ISTP NEWSLETTER Vol 6, No. 3. December, 1996



Figure shows a schematic representation of the geometry suggested by the preliminary analysis of an ISTP Correlative Science Event.


Title Author

ISTP moves to CDF V2.5 - Mona Kessel

ISTP Shines at the Fall 96 AGU Meeting - Mauricio Peredo

New NSSDC User Survey - Joe King

A multispacecraft ISTP Study: substorm evolution from the solar wind to the magnetosphere and ionosphere - T. I. Pulkkinen,D. N. Baker, N. Turner, H. J. Singer, J. B. Blake, H. Spence L. A. Frank, J. B. Sigwarth, T. Mukai, S. Kokubun, R. Nakamura C. T. Russell, H. Kawano, F. Mozer, J. A. Slavin, R. Lepping R. Anderson, G. Reeves, L. M. Zelenyi

Case Study for Theory-Data Closure - Mauricio Peredo

ISTP Correlative Science Event - Mauricio Peredo

New Release of the ISTP Key Parameter Visualization Tool (KPVT), (Version 2.1 will be officially released on 12-2-96) - Syau-Yun Hsieh, Mauricio Peredo, Bill Mish

Polar/ISTP Science Coordination - Nicola J. Fox, Robert A. Hoffman


Michael Cassidy

Contributing Editors:

Steven Curtis - Science Editor

Doug Newlon - Data Distribution Facility

Kevin Mangum - Central Data Handling Facility

Dr. Mauricio Peredo - Science Planning and Operations Facility

Dick Schneider - ISTP Project Office

Jim Willett - NASA Headquarters

ISTP moves to CDF V2.5

Mona Kessel

ISTP has adopted CDF V2.5 as the official project version; the previous official version was CDF V2.4. With the installation of CDHF software version 6.4 (approximately December 1996), CDF V2.5 will be producing the Key Parameter files from Geotail, Wind, and Polar. It will be necessary to upgrade your system to CDF V2.5 in order to read the newly created KP files.

ISTP has tried to minimize software changes to lessen the impact on the PI/CoI community. This change is necessary in order to verify externally generated CDFs, many of which are using CDF V2.5.

CDF V2.6 has been released by NSSDC, however at this time IDL is not supporting this version and so it's use is not yet recommended. (CDF V2.6 has a number of enhancements which are highly desired, for example: compression. These will be discussed in a future newsletter article.) IDL support for CDF V2.6 is expected with one of their upcoming releases next year. After that time ISTP will adopt CDF V2.6

as the official version and use it for producing Key Parameter files.

There is a user support office for CDF that you should contact when you need assistance.

For Email requests send to:


Mona Kessel
Goddard Space Flight Center
Code 632.0
Greenbelt, Md. 20771

ISTP Shines at the Fall 96 AGU Meeting
Mauricio Peredo

Over the last few years, several special sessions have been organized at AGU meetings with the purpose of highlighting ISTP activities. Initially, these sessions described the ISTP data system as well as existing or planned data products of interest to the wider space physics community. More recently, the special sessions have focused on presentation of early ISTP results; primarly those involving correlative studies between different spacecraft observations, ground-based measurements, or theoretical investigations.

This December, the tradition continues with a series of ISTP sessions at the Fall 96 AGU. In fact, following the successful launches of SOHO, POLAR, FAST and Interball-Aurora, many collaborations have ensued, resulting in in overwhelming number of ISTP-related papers to be presented. The

specific sessions focusing on ISTP correlative results this year span the entire spectrum of solar, interplanetary, magnetospheric and ionospheric physics. Specifically, the follwing sessions have been


SM71A Sun-Earth Connections: ISTP/GGS Correlative Results I: MagnetosheathPosters (joint with SA,SH)

SM72F Sun-Earth Connections: ISTP/GGS Correlative Results I: Magnetosheath (joint with SA,SH

SM11A Sun-Earth Connections: ISTP/GGS Correlative Results II:Polar Cap and LobesPosters (joint with SA,SH)

SM12C Sun-Earth Connections: ISTP/GGS Correlative Studies II:Polar Cap and Lobes (joint with SA,SH)

SM21D Sun-Earth Connections: ISTP/GGS/POLAR Initial Results I (joint with SA,SH)

SM22B Sun-Earth Connections: ISTP/GGS/POLAR Initial Results II Posters

SM21A Sun-Earth Connections: ISTP/GGS Correlative Results III: Plasma Sheet and AuroraPosters (joint with SA,SH)

SM22D Sun-Earth Connections: ISTP/GGS Correlative Results III: Plasma Sheet and Aurora (joint with SA,SH)

SM31A Sun-Earth Connections: ISTP/GGS Correlative Results IV: Inner Magnetosphere and FAST Posters (joint with SA,SH)

SM32D Sun-Earth Connections: ISTP/GGS Correlative Results IV: Inner Magnetosphere and FAST (joint with SA,SH)

SM41A Sun-Earth Connections: ISTP/GGS Correlative Results V: Theory and Ground Based Observations Posters (joint with SA,SH)

SM42C Sun-Earth Connections: ISTP/GGS Correlative Results V: Theory and Ground Based Observations (joint with SA,SH)

SH71B Global Coronal Disturbances and Mass Ejections I

SH72B Global Coronal Disturbances and Mass Ejections II

SH11A Global Coronal Disturbances and Mass Ejections II Posters

SH21D Helioseismology I

SH22A Helioseismology II

SM41A Sun-Earth Connections: ISTP/GGS Correlative Results V: Theory and Ground Based

Observations Posters (joint with SA,SH)

SM42C Sun-Earth Connections: ISTP/GGS Correlative Results V: Theory and Ground Based Observations (joint with SA,SH)

SH71B Global Coronal Disturbances and Mass Ejections I

SH72B Global Coronal Disturbances and Mass Ejections II

SH11A Global Coronal Disturbances and Mass Ejections II Posters

SH21D Helioseismology I

SH22A Helioseismology II

The full program for the FALL 96 AGU Meeting, including session descriptions and paper titles for each session is available from the AGU world wide web site at URL: http://www.agu.org/meetings/fm96top.html/"

In addition to these 17 sessions, a large number of papers involving ISTP studies are scheduled for other sessions. All together, the FALL 96 AGU will see well over 250 presentations reporting results from the ISTP initiative.

Mauricio Peredo
ISTP Science Planning and Operations Facility,
Raytheon STX Corporation
Goddard Space Flight Center
Greenbelt, Md. 20771

New NSSDC User Survey

Joe King

The National Space Science Data Center has initiated a new survey of present and potential users of NSSDC data and services. The survey solicits both user satisfaction levels and suggestions for changes in its services and interfaces which would make NSSDC more effective and useful. This announcement earnestly solicits your input. The survey is at URL: http://nssdc.gsfc.nasa.gov/nssdc/survey.html/

Joseph H. King
Goddard Space Flight Center
Code 633.0, NSSDC
Greenbelt, Md. 20771

A multispacecraft ISTP Study: substorm evolution from the solar wind to the magnetosphere and ionosphere

T. I. Pulkkinen(1,2), D. N. Baker(1), N. Turner(1), H. J. Singer(3),
J. B. Blake(4), H. Spence(5), L. A. Frank(6), J. B. Sigwarth(6),
T. Mukai(7), S. Kokubun(8), R. Nakamura(8) C. T. Russell(9),
H. Kawano(9), F. Mozer(10), J. A. Slavin(11), R. Lepping(11),
R. Anderson(6), G. Reeves(12), and L. M. Zelenyi(13)

(1)Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO
(2)Permanently at: Finnish Meteorological Institute, Helsinki, Finland
(3)NOAA Space Environment Center, Boulder, CO
(4)The Aerospace Corporation, Los Angeles, CA
(5)Department of Astronomy, Boston University, Boston, MA
(6)Department of Physics and Astronomy, The University of Iowa, Iowa City, IA
(7)Institute of Space and Astronautical Science, Sagamihara, Japan
(8)Solar Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Japan
(9)Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, CA
(10)Space Science Laboratory, University of California Berkeley, Berkeley, CA
(11)NASA Goddard Space Flight Center, Greenbelt, MD
(12)Los Alamos National Laboratory, Los Alamos, NM
(13)Space Research Institute (IKI), Moscow, Russia


An isolated substorm event on May 15, 1996, was recorded by an unprecedented suite of satellites both in the solar wind and in the magnetosphere. We show data from various instruments onboard several ISTP satellites to discuss both the prompt response of the dayside magnetosphere to the changes in the interplanetary magnetic field and the following substorm evolution in the nightside tail.

1. Introduction

Exploration of the Earth's space environment has revealed a dynamic and complex system of interacting plasmas, magnetic fields and electrical currents. The near-Earth environment has traditionally been explored and studied as a system of independent component parts - the interplanetary region, the magnetosphere, the ionosphere, and the upper atmosphere. From these early explorations, it was known that geospace is a complex system of highly interactive parts. One of the key objectives of the International Solar Terrestrial Physics program is to understand how the individual parts of the closely coupled, highly time-dependent geospace systems work together [e.g., Acuna et al., 1995] (see references therein for the instrumentation used here).

Magnetospheric substorms represent a basic form of interaction between the solar wind, the magnetosphere, and the ionosphere. One of the key open questions in magnetospheric dynamics is the coupling of the various plasma regions; how important it is for the dynamics and through what mechanisms is the information passed from the solar wind to the magnetosphere or between the magnetosphere and the ionosphere. Early case studies and statistical analyses led to the understanding that substorms occurred when the interplanetary magnetic field turned southward: that allowed a more direct energy input from the solar wind into the magnetosphere, which later led to the explosive energy release during the substorm expansion phase. However, the mechanism which initiates the energy release is still debated upon: both internal instabilities and external (solar wind and/or IMF induced) triggers have been suggested.

A key problem in substorm studies has been the lack of simultaneous observations from all the key regions: Early and mid 1980's hosted a variety of magnetospheric satellites, which led to a wealth of new information of the inner magnetosphere dynamics, but during that period the solar wind and IMF observations were not continuously available. Furthermore, the more advanced instrumentation onboard the presently operative satellites have revealed processes that were not possible to detect with previous spacecraft. Here we present data from one particularly well-observed substorm event using a multitude of satellites in the solar wind and in the magnetosphere together with ground-based observations of the ionospheric current systems.


Figure 1 Satellite locations in the GSM X-Y plane: (left) Larger view showing the upstream satellites. (right) Detailed view of the inner magnetosphere. The statistical location of the magnetopause is shown with the black line, the solar wind is indicated with blue, and magnetosphere with green.

The extensive set of observations here allows detailed study of the magnetospheric effects of changes in the interplanetary magnetic field (IMF), with three satellites (WIND, IMP-8, and INTERBALL Tail Probe) upstream and POLAR in the dayside high-latitude polar region. Furthermore, we show the time evolution of the instability growth in the nightside magnetosphere using geostationary satellites and GEOTAIL at about 10 Re radial distance.

2. Observations

2.1 Solar wind - magnetosphere coupling

The top panel of Figure 2 shows the IMF Bz measured by IMP-8, WIND, and INTERBALL, all upstream of the Earth. Using magnetic field and solar wind speed measurements allowed us to infer that the southward turning, which is a sign of enhanced coupling between the solar wind and the magnetosphere, arrived at the magnetopause at about 0548 UT. Similarly, the northward turning recorded by WIND at about 0652 UT arrived at the magnetopause at about 0705-0707 UT.

POLAR was located near local noon, moving poleward through the auroral region. Figure 3 shows the energetic electron and ion data from the CEPPAD instrument from 0500 UT until 0700 UT. Interestingly, the higher-energy electrons (top panel) disappear from the detector at about the time of the southward turning of the IMF. (The lower-energy portion of the electron data shown as white and

red should be considered as a low energy threshold of the instrument.) Between 0600 and 0610 UT the satellite was at the dayside auroral oval region, moving from the closed field lines to the open field line environment.

Immediately upon the arrival of the southward turning of the IMF, the POLAR electric field instrument (EFI) showed a significant enhancement of the fluctuations in the DC electric field (third panel of Figure 2). The data indicate an increased level of activity throughout the period of negative IMF Bz, after which the field quieted substantially. The wave instrument (PWI) onboard POLAR (Figure 4) also detected increased electrostatic wave power at low frequencies (peak intensity below 100 Hz) beginning immediately after the southward turning of the IMF; the power level was enhanced until the IMF turned northward again.

The magnetic field measured by POLAR reveal that after 0550 UT POLAR crossed the auroral current systems. The field differences shown in the fourth panel of Figure 2 (model field values have been subtracted from the actual measurements) indicate that the field lines became more vertical. We interpret this change to be caused by the arrival of the front carrying the southward IMF at the dayside magnetopause. Note also that the field disturbances begin to decrease at the time of the northward turning of the IMF shortly after 0700 UT.

In summary, at the estimated time when the southward IMF arrived at the dayside magnetopause, several instruments onboard POLAR recorded an almost instantaneous response to the changed external conditions.


Figure 2 Panels from top to bottom: Interplanetary magnetic field Bz and Bx from WIND (blue), IMP 8 (green), INTERBALL (red) in GSM coordinates. Electric field from POLAR. Magnetic field from POLAR (in nT), the data are in GSM coordinates, and model field values have been subtracted from the observations.


Figure 3 Energetic electron and ion data from the POLAR CEPPAD instrument. The electron measurements below about 80 keV have not yet been calibrated, and the monoenergetic band at low energies should be considered as the low energy cutoff. The bottom panel shows POLAR L-value (solid line, scale on the left) and MLT (dashed line, scale on the right).

The solar wind and magnetosphere interact also in a slower time scale, of the order of few days. The top panel of Figure 5 shows an auroral image taken during the time interval discussed here. The continental outline has been added to the figure in order to help locating the band of auroral luminosity over the northern polar region and the auroral brightening occurring over North America. The bottom panel of Figure 5 shows the global extent of the outer radiation belt on 15 May 1996 in a northern hemisphere projection map. This map shows the count rate of electrons with E>1 MeV measured by SAMPEX as a function of geographic longitude and latitude. The bright red and yellow collar around the northern polar region shows that the outer radiation belt was rather intense as a result of a small solar wind stream that peaked on 13 May 1996. (Note that the bright red pattern near the bottom of the image is relatively constant and is due to the South Atlantic Anomaly). We are in the process of comparing the auroral luminosity pattern of location and intensity with the related pattern of radiation belt features for this period.

2.2 Substorm evolution

The GOES-8 and GOES-9 satellites at geostationary orbit [Singer et al., 1996] started recording substorm growth phase-associated signatures at 0600 UT: the field configuration became gradually more stretched (top two panels of Figure 6). Magnetic field and convective electric field values observed at GEOTAIL (bottom three panels of Figure 6) at about 10 Re distance reveal a similar picture, growth phase signatures began at about 0600 UT, and no prior disturbances that could be associated with the IMF southward turning were seen. Thus, it took about 10 min for the information of the dayside changes to penetrate to the nightside plasma sheet. The auroral pictures taken by the UVI imager onboard POLAR give a global view of the substorm evolution. Figure 5 shows a sample image taken during the second substorm activation at 0713 UT.

The Los Alamos National Laboratory satellite 1990-095 was in the local dawn sector at about 0500 MLT. It recorded dispersed electron signatures of three distinct activations (top panel of Figure 7). The

two GOES satellites were in the nightside tail, GOES-8 in the morning sector and GOES-9 in the evening sector; the actual substorm onset meridian was located between the spacecraft. Thus, we are able to follow the azimuthal expansion of the substorm-associated current systems in the nightside tail.

The GEOTAIL plasma moments (bottom panels of Figure 7) show the onset of Earthward flow and large electric field fluctuations at 0639 UT, a few minutes after a weak field dipolarization was seen at GOES-8 somewhat closer to midnight.

3. Discussion

With this complex set of data, we have examined three distinct events: a southward turning of the IMF; a substorm onset caused by an internal tail instability; and a substorm intensification occurring simultaneously with an IMF northward turning. The results, when fully analyzed, can reveal important facts about the solar wind - magnetosphere coupling and on the various substorm onset mechanisms.

The southward turning of the IMF caused an immediate response at the dayside auroral oval region. The nightside magnetosphere between 6 and 10 Re responded to the IMF turning within 10 minutes.


Figure 4 Wave measurements from POLAR PWI instrument showing the electric field wave power.


Figure 5a Auroral image taken by the FUV camera of the VIS imager onboard POLAR at 0713 UT, during the second substorm activation.


Figure 5b Radiation belts as measured by SAMPEX. The image shows a composite of measurements over one day (16 orbits), flux of electrons over 1 MeV energy are shown.

The observations suggest that some signature of the substorm onset is rapidly seen at various locations in the nightside tail: The geostationary orbit satellites remotely sensed the current wedge currents poleward of the s/c locations immediately after their formation. GEOTAIL toward dawn from the onset longitude recorded fluctuations in the magnetic and electric fields also within a minute of the onset, several minutes before Earthward flow and actual magnetic field dipolarization were observed at the satellite location. Thus, this demonstrates the truly global nature of the substorm process and the rapid way the magnetosphere transfers information from one location to another.

This article presents initial results of an ongoing study involving multiple spacecraft and ground-based observations: In the analysis, we have used observations from ten spacecraft:

Furthermore, ground-based magnetograms were studied from the 14 CANOPUS chain magnetometers, the 13 Greenland chain magnetometers, and several other locations in Eastern Canada (obtained through the online facility at NGDC), which was the key location of activity. Obviously, the results shown here represent only a very minor portion of the data gathered.

This study is a very positive demonstration of the capabilities of the ISTP Key Parameter and other WWW-based data search tools: These make it possible to take a quick initial look at the data and its availability. Furthermore, identifying key observations and dynamical events is much easier when the various data can be analyzed together in the key parameter format.

Already the initial results reveal the importance of having several spacecraft upstream of the magnetosphere for detailed investigation of the solar wind and IMF conditions before and during the substorm activity. Similarly, good coverage is necessary both in the dayside magnetosphere as well as in the magnetotail in order to address questions related to the channels of information transfer from the solar wind to the magnetosphere. It is necessary that these processes be understood before detailed mechanisms for the substorm onset can be conclusively evaluated.


Figure 6 Panels from top to bottom: Magnetic field Bz from GOES-8 and GOES-9. Magnetic field By from GOES-8 and GOES-9. Total magnetic field, and magnetic field Bz and Bx components from GEOTAIL. Convection electric field (computed from magnetic field and plasma measurements) Ey component.


Figure 7 Panels from top to bottom: Electron differential fluxes from s/c 1990 -095. Plasma velocity Vx and Vy components measured by GEOTAIL LEP instrument. Convection electric field Ex and Ez components as computed from plasma and magnetic field measurements.


We thank the NSSDC personnel for maintaining the online ISTP key parameter facility. The work of TP was supported by the Finnish Fulbright Commission. We are thankful for the ISTP teams for their support for this study. The plasma wave data from POLAR PWI instrument was kindly provided by D. Gurnett (instrument PI). We thank Y. Saito for evaluation of the GEOTAIL LEP data, and ISAS for successful and continuing operations of GEOTAIL. We thank S. Romanof for providing the INTERBALL magnetometer data to the key parameter facility, and the IKI group for maintaining the INTERBALL key parameter data set. We thank Terry Raytheon and the Canadian Space Agency for providing the CANOPUS data and Eigil Friis-Christensen for providing the Greenland magnetometer data.


Acuna, M. H., K. W. Ogilvie, D. N. Baker, S. A. Curtis,
D. H. Fairfield, and W. H. Mish, The global geospace science program
and its investigations, in: C. T. Russell (ed.), The global geospace
mission, Kluwer Academic Publishers, Dordrecht, the Netherlands, p. 5,

Singer, H. J., L. Matheson, R. Grubb, A Newman, and S. D. Bouwer,
Monitoring space weather with the GOES magnetometers, SPIE Conference
Proceedings, Volume 2812, 4-9, August 1996, in press.

Case Study for Theory-Data Closure
Mauricio Peredo


A key goal of the ISTP initiative is to understand the flow of mass, momentum and energy across the solar wind-magnetosphere-ionosphere system in a global sense.


Following the successful launch of POLAR on February 24, 1996, a detailed end-to-end test involving the spaceborne, theory and ground-based investigations comprising ISTP became possible.


The ISTP Science Planning adn Operations Facility was chartered by the Science Working Team to identify candidate intervals for such an end-to-end test.


The desired selection constraints, in approximate priority order, were: