Russell

    SM41E-07       Observations of Electric Fields and Thermal Plasma Structure
                   in the High and Low Altitude Polar Caps From the POLAR
                   Spacecraft by J. R. Wygant, M. Johnson, J. Scudder,
                   M. Temerin, F. S. Mozer, H. Laakso, H. Collin, W. Peterson,
                   and A. Pedersen 

    SM21B-04       Large Amplitude Ion Cyclotron Waves Observed by FAST and
                   POLAR by M. Temerin, F. S. Mozer, C. W. Carlson,
                   C. C. Chaston, R. E. Ergun, J. P. McFadden, D. Gurnett, and
                   C. Cattell 

    SM41C-09  I/O  Polar Observations of Cusp Electrodynamics: Evolution From
                   2- to 4-Cell Convection Patterns by N. C. Maynard,
                   D. R. Weimer, W. J. Burke, F. S. Mozer, J. D. Scudder,
                   W. K. Peterson, C. T. Russell, and R. P. Lepping 

    SM31A-10  C/P  Multi-Spacecraft Analysis of Electric Field Coupling Between
                   the Solar Wind and the Magnetosphere: ISTP by N. E. Turner,
                   D. N. Baker, T. I. Pulkkinen, H. J. Singer, N. Maynard,
                   F. S. Mozer, R. P. Lepping, K. Ogilvie, T. A. Fritz, and
                   T. Mukai 

    SM54C-01  I    Simultaneous Observations From Solar-Terrestrial Missions:
                   Event Analysis by V. Angelopoulos, T. Phan, D. Larson,
                   F. S. Mozer, R. P. Lin, G. Germany, G. K. Parks,
                   M. Brittnacher, T. Mukai, K. Tsuruda, T. Yamamoto,
                   S. Kokubun, and R. P. Lepping  

    SM32A-01  P    Observations of the Dawn Side Polar Cap at Three Altitudes
                   From Polar and FAST by Y. K. Tung, C. W. Carlson,
                   R. E. Ergun, J. P. McFadden, F. S. Mozer, W. K. Peterson,
                   D. M. Klumpar, E. G. Shelley, L. Tang, E. Moebius,
                   L. M. Kistler, C. A. Kletzing, L. A. Frank, J. B. Sigwarth,
                   C. A. Cattell, J. R. Wygant, J. D. Craven, and R. P. Lepping 

    SM41C-08  I    An Overview of a Separator Region Traversal at the
                   Magnetopause by J.D. Scudder, for the Polar Team  

    SM52C-02       A Search for Plasmaspheric Material in the Lobe Using ISTP
                   by J. E. Borovsky, R. C. Elphic, M. F. Thomsen, 
                   D. J. McComas, R. H. Comfort, P. D. Craven, T. E. Moore, and
                   F. S. Mozer

    SM41E-06       Wave Power Studies of Cusp Crossings with the POLAR
                   Satellite by V. Angelopoulos, F. S. Mozer, M. Temerin,
                   W. K. Peterson, H. L. Collin, and C. A. Kletzing

    SM41E-07       Observations of electric fields and thermal plasma structure
                   in the high and low altitude polar caps from the POLAR
                   spacecraft by J. R. Wygant, M. Johnson, J. Scudder,
                   M. Temerin, F. S. Mozer, H. Laakso, H. Collin, W. Peterson,
                   and A. Pedersen

    SM21B-04  P    Large Amplititude Ion Cyclotron Waves Observed by FAST and
                   POLAR by M. Temerin, F. S. Mozer, C. W. Carlson,
                   C. C. Chaston, R. E. Ergun, J. P. McFadden, D. Burnett,
                   C. Cattell, R. Elphic, and R. Strangeway

Types of Presentations:

I = Invited      C = Contributed
O = Oral         P = Poster

Paper Number  Type Title and Presenter

    SM41A-16  C/P  Characterization of Large Amplitude ULF Waves Observed by
                   the Polar Satellite
                   J. H. Clemmons, H. J. Singer, F. S. Mozer, C. T. Russell,
                   O. W. Lennartsson, W. K. Peterson, J. D. Scudder, and
                   R. F. Pfaff

The Polar satellite accumulated a large number of observations of ULF waves during its first year in orbit. The present work reports on a study of events selected for their large-amplitude excursions in the electric field, as measured by the Electric Field Instrument. In particular, Pc5 waves with amplitudes of 5 mV/m and above are included, with special emphasis on the extremely large (> 10 mV/m) waves observed during the magnetic cloud event of 10-11 January 1997, in which the combination of electric and magnetic measurements allowed characterization as a traveling wave rather than a standing wave. The waves are apparent in particle signatures as well as the fields measurements, so the local plasma environment can be well characterized. The primary focus of the study is the exchange of energy between the fields and particles, with the highlight being the periodic time-energy dispersed ion fluxes.

    SM12D-02  I/O  Campaign 2 on Boundaries in Collisionless Plasmas,
                   Kawano, H., S. P. Savin, N. C. Maynard, and I. Sandahl, IACG

    SM21B-05  ?/?  Simultaneous Observations of Solar Wind Plasma Entry
                   from Fast and Polar
                   Peterson, W. K., H. L. Colin, S. A. Fusilier,
                   D. M. Klumpar, O. W.  Lennartsson, E. G. Shelley,
                   Y.-K. Tung, C. W. Carlson, R. E. Ergun, J. P. McFadden,
                   W. J. Perla, W. J. Burke, J. H. Clemmons, R. P. Lepping,
                   C. A. Kletzing, N. C. Maynard, T. G. Onsager,
                   C. T. Russell, L. Tang, and J. Wygant

    SM22D-06  I/O  Ground-Satellite Correlations of Transient Flows in the
                   Magnetospheric Cusp: Polar and MACCS Observations
                   Hughes, W. J., N. C. Maynard, T. G. Onsager, W. K. Peterson,
                   C. T. Russell, M. J. Engebretson, and T. Moretto

    SM22D-07  I/O  Generation of the Theta Aurora,
                   Chang, S. W., J. D. Scudder, J. B. Sigwarth, L. A. Frank,
                   N. C. Maynard, W. J. Burke, W. K. Peterson, E. G. Shelley,
                   J. B. Blake, C. T. Russell, R. A. Greenwald, R. P. Lepping,
                   G. J. Sofko, J.-P. Villain, and M. Lester

    SM21D-07  ?/?  Electrostatic Shocks: History and Recent Results,
                   F S Mozer

    SM42C-04  ?/?  Correlations Between Wind IMF and Polar EFI Measurements,
                   H Laakso, F Mozer, R Pfaff, J Wygant, and R Lepping

    SM22B-15  ?/?  High-Altitude Auroral Zone Plasma and Electric Fields,
                   C A Kletzing, J D Scudder, J Wygant, and F S Mozer

    SM52A-07  ?/?  POLAR Electric Field Instrument Observations of Reverse
                   Polarity Solitary Waves
                   *S Bounds, R Pfaff, S Knowlton, F Mozer, M Temerin,
                   C Kletzing, and C Russell

    SM32C-06  ?/?  Review of the Evidence for In Situ Penetration of the
                   Diffusion Region for BZ > 0 at High Latitude Magnetopause
                   Approaches
                   J D Scudder, F S Mozer, J S Pickett, C T Russell,
                   T E Moore, and W K Peterson

    SM32A-06  ?/?  Low Frequency Wave Characteristics of Low Altitude Cusp
                   Crossings With the POLAR Satellite,
                   V Angelopoulos, F S Mozer, M Temerin, M Somoza,
                   W K Peterson, H L Collin, E G Shelley, C A Kletzing, and
                   B Giles

    SM41A-16  ?/?  Characterization of Large Amplitude ULF Waves Observed by
                   the Polar Satellite,
                   J H Clemmons, H J Singer, F S Mozer, C T Russell,
                   O W Lennartsson, W K Peterson, J D Scudder, and R F Pfaff

    SM42C-06  ?/?  Multi-point Observations of Bursty Bulk Flows From Variable
                   Altitudes,
                   V Angelopoulos, W Peria, T Phan, F S Mozer, C W Carlson,
                   R P Lin, M Somoza, J Chapman, M Fujimoto, T Mukai,
                   T Yamamoto, K Tsuruda, and S Kokubun

    SM12C-04  ?/?  Stepwise Approach Towards a Magnetospheric Laboratory,
                   P Harvey, V Angelopoulos, *G T Delory, C W Carlson,
                   F S Mozer, R P Lin, D H Pankow, and J H Primbsch

    SM22B-16  ?/?  Association of Intense Electric Fields Near the Plasma Sheet
                   Boundary With Auroral Phenomena,
                   A Keiling, M J Johnson, C R Cattell, J R Wygant,
                   M B Temerin, F S Mozer, M Brittnacher, G Parks, C Kletzing,
                   J D Scudder, H Collin, W Peterson, and C T Russell

    SM52B-07  ?/?  Ion Outflow and Convection in the Polar Cap and Cleft as
                   Measured by TIDE, EFI, MFE, and TIMAS on Polar
                   H A Elliott, R H Comfort, P D Craven, M O Chandler,
                   T E Moore, N C Maynard, W K Peterson, O W Lennartsson,
                   E G Shelley, F S Mozer, and C T Russell

    SM51B-03  ?/?  Tailward Energetic Ion Streams Observed in the Deep Tail
                   Associated With Substorms: A Detailed Case Study
                   S Rouquette, C Jacquey, D G Williams, R W McEntire,
                   A T Y Lui, S P Christon, T Nagai, T Mukai, T Yamamoto,
                   V Angelopoulos, F S Mozer, S Kokubun, K Tsuruda, G D Reeves,
                   R D Belian, and T J Hughes

    SM51B-04  ?/?  Tailward Energetic Ion Streams in the Deep Tail Associated
                   with Substorms: Electromagnetic Signatures,
                   C Jacquey, S Rouquette, P Louarn, V Angelopoulos, F S Mozer,
                   S Kokubun, K Tsuruda, T Yamamoto, T Mukai, D G Williams,
                   R W McEntire, A T Y Lui, S P Christon, W R Paterson,
                   L A Frank, G D Reeves, and T J Hughes

AN: SA22B-02
TI: On The Internal Inconsistency Of The Interpretation Of Dark Pixel
    Clustering Data As Small Comets
AU: F. S. Mozer
AU: J. P. McFadden
AU: J. Vernetti
AU: I. Sircar
AB: Approximately 700,000 dark pixel clustering events observed by the
    VIS Earth Camera on the Polar satellite during a 120-day interval in
    1997 are described in a catalog produced by Frank and Sigwarth. The
    internal consistency of these events is examined under the two
    hypotheses, that they were produced by small comets and that they are
    the tail of the instrument generated clustering distribution. The
    cluster occurrence rate, its variation with altitude, and the altitude
    dependence of clustering sizes are inconsistent with the small comet
    hypothesis and are fully explained as instrument noise. A portion of
    the dark pixel clustering in this data set is due to underestimating
    the standard deviation of the counts in a pixel. This underestimate is
    largest in the outer radiation belt where most of the apparent dark
    clustering events were found. 

AN: SA22B-03
TI: An Instrumental Source for the Dark Pixel Clusters Observed by the
    Polar VIS and UVI Imagers
AU: J. P. McFadden
AU: F. S. Mozer
AU: J. Vernetti
AU: I. Sircar
AB: The VIS and UVI imagers on Polar both produce non-Poisson
    distributions of dark pixel clusters. The non-Poisson distribution for
    the VIS instrument has been interpreted as evidence for small comet
    bombardment of the upper atmosphere. An alternative hypothesis, that
    this distribution arises from instrumental effects, has been tested by
    a computer simulation that included the imager's pixel point spread
    function (the spatial extent of the light pulses incident on the
    imager's CCD pixel plane) and the exponential distribution of light
    pulses from the image intensifier. These effects fully explain the
    non-Poisson distributions in both instruments without the need for
    invoking external phenomena. 

AN: SM22A-10
TI: More results from IACG Campaign 2
AU: H. Kawano
AU: S. P. Savin
AU: N. C. Maynard
AU: I. Sandahl
AB: The IACG campaign 2 is meant for boundaries and boundary layers
    observed by IACG/ISTP missions (e.g., Geotail, Wind, Interball, Polar,
    Cluster, SOHO, and ground observations). The campaign started in mid
    1997 with four coordinators who are also the authors of this paper. At
    the last AGU meeting we introduced the organization of the campaign,
    drew audience's attention to candidate campaign events in the future,
    and presented a few candidate campaign events in the past. Now we have
    an official web page for the campaign at http://www-ssc.igpp.ucla.edu/IACG/.
    The web page includes lists of candidate campaign events in the past
    and in the future, and describes the background, organization, and
    rules of the road of the campaign. As stated there, the campaign is
    meant to be as open as possible. In this paper we report the progress
    of the campaign since the time of the last AGU meeting. We introduce a
    few events which are newly selected as candidates of campaign events.
    Topics of the events include, e.g., substorm effects near the
    magnetopause, and multipoint observations of the magnetopause.

AN: SM22B-02
TI: Magnetosphere-Ionosphere Coupling and Convection in the Polar Cap
AU: *N. C. Maynard
AB: A large portion of our knowledge of convection at high latitudes is
    derived from empirical studies of electric fields and ion drift in the
    ionosphere. Critical to understanding the source regions for these
    patterns is the mapping of the patterns out into the magnetosphere.
    For instance, dayside convection patterns in the vicinity of the cusp
    map to the whole dayside magnetopause, while the potential maximum and
    minimum in the convection patterns map well down the flanks indicating
    significant flux tube opening on the flanks. The nightside open-closed
    boundary maps to the x-line that is controlling lobe flux merging. Its
    position and dynamics are indicative of tail configuration and the
    rate of energy release in the tail. The evolution of two-cell
    convection patterns to distorted two cell patterns and eventually to
    four-cell patterns as the clock angle decreases toward zero, as well
    as where they map, will be discussed in light of recent Polar
    results.

AN: SM32A-13
TI: Further Analysis of Solitary Waves Observed in the Auroral
    Acceleration Region by the POLAR Electric Field Instrument
AU: *Scott R. Bounds
AU: Robert Pfaff
AU: Craig Kletzing
AU: Forrest Mozer
AU: Mike Temerin
AB: Results of a continuing analysis of solitary waves observed by the
    POLAR Electric Field Instrument are presented. POLAR EFI has observed
    two distinctively different types of solitary waves. The first type is
    identical to those seen by previous auroral zone satellites such as
    S3-3 and Viking. These solitary waves are seen in regions of
    up-flowing ion beams. The second and new type has a faster propagation
    velocity than the first and is seen in regions of upward accelerated
    electrons. This second type of solitary wave is characterized by a
    reversed polarity of the structure in the spacecraft frame, consistent
    with a reversal in the current direction. Such waves have also been
    observed by FAST [Ergun et al., 1998] and are referred to as fast
    solitary waves. Analysis of both types of solitary waves and their
    differences is presented. Ergun, R., C. Carlson, J. P. McFadden, F. S.
    Mozer, G. T. Delory, W. Peria, C. Chaston, M. Temerin, R. Elphic, R.
    Strangeway, R. Pfaff, C. A. Catell, D. Klumpar, E. Shelley, W.
    Peterson, E. Mobius, L. Kister, "Fast satellite observations of
    large-amplitude solitary structures", GRL, Manuscript in
    publication

AN: SM32D-13
TI: ULF/ELF Electric Field Signatures in the High Altitude Cusp
AU: *R Pfaff
AU: S-Y Hsieh
AU: J Clemmons
AU: J Scudder
AU: C Kletzing
AU: J Pickett
AU: C Russell
AU: F Mozer
AF: 5
AB: Instruments on the Polar spacecraft have gathered comprehensive
    plasma measurements in the earth's cusps under a variety of solar wind
    conditions. Consistent features of these cusp encounters are intense
    (5-10 mV/m rms), localized ULF/ELF electric field structures as well
    as distinct keV dispersed ion injections and magnetic field ULF
    perturbations. The DC electric field instrument (EFI) provides a
    detailed picture of the relationship of the broader band (0.05-20 Hz)
    turbulent-like wave features with the lower frequency (DC-0.05)
    electric fields which frequently include "spikey" waveforms. In some
    cases, the EFI burst memory extends the electric field frequency
    response to 800 Hz and also includes AC magnetic field (search coil)
    waveforms. By combining the low frequency electric and magnetic field
    data, we address the energy flow associated with the wave fields which
    also provides important information concerning their source region.
    Although the data suggest that the higher frequency waves are
    controlled by the lower frequency structures, the appearance of ULF
    waves without higher frequency spectral extensions implies that two
    generation mechanisms are present, or that wave damping is
    considerable for the higher frequencies under certain plasma
    conditions. The combined wave and particle observations address
    several aspects of high altitude wave instabilities in the cusp as
    well as other, larger-scale processes.

AN: SM41C-09
TI: Polar Observations of Solitary Waves in the Auroral Zone, the Plasma
    Sheet Boundary, and the Cusp
AU: J Dombeck
AU: *C A Cattell
AU: J Crumley
AU: F S Mozer
AU: M Temerin
AU: M K Hudson
AU: V Marchenko
AU: C T Russell
AU: R Pfaff
AB: Solitary waves and double layers have been observed at altitudes
    ranging from ~1000 km to 10,000 km in the auroral zone. In addition,
    Geotail observed small amplitude (<~0.1 mV/m) in the distant plasma
    sheet. We will describe observations of solitary waves by the Polar
    satellite, both at low altitudes in the auroral zone, and at high
    altitudes (radial distances of ~5-8 Re) at the plasma sheet boundary
    and at cusp particle injections. The waves are usually observed in
    regions of field-aligned current. The high altitude solitary waves are
    much larger amplitude than those in the distant tail and sometimes
    larger than those in the auroral zone. By examining the time delay
    between opposing sensors, the propagation velocity can be determined.
    Preliminary results show that the high altitude solitary waves
    propagate much faster (~1000 k/s) than the low altitude solitary waves
    (100 s of k/s). These results will be compared to simulations and
    theories of solitary waves. We will also discuss the significance for
    particle acceleration in these regions.

AN: SM41C-07
TI: Polar Observations of Intense Electric Fields at the Outer Boundary of
    the Plasma Sheet in Association with Aurora
AU: *J R Wygant
AU: A Keiling
AU: M Temerin 
AU: F S Mozer
AU: C Kletzing
AU: J D Scudder
AU: M Brittnacher
AU: G Parks
AU: W Peterson
AB: In this paper we present observations of large amplitude electric
    fields near the boundary of the plasma sheet at altitudes of 4-6 Re
    near local midnight obtained from the U.C. Berkeley Electric Field
    Instrument on the POLAR spacecraft. The plasmasheet is identified
    using measurements of ion and electron fluxes from the University of
    Iowa Hydra instrument. The electric fields have amplitudes up to 100
    mV/m roughly normal to the plasmasheet boundary. They are associated
    with magnetic field fluctuations with amplitudes of 40 nT directed
    transverse to the local magnetic field lying nearly in the plane of
    the plasmasheet.The period of these fluctuations is of about 60
    seconds and they last about 3 minutes (3 cycles). During some
    encounters with the boundary of the plasmasheet, these acomponents of
    the electric and magnetic field fluctuations are in phase with each
    other-consistent with earthward propagation of Alfvenwaves with phase
    velocities of 2000-3000 km.The interpretation of these electric fields
    in terms of steady state electrostatic shocks and field aligned
    currents will also be discussed. During other passes,the fluctuations
    are dephased suggesting formation of structures which are partly
    standing and partly propagating. We also present evidence on faster
    time scales of high amplitude electric(~200 mV/m) and magnetic field
    (~3 nT) fluctuations. These waves typically have durations of about 1
    second (fcH~6 Hz) and are also polarized perpendicular to the magnetic
    field. Hydra measurements provide evidence for strong fluxes of
    outflowing ions coincident with the appearance of the strong electric
    fields 60 second duration electric fields. Some of the passes we have
    investigated with Hydra data show velocity dispersed ions alternately
    bouncing between the northern and southern hemisphere within 1-3
    minutes of the appearance of the plasmasheet at the spacecraft.
    Simultaneous images from the University of Washington/MSFC UVI imager
    are presented. The intense electric fields generally coincide with
    bright aurora and map to within about 1 degree accuracy to the
    poleward boundary of a bright auroral emission region.

AN: SM52C-03
TI: Reconnection Layer Geometry, Topology, Flow Characteristics and
    Penetration of the Diffusion Region for Northward IMF Poleward of the
    Cusp
AU: *J.D. Scudder
AU: P. Puhl-Quinn
AU: J.c. Dorelli
AU: H.J. Cai
AU: S.-W. Chang
AU: N. Maynard
AU: F.S. Mozer
AU: T. Onsager
AU: C.J. Farrugia
AU: K.W. Ogilvie
AU: C.T. Russell
AU: T.E. Moore
AU: J.S. Pickett
AU: S. Fuselier
AU: W.K. Peterson
AU: R.B. Torbert
AU: R.W. Fillius
AB: An ensemble of 18 Walen tests for anisotropic plasmas have been
    successfully performed during the six hour interval of May 29, 1996
    when the Polar spacecraft skimmed the current carrying layer of the
    magnetopause during northward IMF conditions. These tests were
    performed while the spacecraft traversed the current carrying layer
    and makes use of the fact that the magnetic field is more nearly
    "frozen" into the electron's frame of reference than the ions. With
    this technique the Walen test, which is a restatement of conservation
    of E_T, can be pursued in thinner regions than ever before. These are
    the first tests of the Walen condition near the cusp for northward IMF
    and imply multiple traversals of locally planar rotational
    "discontinuities", a necessary feature of all MHD pictures of
    reconnection. The Walen fits are also accompanied by slope
    determinations that agree within 30\% of the value suggested by the
    Walen relation (cf. Puhl-Quinn et al at this meeting). This paper
    demonstrates the overall spatial organization of the local normals to
    the current layers, the normal component of B, the inflow and exhaust
    Mach numbers, and the organization of the sign of the mass flux across
    this layer as a function of magnetic latitude. We also illustrate the
    topology of the magnetic separatrix using the heat flux of electrons
    as tracers. We demonstrate that the data are consistent with a
    persistant mass flux across this current layer into the magnetosphere;
    and, that the spatial organization of the normal component of B at
    these layer crossings is consistent with the idea that there was a
    traversal, or very near traversal of the "diffusion" region. This
    traversal is delineated by a normal mass flux signal that does not
    reverse when the normal component of B is inferred to change, a
    necessary condition from the Walen condition if the mass flux is to be
    always from the magnetosheath into the magnetosphere on {\it both}
    sides of the diffusion region. The time series of these crossings are
    consistent with multiple crossings of the diffusion region proper,
    with the normal component of B being constant for 10-30sec with
    opposite polaritites, while the field magnitude is severely depressed.
    There is also evidence of strong, low and high frequency electric
    field variations in the weak magnetic field regions of these current
    sheets. Variations of the electron pressure {\it anisotropy} and {\it
    gyrotropy} are now clearly in evidence within these current carrying
    layers. This is made most clear by using the highest possible time
    resolution magnetic field data. These test have been made at the 13.8
    sec resolution of the three dimensional moments of the distribution
    function and the departures from gyrotropy are also seen in the
    distribution functions themselves with a time aliasing interval of
    23msec. These signatures together with theory are strongly suggestive
    of the importance of the {\it full} electron pressure tensor in an
    adequate theory of reconnection relevant for the magnetopause (cf.
    also Cai and Scudder this meeting).

AN: SM42A-06
TI: Cavity Modes in the Plasmasphere: Numerical Simulation and Observation
AU: *J Goldstein
AU: M K Hudson
AU: W Lotko
AB: Although it has been demonstrated theoretically that the
    magnetosphere can act as a resonant cavity for Ultra-low frequency
    (ULF) magnetosonic waves, conclusive evidence for cavity modes is
    relatively rare. In an attempt to close the gap between the cavity
    mode theory and the scarcity of evidence to support it, a data-based
    numerical model has been developed that is directly and quantitatively
    comparable with satellite and ground magnetometer data. The model is a
    linearized ideal MHD dynamic simulation of the plasmasphere,
    implemented on a dipole grid. Model results are compared with
    measurements from the POLAR EFI [courtesy F.Mozer] and MFE [courtesy
    C.Russell].

Electric ULF Waves Measured by the Polar Spacecraft

J. H. Clemmons, The Aerospace Corporation, El Segundo, CA
F. S. Mozer, University of California, Berkeley, CA
H. Laakso, Finnish Meteorological Institute, Helsinki, Finland
R. F. Pfaff, NASA/Goddard Space Flight Center, Greenbelt, MD
P. J. Chi, C. T. Russell, University of California, Los Angeles, CA

                            SM22C-09

Electric and magnetic measurements from the Polar spacecraft are 
used to characterize magnetospheric ultra-low frequency (ULF) waves
in the Pc3-5 frequency range.  Polar's high-altitude, high-inclination 
orbit gives a unique perspective on the waves, and the combination of 
electric and magnetic measurements provides a powerful analysis tool 
for the determination of wave nodal structure, standing wave character, 
polarization, and energy flow.  Results from a survey of more than two 
years of Polar data are presented.  Preliminary analyses indicate that
power in the electric component is peaked near noon, with lower 
frequencies having narrower peaks.  In keeping with previous results
from geosynchronous orbit, the electric component generally has more
power in the azimuthal direction than in the radial direction, indicating
the prevalence of poloidal modes.  Further analyses and comparison to
the magnetic perturbations are discussed.

Polar comparisons of solitary wave characteristics in the auroral zone, the
plasma sheet boundary and the high altitude cusp and their relationship to
particle distributions

C. A. Cattell, J. Dombeck, F. Mozer,M. Temerin,C. Kletzing, R. Pfaff and
W. Peterson

Solitary waves have been observed by the Polar electric field instrument in
many regions of the magnetosphere, including the low altitude auroral zone and
cusp, the high altitude  cusp and polar cap, and the plasma sheet boundary.
Preliminary  studies show that the propagation speeds of the waves are, on
average, systematically different in each of these regions. In the auroral
zone, solitary waves in upflowing ion beam regions propagate upward at
~100-200 k/s; in the plasma sheet boundary, the velocities are usually
~1000 k/s; and, in the high altitude cusp at the edges of energetic particle
injections, they are ~1000 k/s downward. The waves at low altitudes have the
largest amplitudes (on average), while those in the high altitude cusp have
the smallest amplitudes (on average). The scale sizes of the solitary waves in
all regions are the order of 10Õs of Debeye lengths. An explanation based
on observed particle distributions and previous analytic studies and
simulations of i! ! on acoustic solitary waves is proposed. For the high
altitude events, an alternative explanation based on electron acoustic waves
is also discussed. The association of solitary waves with other wave modes,
including whistlers, lower hybrid waves, and ion cyclotron waves are also
described.

O-shaped potential: a new way to look at auroral acceleration.

Janhunen, P., Olsson, A., Laakso, H., Peterson, W.K., Scudder, J.D., Carlson,
C.W., Russell, C.T.,

We have found evidence that an O-shaped potential can describe the
electric field structure above auroral arcs and inverted-V regions
better than the traditional U-shaped model can do. We have come into
this conclusion by using many different techniques and datasets. All
methods rely partly on POLAR northern hemisphere auroral passes,
during which the spacecraft is at about 4 $R_E$ altitude. Some of the
observations that speak in favour of the O-shaped potential model are:

(1) POLAR electric field data shows the absence of the upward continuation
of the lower altitude U-shaped potential in a great majority of cases.

(2) Conjugate studies between FAST and POLAR above auroral arcs show that
outflowing ionospheric ions are cold when detected by POLAR/TIMAS ion
detector, implying that there is no net potential difference between FAST
and POLAR, even though FAST sees typical inverted-V electrons. 

(3) The electron thermal energy from POLAR/HYDRA (roughly 5 keV) is
similar to the electron energy seen by FAST. If there was a net potential
drop, FAST should see a higher energy. 

It is important to note that an O-shaped potential filters out the
low-energy part of the magnetospheric electron population and can
produce the usual inverted-V low-altitude electron spectra. Thus, an
O-shaped potential can explain these observations equally well as the
traditional U-shaped one.

We expect an O-shaped potential to form whenever the thermal current of
hot magnetospheric electrons exceeds the amount of field-aligned
current that the magnetosphere is willing to give, or the ionosphere is
willing to take. The study shows that such a situation might be quite
common, more common than a U-shaped potential.

Recent results from space-based electric field measurements in and around the
cusp

Maynard, N C, Mission Research Corporation
              One Tara Blvd., Suite 302 Nashua, NH 03062  United States

                                    SM31B-08

The combination of the electrodynamics and particle signatures provides
important clues relative to the structure and temporal behavior of the cusp
region.  For instance, the cusp may cover over 3 hours of local time and map to
regions of the magneto-pause behind the terminator as well as to the dayside.
Significant flux tube opening must occur on the flanks of the magnetopause.
Merging is both temporally and spatially variable.  The effects of
time-varying, repetitive local enhancements of merging are seen in the particle
and electric-field signatures at all cusp altitudes and in the ground based
observations of dayside break-up.  Recent Polar measurements with northward IMF
have shown that merging on the poleward edge of the cusp is both temporally and
spatially variable, analogous to the flux transfer events observed on the
equatorward edge for IMF southward.  Recent results from Polar, DMSP and
sounding rockets will be combined to infer magnetopause source region mapping
for different IMF configurations.

Multi-point Satellite and Ground Station Correlations of Transient Flows in the
Polar Cusp Ionosphere

Walker, K A, Department of Astronomy and Center for Space Physics,
        Boston University
Hughes, W J, Department of Astronomy and Center for Space Physics,
        Boston University
Maynard, N, Mission Research Corporation Nashua, NH
Onsager, T, NOAA Space Environment Center Boulder, CO
Peterson, W K, Lockheed Martin Space Physics Laboratory
Scudder, J D, Department of Physics, University of Iowa Iowa City, IA
Trattner, K J, Lockheed Martin Space Physics Laboratory

                                      SM31B-09

We correlate the IMF and solar wind, POLAR observations in the cusp, and plasma
flows in the dayside ionosphere as seen by ground-based magnetometers, to
investigate how the cusp and high-latitude ionosphere respond to solar wind
changes.  POLAR plasma and field data from the HYDRA, TIMAS, MFE, and EFI
instruments are used to identify POLAR cusp-crossings.  We select crossings of
the northern polar cusp for which the POLAR magnetic footprint is near the
magnetometer chains of Greenland and the Hudson Bay region of Canada.  Solar
wind satellites are used to look for correlations between the IMF and
transients observed by POLAR and in the ionosphere.  The solar wind satellites
most useful in this study are near the earth-sun line, upstream in the solar
wind since these spacecraft are most likely to observe the structures that
impact the magnetosphere.  The plasma flows in the dayside polar ionosphere
are determined from the time series data from the magnetometer ground stations
under the assumption that the magnetic perturbations are primarily due to
ionospheric Hall currents.  A linear interpolation between the ground stations
aids the analysis of the two-dimensional images of the plasma flows.  Delays
consistent with Alfven travel times are observed between changes seen at POLAR
and the corresponding changes in the plasma flows seen by the magnetometer
ground stations.  Once a change begins in the plasma flow, it quickly spreads
over the dayside polar cap.  We find that changes in dayside polar cap plasma
flows are driven by changes in the IMF and that there is a rapid globalization
of changes in the flow pattern.

Mapping of Ionospheric Auroral Features Associated With the Prenoon Boundary
Layer to the Magnetosphere

Ober, D M, Mission Research Corp.
Maynard, N C, Mission Research Corp.
Weber, E J, Air Force Research Laboratory
Farrugia, C J, Space Science Center, University of New Hampshire
Sandholt, P E, Department of Physics, University of Oslo
Moen, J, University Cources on Svalbard Longyearbyen
Scudder, J D, Department of Physics and Astronomy, University of Iowa
Russell, C T, Institute of Geophysics and Planetary Physics,
              University of California

                                      SM41A-03

Allsky images at 557.7 nm (green) and 630.0 nm (red) from Ny Alesund are used
in conjunction with POLAR over-flight observations made by the HYDRA, EFI, and
MFE instruments on Nov. 27, 30, and Dec. 3, 1997 to determine the mapping of
dawn side auroral features to the outer magnetosphere.  Using the Tsyganenko 96
magnetic field model, an appropriate mapping is found by adjusting measured
solar wind parameters from the WIND spacecraft to match model and measured
magnetic fields and to match HYDRA precipitation features with the observed
aurora.  Having established the best fit to the data along the POLAR footprint,
the whole allsky image was mapped to the magnetosphere.  Multiple discrete red
aurora bands, identified in these cases as boundary layer precipitation
[Farrugia et al., This Meeting], are found to map to the dawn side low latitude
boundary layer.  The exact mapping location on the dawn flank of the low
latitude boundary layer of the auroral features is dependent on details of the
magnetic field model chosen; however some of the observed arcs map well behind
the dawn terminator.  Equatorward diffuse green aurora, whose source is
identified as from higher energy electron precipitation, is found to map into
the pre-noon dayside magnetosphere in the dayside extension of the plasma sheet
next to the boundary layer.  Differences between results from driving the
Tsyganenko 96 model with best fit versus actual solar wind conditions will be
discussed, along with implications of convective motions and source regions of
the aurora.

A Correspondence Between a Mixing Region in the Boundary Layer and
Morningside Multiple Auroral Forms: Coordinated Wind, Polar, and
Ground-based Observations

Farrugia, C J, Space Science Center, University of New Hampshire
Sandholt, P, Physics Department, University of Oslo
Moen, J, University Courses on Svalbard
Maynard, N C, Mission Corporation
Scudder, J D, Department of Physics and Astronomy, University of Iowa Iowa City

                                      SM41A-06

We describe observations made by the Hydra instrument on Polar on November 30
and December 3, 1997 in the ~0900-1000 magnetic local time (MLT) sector,
coordinating these with ground optical observations of the corresponding
auroras.  The ground instrumentation consists of a photometer scanning along
the magnetic meridian, monitoring auroral precipitation within the latitude
range from 70 deg to 80 deg magnetic latitude (MLAT), and an all-sky camera
covering an area of ~700 km radius.  Polar's ionospheric footprint crossed the
field-of-view of the optical auroral instruments at Ny Alesund, Svalbard,
located at 75 deg MLAT, moving south.  Polar traversed a filamentary
precipitation at a radial distance of ~6 Re, which we attribute to a
structured boundary layer composed of a mixture of magnetosheath and
magnetospheric populations (mixing layer).  Thereafter it crossed into
precipitation from the boundary plasma sheet, and, later still, the central
plasma sheet.  The relevant IMF and solar wind parameters during the
observation of the mixing layer were different: On November 30, the IMF clock
angle was smaller <45 deg versus generally >90 deg) and the dynamic pressure
was higher (average of 5.5 nPa versus 1.2 nPa) than on December 3, and the
Bx and By polarities were reversed.  The Polar-ground conjunction enables us to
show that the multiple arcs typical of the mid-morning MLT sector at
~75-78 deg MLAT are due to precipitation from a boundary layer consisting of a
mixture of magnetosheath and magnetospheric particles.  The boundary layer
source identification is also consistent with the mapping work given in a
companion paper by Ober et al. The stability of the aurora allows us to
identify this as a spatial rather than a temporal feature.  Here, the
persistence for tens of minutes of the corresponding auroral forms suggests
that this mixing layer is a quasi-steady feature on these two passes.  From the
ground observations we infer that the Polar observations were made dawnward of
the westward edge of the cusp, an inference which might not have been drawn
from Polar data alone.  The identification of a mixing region in the boundary
layer is supportive of recent work on the structure of the flank low latitude
boundary layer with in-situ measurements, though our two case studies encompass
a variety of IMF orientations.

Observations of fluxes of magnetosheath origin by Polar and Interball at high
latitudes behind the terminator - relationships to the magnetospheric "sash"

Maynard, N C, Mission Research Corporation
Savin, S, Space Research Institute, Russian Academy of Sciences
Wilson, G R, Mission Research Corporation
White, W W, Mission Research Corporation
Yermolaev, Y, Space Research Institute, Russian Academy of Sciences
Nemecek, Z, Charles University Prague
Safrankowa, J, Charles University Prague
Sandahl, I, Swedish Institute of Space Physics
Kawano, H, Dept. of Earth and Planetary Sciences, Kyushu University 33
Peterson, W K, Lockheed Palo Alto Research Laboratories
Scudder, J D, Dept. of Physics and Astronomy, University of Iowa

                                   SM42A-05

Polar and Interball were both located behind the terminator in the dusk-sector,
high-latitude magnetosphere during the afternoon of January 12, 1997, when the
IMF was dominated by a By component near 5 nT.  In this IACG campaign 2 study,
Polar observed He++ fluxes on the poleward side of the dusk convection
reversal, indicating solar wind origin.  Interball-Tail crossed the high
latitude magnetopause into the magnetosheath at GSM coordinates of
(-10, 13, 13).  Recent magnetospheric modeling results for a pure IMF By of
5 nT [White et al., GRL, 1998] indicate a "sash" structure of low magnetic
field strength, extending from near the cusp, back along the dusk high latitude
flank, to the equatorial flank near 30 Re.  This is a locus of antiparallel
merging sites.  The position of the Interball-Tail, Magion-4, and Polar
satellites compared with the model show the satellite results to be associated
with the sash.  These data and Geotail data in the center of the tail will be
discussed in the context of the model.

Signatures of Collisionless Reconnection within the ``Diffusion'' Region at the
Magnetopause

Scudder, J D, University of Iowa, Department of Physics and Astronomy
Puhl-Quinn, P A, University of Iowa, Department of Physics and Astronomy
Mozer, F S, University of California-Berkeley, Space Sciences Lab
Maynard, N C, Mission Research Corporation
Russell, C T, University of California-Los Angeles, IGPP

                                      SM71B-07

The electrodynamic signatures of reconnection in the form of measured current
and electric fields parallel to the magnetic field have been observed within a
distended interval on the May 29, 1996 northern polar cusp magnetopause
encounter.  The algebraic signs of these independent measurements consistently
indicate the temporal decay of the electric and magnetic field energy density.
The parallel electric components are almost entirely determined by the long
spin plane wire antennas and can be as large as 10mV/m in this interval.  The
parallel current densities are also well above the error for their direct
determination from in situ particle fluxes.  The location of this decay is also
organized by the detection of short spatial scales parallel and perpendicular
to the local magnetic field that are inferred directly from single point
measurements and force balance from the electron momentum equation.  This force
balance includes the full electron pressure tensor, the full three axis
electric and magnetic field measurements and the vectorial electron fluid
velocity, density and temperature tensor.  We illustrate sharp lower bounds to
the appropriately scaled dimensionless scale lengths perpendicular and parallel
to the magnetic field that occur with the most intense episodes of decay of the
electromagnetic energy density.  These ``endpoint'' scalings in terms of beta
modified ion inertial length and electron inertial length are in accord with
the organization of scales suggested by the formal ordering of the equations of
collisionless reconnection as summarized by Vasyliunas (1975).  The short
scales inferred from force balance are also required by an independent analysis
that examines the implied scales from Ampere's equation using the magnetic
field and the observed current density.  The Hall and ambipolar terms of the
Genearlized Ohm's Law are extremelly important in this region, where the
electron pressure gradient drifts are observed to significantly exceed the
electric drift.  This observation in this region is also expected from hybrid
and two fluid codes of collisionless reconnection.  Large parallel Alfven mach
number electron flows will also be documented along the separatrix defines by
strong signed electron heat flows as have also been reported in the hybrid,
fluid and particle particle simulations of reconnection.

"Electromagnetic Waves From 0.1 to 4 Hz Observed by Polar in the Magnetosphere, High-altitude Cusp, and Polar Cap", C T Russell, C A, Cattell, and S A Fuselier

Polar comparisons of solitary wave characteristics in the auroral zone, the plasma sheet boundary and the high altitude cusp and their relationship to particle distributions", C. A. Cattell, J. Dombeck, F. Mozer, M. Temerin, C. Kletzing, R. Pfaff and W. Peterson

Observations of Intense Electric Field Structures at the May 4, 1998
Magnetopause

Wygant, J R, School of Physics and Astronomy, University of Minnesota
Cattell, C A, School of Physics and Astronomy, University of Minnesota
Keiling, A, School of Physics and Astronomy, University of Minnesota
Mozer, F, Space Sciences Lab, University of California
Temerin, M, Space Sciences Lab, University of California
Peterson, W K, Lockheed-Martin Palo Alto Research Lab
Trattner, K, Lockheed-Martin Palo Alto Research Lab
Scudder, J, Department of Physics, University of Iowa
Russell, C T, IGPP-UCLA

                                    SM32C-02

Electric fields, magnetic fields, and particle measurements are presented from
a sequence of dayside magnetopause crossings observed by the POLAR spacecraft
during a strong compression of the earth's magnetopause on May 4, 1998 between
5:41 UT and 8:00 UT at 5.3 to 8.0 Re geocentric distance.  The electric fields
observed during this period are amongthe most intense ever observed in the
outer magnetosphere and are 1-2 orders of magnitude larger than those typically
observed at the magnetopause.  They ranged in magnitude up to 250 mV/m and were
directed predominantly normal to the direction of the nominal magnetopause
surface with both transient and steady state components.  The z GSM component
of the magnetic field varied from about -300 nT in the magnetosheath to 300 nT
in the magnetosphere with a transition characteristic of a rotational
discontinuity.  The steady state component of the electric field signature is
consistent with a boundary layer ExB flows in the magneto-sheath which are
tangential to the boundary and directed east ward with a magnitude of 500-1000
km/s.  Superimposed on these steady state signatures are intense transient
electric and magnetic field pulses lasting periods of about 1 second observed
in and near the magnetopause current layer.  These pulses have electric field
amplitudes >100 mV/m directed normal to the magnetopause surface and magnetic
field perturbations of >100 nT directed approximately transverse to the ambient
field.  Magnetic minimum variance analysis indicates the direction of the k
vector is well determined for a signficiant portion number of the pulses and in
these cases is directed along the magnetopause normal.  This implies the
dominate electric field signature is aligned along the k vector and is the
electrostatic component of the rotational discontinuity. These discontinuities
coincide with 10% to 100% density depressions as inferred from high time
resolution measurements of the spacecraft potential.  The wave Poynting flux
associated with the largest Alfvenic discontinuities exceeds 10 ergs/cm**2s
and is directed northward along the ambient field.  This suggests the
possibility that wave Poynting flux may be a signficant portion of the total
energy flux radiated way from the reconnection region.

Driving Dayside Convection

Maynard, N C, Mission Research Corporation
Burke, W J, Air Force Research Laboratory
Pfaff, R F, Laboratory for Extraterrestrial Physics,
            Goddard Space Flight Center Greenbelt

                                   SM42A-14

Recent measurements from ground based facilities, sounding rockets and
satellites have been combined to investigate the influence of the IMF on
dayside convection patterns.  Results from a sounding rocket flown during a
period of northward IMF indicate that the dominant Bx component exerts a
significant influence on the resulting convection.  Detailed comparisons of the
IMF measurements by Wind with ionospheric electric field data from the sounding
rocket provide conclusive evidence that signals interacted with the
magnetosphere on time scales shorter than nominal lags.  Under the described
IMF conditions the antiparallel merging hypothesis of Crooker limits magnetic
merging to near the southern hemisphere cusp.  In fact, the rocket measurements
are consistent with northern hemisphere convection having been stirred by IMF
merging with closed field lines in the southern hemisphere, which added open
flux to both polar caps.  In order to accommodate the open flux changes,
subsequent expansions and contractions of the northern polar cap boundary, were
detected by the rocket.  Some implications of restricting merging locations to
antiparallel sites, based on this and other event studies, will be discussed.

Peterson, W K, Lockheed Martin ATC
Cladis, J, Lockheed Martin ATC
Lennartsson, O W, Lockheed Martin ATC
Collin, H L, Lockheed Martin ATC
Moore, T E, NASA Goddard Greenbelt
Russell, C T, IGPP UCLA
Kletzing, C A, Univ. of Iowa
Maynard, N C, Mission Research Corp
Lu, G, NCAR

                                  SA52A-01

At geocentric distances of 6 to 9 Re in the Earth's polar cap, state-of-the-art
instruments on the POLAR spacecraft have monitored beams of escaping oxygen and
other heavy ions for three years during solar minimum conditions.  The
densities of the observed O+ beams have varied from at or near the detection
thresholds of ~0.01 cm-3 to over 10 cm3.  The energies of the beams have varied
from a few volts to over 10 keV.  The physical (temporal) extent has varied
from small patches to uniform flow over the polar cap sampled by the POLAR
satellite.  In this report, we present observations from the TIMAS, TIDE,
HYDRA, MAG, and EFI instruments on the POLAR spacecraft for representative
quiet and disturbed events and show how data from these state-of-the-art
instruments combined with existing models can be used to deduce information
about the various processes responsible for escape and energization of O+ and
its transport into the magnetotail.

Chapman Conference: Magnetospheric Current Systems
January 11-13, 1999

FAST and Polar Observations of Field-Aligned Currents and Convection Electric Fields During ISTP CME Events

C A Cattell; K Sigsbee; A Bowser (School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455; ph. 612-626-8918; fax 612-626-2029; e-mail: cattell@belka.space.umn.edu ; W Peria, C W Carlson, M Temerin, J McFadden, R Ergun, F S Mozer (Space Sciences Lab, University of California, Berkeley, CA 94720); R Strangeway, G Le, C T Russell (IGPP, University of California, Los Angeles, CA 90024); R Elphic (LANL, Los Alamos, NM 87544)

Many CME events, observed by the ISTP spacecraft, have been the subject of intensive study. In this talk, we will describe the evolution of field-aligned currents and convection electric fields observed by the FAST satellite during these events. During the January 6 - 11, 1997 event, FAST was in a noon-midnight orbit and, therefore, in a good local time sector to observe changes in the current system and polar cap boundary locations associated with the variations in the solar wind conditions. Dramatic variations in the intensity and structure of the currents and the electric field were observed. Other local time sectors are covered by later events. The low altitude FAST results will be compared Polar observations of currents and convection electric fields, at both low altitudes and high altitudes. The significance of the observations to our understanding of the dynamics of the magnetosphere and solar wind-magnetospheric and ionospheric-magnetospheric coupling during these events will be discussed.

A Statistical Study of Solitary Waves Using Polar Spacecraft Data
 
J.P. Crumley, C. A. Cattell, R. L. Lysak, J. P. Dombeck,
W. K. Peterson, H.A. Collin, C. A. Kletzing
 
Solitary waves are discrete non-linear wave structures that have 
been observed in many regions of the magnetosphere. In this study
we will present a statistical analysis of solitary waves.
Results from Polar spacecraft electric field waveform capture
bursts for more than a year of data will be presented, with
emphasis on bursts in the auroral upward current region where ion
beams are typically observed. This study will include analysis of
the occurrence frequency of solitary waves in bursts 
and of the geographic distribution of solitary wave 
occurrences.  The plasma conditions, including particle
composition and distributions, will be examined for bursts
containing solitary waves.  The features of the solitary waves 
themselves, including propagation speed, potential amplitude, net
potential, and structure size, will be examined both within given
bursts and across the entire statistical sample of solitary
waves.   These observations will be compared to the results
expected from theories on solitary waves and for the solitary
waves in ion beam regions comparisons will also be made to our
latest simulation results from ES2, a 2D3V electrostatic particle 
simulation.

Polar Observations of Solitary Waves at the Earth¹s Magnetopause

J. Dombeck ,C. Cattell, J. Crumley, , J. Wygant
School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455
C. A. Kletzing
Department of Physics and Astronomy, University of Iowa, Iowa City, IA  52242  USA 
W. K. Peterson
Lockheed Martin ATC, Palo Alto, CA   94304
F.S. Mozer
Space Sciences Laboratory, University of California, Berkeley, CA 94720

Using Polar 3d electric field data at the subsolar, equatorial magnetopause, 
solitary waves have, for the first time, been identified at the magnetopause.
 These nonlinear, bipolar electric field pulses parallel to the magnetic 
field occur both as individual spikes and as trains of spikes. The solitary 
waves have amplitudes up to ~25 mV/m, and velocities from ~150 km/s to 
>2500 km/s, with scale sizes the order of a kilometer (comparable to the 
Debye length). Almost all the observed solitary waves are positive potential 
structures with potentials of ~0.1 to 5 Volts. They are often associated 
with very large amplitude waves in either or both the electric and magnetic 
fields. Solitary waves have been observed at almost all magnetopause 
crossings at which a waveform capture was obtained.  Although most of the 
observed signatures are consistent with an electron hole mode, the events 
with very low velocities and the few negative potential structures may be 
indicative of a second type of solitary wave in the magnetopause current 
layer. The solitary waves may be an important source of dissipation and 
diffusion at the magnetopause.

Statistical Study of Fundamental Standing Alfven Waves Observed
by the Polar Satellite near the Subsolar Magnetic Meridian
 
K.-H. Kim, C. A. Cattell, J. R. Wygant, N. Lin, K. Takahashi, D.-H. Lee
 
In March and April 2001, the apogee (9 Re) of the Polar satellite 
was located near the subsolar magnetopause with its orbital plane
nearly parallel to a magnetic meridian plane.  Polar electric and
magnetic field data acquired during the two-month interval have 
been used to study fundamental standing Alfven waves near the subsolar
meridian plane (magnetic local time = 1000-1400) at magnetic latitudes
from the equator to 45 degrees and at L values between 7 and 12.
In the frequency band from 1.5 to 10 mHz, fundamental mode oscillations
were identified based on high coherence ( > 0.7) and an approximately
90-degree phase shift between the azimuthal magnetic and radial
electric field components.  Latitudinal variation of the relative
amplitude of E and B field and L dependence of the fundamental
frequencies are studied and compared with model calculations.
We also compare the plasma densities estimated from the Alfven wave
frequency and from Polar spacecraft potential.

Greenbelt, MD 20771; 301-286-6328; email pfaff@gsfc.nasa.gov

NATO Advanced Study Institute on Polar Cap Boundary Phenomena,
Longyearbyen, Svalbard, Norway, 4-13 June 1997

Invited oral paper: Polar observations of cusp electrodynamics:
Evolution from 2- to 4-cell convection patterns, by N. C. Maynard et al.

Presented 8 Aug 1997 at IAGA congress in Uppsala, Sweden. (Session 3.06)

Large amplitude ULF waves as Observed by the Polar satellite

J H Clemmons, R F Pfaff (NASA/Goddard Space Flight Center, Mail Code 696, Greenbelt, MD 20771 USA)

H J Singer (NOAA/Space Environment Center, Boulder, CO USA)

F S Mozer (Space Sciences Laboratory, University of California, Berkeley, CA 94720 USA)

C T Russell (Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095 USA)

J Scudder (University of Iowa, Iowa City, IA USA)

W K Peterson (Lockheed Martin Space Physics Laboratory, Palo Alto, CA 94304 USA)

The Polar satellite has accumulated a large number of observations of ULF waves during its year in orbit. The present work reports on a study of events selected for their large-amplitude excursions in the electric field, as measured by the Electric Field Instrument. In particular, Pc5 waves with amplitudes of 5 mV/m and above are included, with special emphasis on the extremely large (> 10 mV/m) waves observed during the magnetic cloud event of 10-11 January 1997. The waves are apparent in particle signatures as well as the fields measurements, so the local plasma environment can be well-characterized. The primary focus of the study is the exchange of energy between the fields and the particles.

Presented at IAGA 1997

Coordinated ISTP statistical study of electric field coupling between the solar wind and the magnetosphere

Turner, N. E., D. N. Baker, T. I. Pulkkinen, H. J. Singer, N. Maynard, F. Mozer, R. P. Lepping, K. Ogilvie, T. A. Fritz, and T. Mukai

Chapman Conference on Magnetospheric Current Systems, Kona, January , 1999.

FAST and Polar Observations of Field-Aligned Currents and Convection Electric Fields During ISTP CME Events,

C A Cattell, K Sigsbee, A Bowser, W Peria, C W Carlson, M Temerin, J McFadden, R Ergun, F S Mozer, R Strangeway, G Le, C T Russell, R Elphic,

IUGG meeting in July, 1999 Birmingham, England

FAST AND POLAR OBSERVATIONS OF THE POLAR CAP BOUNDARY, FIELD-ALIGNED CURRENTS AND CONVECTION ELECTRIC FIELDS DURING CME EVENTS

FAST AND POLAR OBSERVATIONS OF THE POLAR CAP BOUNDARY, FIELD-ALIGNED CURRENTS AND CONVECTION ELECTRIC FIELDS DURING CME EVENTS

CYNTHIA CATTELL, A. Bowser, C. McBrady, K. Sigsbee and J. Wygant (School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA, Email: cattell@belka.space.umn.edu)

C. Carlson, R. Ergun, J. McFadden, F. Mozer, W. Peria (Space Sciences Lab, University of California, Berkeley, CA 94720, USA)

G. Le, C. Russell, R. Strangeway (IGPP, University of California, Los Angeles, CA, USA)

R. Elphic (Los Alamos National Lab, Los Alamos, NM 87545, USA)

M. Brittnacher and G. Parks (Geophysics Program, University of Washington, Seattle, WA 98195, USA)

There have been many CME encounters with the earth’s magnetosphere since the launch of FAST in August, 1996. The short orbital period and data coverage for almost every auroral zone crossing allow us to determine the changes in field-aligned currents, convection electric fields and particle boundaries with time to determine the effects of solar wind plasma and magnetic field properties. In this paper, we present observations of the polar cap boundary as determined from four different methods-convection reversal, location of field-aligned currents, particle signatures and optical signatures from the Polar UVI imager. In addition, observations of field-aligned currents and convection electric fields from Polar perigee passes will be used to provide auxiliary observations which, for most events, are at different local times than the FAST observations. The resulting polar cap sizes will be compared to solar wind parameters observed by WIND. This results of this study will enhance our understanding of the coupling of the solar wind and the magnetosphere during CME events. The comparison of multiple techniques to determine the polar cap boundary will aid in estimating the accuracy of these methods for different local times and levels of activity.