ISTP NEWSLETTER Vol 6, No. 1. Feb, 1996

http://pwg.gsfc.nasa.gov/istp/newsletter.html

istp-logo

movie1
ISTP/GGS Movie of the Magnetic Cloud Event of October 18-20, 1995


IN THIS ISSUE

Title Author

ISTP/GGS Movie of the Magnetic Cloud Event of October 18-20, 1995 - S. Boardsen

ISTP Ground-Data System Response to a Science Event - W. Mish

The International Auroral Study - M. Teague

The 210 degree Magnetic Meridian Observation Project and GGS - M. Teague

The Heliospheric Current Sheet: Comparisons of a Solar Surface Model with Observations at 1 AU from WIND Magnetic Field Data at Solar Minimum - R. P. Lepping

IACG First Campaign Update and the SM05 Session at the Spring AGU - J. Green

Space Physics Catalog (SPyCAT) Access To NSSDC/SPDF Nearline Data - E. Greene

A new-generation global magnetosphere field model, based on spacecraft magnetometer data - N. A. Tsyganenko

Public Release of ISTP Key Parameter Data - R. Kessel

SOHO Joins ISTP Mission - M. A. Calabrese

New Location for the ISTP/SPOF Web server - M. Peredo

Satellite Situation Center Releases V.2.2 of SSC Software - R. McGuire

Near-Real-Time Server, an Enhancement to the Central Data Handling Facility (CDHF) Near- Real-Time (NRT) Subsystem - D. Schneider

Editor:

Michael Cassidy
CASSIDY@ISTP1.GSFC.NASA.GOV

Contributing Editors:

Steven Curtis - Science Editor
U5SAC@LEPVAX.GSFC.NASA.GOV

Doug Newlon - Data Distribution
NEWLON@IPDGW1.NASCOM.NASA.GOV

Kevin Mangum - Central Data Handling Facility
MANGUM@ISTP1.GSFC.NASA.GOV

Dr. Mauricio Peredo - Science Planning and Operations Facility
PEREDO@ISTP1.GSFC.NASA.GOV

Dick Schneider - ISTP Project Office
SCHNEIDER@ISTP1.GSFC.NASA.GOV

Jim Willett - NASA Headquarters
WILLETT@USRA.EDU


ISTP/GGS Movie of the Magnetic Cloud Event October 18-20, 1995

Scott Boardsen and Mauricio Peredo
Gordon Rostoker and Hamid al Nashi

On October 18 at approximately 19:50 UT the Earth was engulfed by a magnetic cloud traveling away from the Sun at approximately 370 km/s. It took approximately 30 hrs for the Cloud to pass through the Earth's geospace. Magnetic clouds are believed to be magnetic flux ropes expanding away from the Sun, whose ends are tied to the Sun's surface. They are characterized by strong smoothly varying magnetic fields when compared to the nominal magnetic field carried by the solar wind which is highly fluctuating and about a factor of 5 smaller in magnitude. Low proton temperature is also associated with magnetic clouds. Often they exhibit a strong bipolar signature in the north/south component (Bz) of the Interplanetary Magnetic Field (IMF). When this strong north/south bipolar signature occurs, clouds can trigger magnetic storms and substorms during the southward (negative Bz) phase of the cloud passage. Strong geomagnetic activity produced by clouds can cause brilliant auroral displays (the "Northern Lights"), surges in power lines, communication problems ( "white outs") and other geophysically related phenomena.

Figure 1
movie1_icon

A Quicktime movie illustrating the passage of this magnetic cloud has been created and can be found on the world wide web at http://iacq.org/~galiardi/iacq/campaign_1/guest/cloud_movies.html ; and a limited number of video copies can be obtained from the authors. This movie illustrates the strong interaction between a magnetic cloud and the Earth's geospace. Geospace is the region of space influenced by the Earth's magnetic field; it includes the Earth's atmosphere, ionosphere, and the region of space extending from the ionosphere out to the Earth's bowshock. Figure 1 shows the cloud passage just before it's encounter with Earth's geospace and Figure 2 shows the cloud passage near the height of auroral activity. The elements of each frame consist of the following; 1) (upper left panel) time label, 2) (upper middle panel) Cartoon of the Cloud propagating away from the Sun, 3) (upper right panel) The Earth's auroral oval, 4) (lower left panel) a bar chart which indicates the solar wind pressure and IMF Bz component near the Earth, 5) (lower right panel) the solar wind propagating toward the Earth and interacting with the Earth's bow shock and magnetopause. The magnetopause (the boundary between the magnetic fields of the Earth and the Sun) is an obstacle to the passage of the solar wind, and the bow shock develops to deflect the solar wind around it. (Note: the magnetic cloud is emitted from the Sun's surface approximately 3 days earlier than depicted in the cartoon.)

Figure 2
movie2_icon

The purpose of the Solar Wind panel (lower right panel) is to give the viewer a feeling of what's coming. The panel shows the solar wind propagating toward Earth beginning at 150 RE (Earth radii) upstream and away from the Earth down to -50 RE downstream . The arrows represent the Bz component of the IMF, up (green) for Northward and down (red) for Southwad. The pressure is color coded to two gray levels, the brighter level corresponds to pressure greater than 5 nPa. The two curves around the Earth are respectively, the bowshock ( furthest from the Earth) and the magnetopause (closest to the Earth). The bowshock (Fairfield model) and magnetopause (Petrinec-Russell model) are determined from the solar wind pressure and IMF data measured by the WIND spacecraft. The WIND spacecraft was located at 175 RE upstream of the Earth, so roughly 50 minutes is required for the solar wind signal detected by WIND to reach the Earth's geospace. The viewer should note how the magnetopause contracts and flares as the IMF and pressure change.

The auroral oval panel (upper right panel) shows the viewer how the Earth's geomagnetic activity responds to the Solar Wind impinging on the Earth's geospace. The auroral oval is an oval shaped band that surrounds the Earth's magnetic poles where electrons, accelerated in the Earth's magnetosphere, spiral down the Earth's magnetic field lines striking and depositing energy into the upper atmosphere. Some of this energy is released as light from excited atoms causing the auroral oval to glow. The location of the auroral oval for this movie was determined from measurements made by the Canopus Fort Churchill Line of Magnetometers (depicted by the row of white dots on the Earth's surface) . The magnetometer data are used to deduce the position of the oval at one longitude, from which the entire oval is reconstructed from a statistical model developed by Rostoker and Phan (JGR,91,1716,1986). The poleward edge of the auroral oval defines the polar cap, a region where the Earth's magnetic field lines are connected to the Sun's magnetic field lines and swept back by the solar wind towards the Earth's geomagnetic tail. The size of the polar cap indicates of the amount of energy stored in the Earth's geomagnetic tail, and the intensity of the oval indicates the rate at which this stored energy is being dissipated into the Earth's ionosphere.

Key features to look for during the play of the movie:

Three versions of the cloud movie (Quicktime format) are available for viewing:
Movie at 5 min resolution (9.2MB)
Movie at 15 min resolution (3.2 MB)
Movie at 30 min resolution (1.7 MB)

M. Peredo
Raytheon STX
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
(301) 286-1526
peredo@istp1.gsfc.nasa.gov

S. Boardsen
Raytheon STX
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
(301) 286-0837
boardsen@nssdca.gsfc.nasa.gov

G. Rostoker
Canadian Network for Space Research and
Department of Physics
University of Alberta
Edmonton, Alberta, Canada T6G 2J1
rostoker@space.ualberta.ca

H. Nashi
Canadian Network for Space Research and
and Department of Physics
University of Alberta
Edmonton, Alberta, Canada T6G 2J1
hamid@space.ualberta.ca


ISTP Ground-Data System Response to a Science Event

M. Peredo, S. Boardsen, W. Mish

cloud_icon

A magnetic cloud arrived at Wind at approximately 19 UT on Oct 18, 1995. The magnetic field direction was observed to turn southward abruptly when WIND entered the magnetic cloud, and the magnetic field rotated gradually to a northward orientation over the course of approximately 30 hours as the magnetic cloud moved past the spacecraft. The magnetic field was strong inside the magnetic cloud, thus generating strong magnetic disturbances and spectacular auroral displays on the ground.

In this communcation, we outline the response of the ISTP ground-data system to the event, with particular emphasis on how it allowed the science teams to quickly put together a picture of what had occurred. The story highlights the collaboration between the ISTP project, the Air Force and the Space Environment Lab with near-real-time data that allows space weather monitoring. Furthermore, the value of Key Paramter data was clearly demonstrated, as they provided quick access to the key observations required to characterize the event. In addition, the rapid response by the ground-data system allowed not only quick access to Key Parameter data, but also supported dissemination of information on the event to the press, and access to the general public via the world wide web. A complete manuscript reporting on initial analysis of the event was completed and submitted for publication in less than one month! After many years of planning and hard work, it is a pleasure to see the efforts have paid of; the ISTP ground data system is fully operational, and providing outstanding support to the ISTP science community. Table 1 below, provides a timeline of activities associated with the event.

Table 1. Timeline of Cloud Event Activities

Oct/Nov                         Activities

18        SEL officials call ISTP project to verify validity 
          of observed values in near-real-time data.
19        SPOF reviews Key Parameter data available on the 
          CDHF; instrument anomalies are ruled out via 
          discussion with investigators.
20-22     SPOF reviews additional Key Parameter data and 
          magnetograms off web pages from various ground-based 
          investigations, and notifies ISTP Project Scientists. 
          Event is "tentatively" identified as a 
          magnetic cloud.
23-25     Event is presented at Geotail SWG and IACG decides to 
          extend Interval #1 of the First IACG Science Campaign 
          so as to include the cloud period.
27        A press-release on the event is drafted by the ISTP 
          Project Scientist and submitted to NASA Public Affairs.
23-3      SPOF and SPDF jointly set up web pages describing the 
          event and providing pre-generated summary plots and 
          interactive plotting/data access for all ISTP Key 
          Parameter data for the event.
3         SPOF and SPDF develop a movie illustrating the magnetic 
          cloud and its effect on Earth, using observations from 
          WIND and CANOPUS.
6         NASA Press-Release on the event appears prompting 
          extensive interest by the Associated Press.
8         An eyewitness account of the auroral displays associated 
          with the event is received in response to the web 
          announcement of the cloud.
15        A manuscript detailing preliminary analysis of the cloud 
          topology and characteristics is submitted for the special 
          GRL issue on Wind results. 
20        The BBC Horizon Program and The Discovery Channel request
          copies of the cloud movie

A description of the cloud event is available on the world wide web, at URL http://bolero.gsfc.nasa.gov/~solart/cloud/cloud.html

Acknowledgment:

Clearly, a large number of individuals are responsible for the successful operation of the ISTP Ground -Data system. On behalf of the ISTP project, we thank all current and past members of the various facilities for their efforts.

M. Peredo
Raytheon STX
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
(301) 286-1526
peredo@istp1.gsfc.nasa.gov

S. Boardsen
Raytheon STX
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
(301) 286-0837
boardsen@nssdca.gsfc.nasa.gov

W. Mish
NASA
Goddard Space Flight Center
Mailstop 694.0
Greenbelt.Md. 20771
wmish@istp1.gsfc.nasa.gov


The International Auroral Study

Michael Teague, Cindy Cattell

In July 1993, the International Steering Committee for the Solar Terrestrial Energy Program (STEP) approved the establishment of the International Auroral Study (IAS) as STEP Project 2.6. The intent of the IAS is to make an intense study of the Northern and Southern Aurorae using coordinated space based and ground-based observations as well as aircraft and rocket observations. The original intent was that the first campaign interval for the Northern Aurora would be December 1995 through March 1996. However, delays in the launch of key spacecraft such as FAST, POLAR and MSX have delayed the campaign. Since it now appears that these, and other important, spacecraft will be launched in 1996, the first campaign interval is now planned for December 1996 through March 1997. We anticipate that there will be 15-20 time periods of approximately 1 hour duration within this broad interval when it will be possible to make multiple observations of the Northern Aurora.

The goal of the IAS is to characterize as completely as possible the formation of the aurora, including the study of topics such as the relationship of the structure and dynamics of visible arcs to in situ measurements of acceleration processes. The IAS will also characterize the large-scale properties of the electric fields and current systems in the ionosphere, and determine the association of auroral arcs with magnetospheric substorms and various boundaries in the magnetosphere.

In order to achieve the IAS goals, both ground-based and in-situ experimental data will be needed, as well as theoretical and numerical modeling. It is anticipated that the ground-based, aircraft and rocket data will include the following:

The spacecraft data expected to contribute to the IAS may be divided between remote sensing (with respect to the aurora) and in situ measurements. The remote-sensing data will consist of:

The in-situ measurements will be lead by the comprehensive auroral spacecraft such as FAST. In addition, POLAR, CLUSTER, GEOTAIL and INTERBALL fields and particle observations will directly contribute to the IAS database.

The Project Leader for the IAS is Cindy Cattell ( cattell@belka.spa.umn.edu ) and the Project team includes scientists from the U.S., Europe, Japan, Russia and Australia. The campaign coordinators are Cindy Cattell and Michael Teague ( teague@nssdca.gsfc.nasa.gov ).

WWW pages have been established for the IAS at URL: http://bolero.gsfc.nasa.gov/ias/ias.html . At present these pages include a project description, and address information for the project team, campaign coordinators and campaign participants (approximately 120 at present). The pages also include a list of the participants' interest areas, observation programs etc. and an automatic form is included for new participants. Please "sign-up" if you have interest in participating in the campaign. Also included at present are references to the various spacecraft, rocket, aircraft and ground-based programs potentially involved in the IAS. In the future, as reliable trajectory information becomes available for the spacecraft, details of the 1+ hr time periods within the broad interval December 1996 through March 1997 will be posted together with other scheduling information.

A number of preliminary planning meetings have already been held for the IAS. Two more are planned in the near future at the ICS3 and COSPAR (and, possibly, Spring AGU) meetings. Details of the meeting times etc., will be e-mailed to all participants and will be posted on the IAS WWW pages.

Michael Teague
Goddard Space Flight Center
Code 630
Greenbelt, Md. 20771
teague@nssdca.gsfc.nasa.gov

Cindy Cattell
University of Minnesota
Tate Laboratory of Physics,
School of Physics and Astronomy,
116 Church Street SE
Minneapolis, MN 55455-0112
cattell@belka.spa.umn.edu


The 210 degree Magnetic Meridian Observation Project and GGS

Michael Teague, Kazuo Shiokawa, Kiyohumi Yumoto

Imaging the Earth's magnetosphere by using ground-based magnetometer arrays is still one of the major techniques for investigating the dynamical features of solar wind-magnetosphere interactions. Such arrays make it possible (1) to study the magnetospheric processes by distinguishing between temporal changes and spatial variations, (2) to clarify the global latitudinal structures and propagation characteristics of magnetic variations from high to equatorial latitudes along the magnetic meridian (MM), and (3) to understand the global generation mechanisms for magnetospheric phenomena. During the international Solar Terrestrial Energy Program (STEP) period of 1990-1997, the Solar -Terrestrial Environment Laboratory (STELAB), Nagoya University, is conducting multinationally coordinated magnetic observations along the 190 deg, 210 deg, and 250 deg MMs from high latitudes through middle and low latitudes to the equatorial region and spanning L from 8.5 to 1.0. The program involves cooperation between 29 organizations in Australia, Indonesia, Japan, Papua New Guinea, the Philippines, Russia, Taiwan, and the United States and is lead by K. Yumoto of Nagoy University (K.Yumoto will move to Kyushu University on February 1, 1996). Details of the organizations and Principal Investigators involved may be obtained from K. Yumoto, Y.Tanaka,T.Oguti, K.Shiokawa, Y.Yoshimura, A.Isono,B.J.Fraser, F.W.Menk, J.W.Lynn, M.Seto and the 210 MM Magnetic Observation Group.

Globally Coordinated magnetic observations along the 210 (deg) magnetic meridian during the STEP period:1. Preliminary results of low-latitude Pc 3's, J. Geomag. Geoelectr., 44, 261-276, 1992.

M_MERIDIAN_icon
Map showing the locations of the 190 deg, 210 deg, 250 deg MM chain stations in geographic coordinates

The MM project presently includes 35 stations; 11 associated with the 190 deg MM, 20 with 210 deg and 4 with 250 deg. The total network is summarized in the above figure. Details of the station locations, corrected geomagnetic coordinates and L-Values can be obtained from the STELAB WWW pages (URL: http://stelab2.stelab.nagoya-u.ac.jp/ ) (Click "STEP Database Catalogue" and then, "210 Magnetic Data - Magnetic home page") and from the Ground-Based WWW pages developed at GSFC/Code 630 (URL: http://iacg.gsfc.nasa.gov/iacg/ground_stations/ground_stations.html .). The former WWW pages include details concerning data availability and the latter pages include information on a wide variety of Ground-Based networks and projects.

Magnetometers are included at all of the sites shown in the figure. In addition, all-sky television cameras and photometers are installed at the following sites: MSR (Moshiri), TIK (Tixie), ZGN (Zhigansk), and KOT (Kotzebue). Routine magnetic observations by the 190 deg, 210 deg, and 250 deg MM chain will continue during the entire STEP period of 1990-1997. The magnetic data are being compiled at the Solar-Terrestrial Environment Laboratory. One-minute averaged magnetic data for 1990-1995 are available for file transfer through anonymous-ftp site at the Solar-Terrestrial Environment Laboratory (IP address = 133.47.128.10), and 1-minute summary plots for the 210 deg chain are available from the STELABWWW pages given above. Requests for data from these sources should be directed to K. Shiokawa at the below address. Users of these data are requested to contact K. Yumoto (Principal Investigator) before using these data at any presentation or publication.

Although the above data are normally made available to STEP investigators only, the 210 MM deg team has agreed to provide the 1-min data set to the ISTP/GGS community for inclusion in, and distribution from, the CDHF Key Parameter database. These data are presently in process of being converted to the CDF standard by GSFC Code 630 and will be available through the CDHF in the near future. The high-time resolution 1-sec data can ordinarily be used only for collaborative studies with the 210 deg MM team and requestors of these data should contact K. Yumoto at the address given below. However, the 210 deg MM team has agreed to make the 1-sec data available for the Magnetopause Skimming Campaign intervals (Dec.17,18,and 27,1994) and these data are also in process of being converted to the CDF standard by GSFC Code 630. Upon completion, these data will be included in the campaign WWW pages (URL: http://bolero.gsfc.nasa.gov/~solart/overview.html ).

Users of these data are again requested to contact with K. Yumoto (Principal Investigator) before using these data at any presentation or publication. Note, the time tags of the 1-sec files are not corrected by the standard time. The error in the time tag may be several tens of seconds. Users should contact K. Shiokawa concerning the data quality.

Michael Teague
Goddard Space Flight Center
Code 630
Greenbelt, Md. 20771
teague@nssdca.gsfc.nasa.gov

Kiyohumi Yumoto
Kyushu University
Dept. of Earth & Planetary Sciences
6-10-1, Hakozaki, Higashi-ku
Fukuoka 812, Japan.
yumoto@geo.kyushu-u.ac.jp

Kazuo Shiokawa
Nagoya University, STELAB, 3-13 Honohara
Toyokawa, Japan
shiokawa@stelab.nagoya-u.ac.jp


The Heliospheric Current Sheet: Comparisons of a Solar Surface Model with Observations at 1 AU from WIND Magnetic Field Data at Solar Minimum

R. P. Lepping, A. Szabo, M. Peredo, and J. T. Hoeksema

The following brief article is part of a letter to appear in the Geophysical Research Letters in the near future also authored by those listed above.

An extensive amount of WIND magnetic field data have been analyzed in detail around regions when the Heliospheric Current Sheet (HCS) passed by the spacecraft. The overall analysis period was essentially from launch in early November 1994 to Day 93 of 1995. Two of the purposes of the study were to gain a more comprehensive understanding of the properties of the HCS and to compare it to a well known solar source surface model [Hoeksema, 1989] of this current sheet as it is envisioned to be 'projected' from the sun to 1 AU, and especially to compare its timing at the two locations. This article will concentrate only on this comparison of the relative timing and on any evolutionary characteristics. The HCS is well known to separate the interplanetary magnetic field sectors, and therefore is another name for a sector boundary, which was the former terminology used for the HCS at 1 AU.

The definition of an individual HCS crossing used in this work was a magnetic field transition through about 180 degrees in no more than 10's of minutes from one relatively stable sector-state polarity to the other, allowing for the fact that the field in either sector is often not aligned with the average field direction, but tends to be so on the longterm. The nearly 180 degree direction change across the discontinuity could be partly contributed to latitude change in the field, but typically it was mainly due to a longitude change.

SZABO_icon

Figure 1 - Showing the observed distribution of sectors during the observation period, which occurs near solar minimum

Figure 1 shows the observed distribution of sectors during the observation period, which occurs near solar minimum. The data is presented in 27-day panels to allow easy identification of solar rotation periodicities. The lowest and thickest strip, within these panels, indicates the IMF polarity measured by WIND. A dark blue strip indicates negative polarity, whereas a white strip indicates positive polarity. The light blue intervals are the regions where the multiple individual HCS crossings were identified via a field variance analysis. On average there is a noticeable vertical alignment of the strips indicating a periodicity at the solar rotation period. Notice that during this period, there is a smooth changeover from a 2 sector structure (1 + and 1 - sector) to a four sector structure (2 + and 2 - sectors). The width of the negative sector in the middle of each 27-day time strip is slowly growing with time until the end of our observation period, where the 4 sectors have nearly the same length. In terms of the solar source, the four-sector pattern developed as the nearly flat but inclined neutral line formed a new warp that crossed the ecliptic plane. This resulted in a progressive change from a pair of 180 degree sectors to a set of four caused by the 90 degree warps of the neutral line. Hence, in the frame of reference of WIND, for the particular speeds of the solar wind observed, the 'four sector' structure in 3-D corresponds to a 1 - 2 AU wave at 1 AU, which is a particular example of a 'ballerina skirt' current sheet.

Next we attempted to correlate this large scale evolution of the HCS to the timing of magnetic field variations on the surface of the Sun as determined by two models.

We started with the source surface map of the coronal field by Hoeksema [1989] and determined the times when the Earth-Sun line crossed the solar magnetic equator. Using the radial solar wind velocity measurements at WIND propagated back to the surface of the Sun properly taking into account the rotation of the Sun (although ignoring all possible interactions between adjacent fluid parcels which lead to a significant uncertainty in our mapping). Then we determined the times when solar wind plasma observed at WIND could have originated from the solar equatorial regions. In our modeling we employed two versions: (1) the "classic" (CSF) coronal potential field source surface model, which uses the "line-of-sight" inner boundary condition and a polar field correction at a source surface at 2.5 Rs (where Rs is the radius of the Sun) and (2) a "radial" (RSF) inner boundary condition model, which has no polar field correction and has a source surface radius of 3.25 Rs. Figure 1 also shows the results of the correlation of the source surface models with the WIND observations. The darker colored lines (marked by either green for CSF or orange for RSF) correspond to times when we believe that the solar wind had originated from the negative polarity region of the Sun, whereas the white panel indicates positive polarity source areas. Also, to give some indication of the broadness of the transition from one polarity to the next, we have marked by yellow segments the periods when the Earth-Sun line was within a certain small angle of the solar magnetic neutral line: 0.1 degree for the RSF model and 1.0 degree for the CSF model. The RSF model is much flatter and, hence, the Earth-Sun line stays much closer to the computed heliomagnetic equator. To achieve good correlations between the solar predictions and indications of sectors from WIND data, we had to offset the solar wind propagation time by one extra day, which was estimated qualitatively. Part of this offset is likely to be due to the solar wind acceleration known to occur between the source surface and about 20 Rs, and partly to our ignoring effects of stream interactions. Also there is an about +/- 1 day uncertainty in our propagation time determination. Nevertheless, the correlation is remarkable, clearly showing the close relationship between the evolution of the solar magnetic fields and the HCS.

Ref.: Hoeksema, J. T., Adv. Space Res., 9, (4)141-(4)152, 1989.

R. P. Lepping
Goddard Space Flight Center
Code 696
Greenbelt, Md. 20771
(301) 286-5413
rpl@leprpl1.gsfc.nasa.gov

A. Szabo
Goddard Space Flight Center
Code 696.0
Greenbelt, Md. 20771
(301) 286-5726
asz@leprpl1.gsfc.nasa.gov

M. Peredo
Raytheon STX
Goddard Space Flight Center
Mail Stop 632.0
Goddard Space Flight Center
Greenbelt, Md. 20771
(301) 286-1526
peredo@istp1.gsfc.nasa.gov

J. T. Hoeksema
Center for Space Science and Astrophysics
ERL 328
Stanford University
Stanford, Ca. 94305
(415) 723-1506
todd@quake.stanford.edu


IACG First Campaign Update and the SM05 Session at the Spring AGU

J. Green, M. Peredo, and M. Teague

As discussed in the last issue of this newsletter, the first phase of the 1st IACG campaign on the dynamics of the magnetotail has completed the data acquisition phase and is now passing into the data collection and analysis phases. Eleven intervals, from October 1995 to January 1996, were selected from predictive orbit data using the criteria that the Geotail spacecraft and the Interball Tail probe were in the magnetotail while the Wind spacecraft was monitoring the interplanetary medium. For reference, the eleven intervals are:

October 18 - 21, 1995 (Day 291-294)
October 26 - 27, 1995 (Day 299-300)
October 31 - November 1, 1995 (Day 304-305)
November 11 - 12, 1995 (Day 315-316)
November 17, 1995 (Day 321)
November 28 - 29, 1995 (Day 332-333)
December 3 -4, 1995 (Day 337-338)
December 7, 1995 (Day 341)
December 15, 1995 (Day 349)
December 18 - 20, 1995 (352 - 354)
January 12, 1996 (Day 12)

Key Parameter data from all eleven intervals are now available from the CDHF and the NSSDC. Based upon a review of these key parameters by the authors, D. Fairfield, and others at GSFC Code 630, four of these intervals have been provisionally identified as showing particularly interesting variations in the key parameter data. They are: Days 291-294 (The "Cloud" event), Days 304-305, Day 332-333 and Day 349. (Note that no key parameter data were available from the eleventh interval at the time this review was conducted).

A key mechanism for the dissemination of information and data on the IACG and other ISTP-related campaigns is the WWW. The IACG homepage URL is http://iacg.org and the specific homepage for the 1st campaign is http://iacg.org/iacg/campaign_1.html . Information on other ISTP-related correlative studies is accessible from the SPDF homepage at URL http://nssdc.gsfc.nasa.gov/space/spdf/spdf.html . In addition to campaign information, rules of the road, and custom summary plots of Key Parameter data, these web pages provide access to the CDAWeb system which allows interactive plotting of key parameter data. In the future we anticipate that higher time-resolution science data will be included in these home pages and these data, also, will be accessible by the CDAWeb system.

The authors, together with A. Pedersen, D. Baker, N. Maynard, and T. Sanderson are conveners for a special Spring AGU Session (SM05) entitled "Initial Results from Coordinated Solar-Terrestrial Data Analysis Campaigns". These special session will include approximately 20 invited poster papers which will present initial results from a number of campaigns including the IACG Tail campaign intervals listed above, the Wind-Geotail Magnetopause Skimming Campaign intervals and several GEM campaign intervals based upon the Wind and Geotail spacecraft. Included in these invited papers will be a review of all the Tail campaign intervals using the Key Parameter data. A feature of the special session, is that many of the invited papers (and possibly some of the contributed papers) will be supported by computer access to the WWW which will allow the authors interactive access to a variety of databases.

Please direct questions and comments on these campaigns to the authors at green@nssdca.gsfc.nasa.gov , peredo@istp1.gsfc.nasa.gov and teague@nssdca.gsfc.nasa.gov . In particular, we are interested in suggestions concerning the specific datasets which we may acquire for inclusion in the Tail campaign and Skimming campaign WWW pages.

J. Green
Goddard Space Flight Center
Mailstop 630.0
Greenbelt, Md. 20771
green@nssdca.gsfc.nasa.gov

M. Peredo
Raytheon STX
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
peredo@istp1.gsfc.nasa.gov

Michael Teague
Goddard Space Flight Center
Code 630
Greenbelt, Md. 20771
teague@nssdca.gsfc.nasa.gov


Space Physics Catalog (SPyCAT) Access to NSSDC/SPDF Nearline Data

E. Greene, K. Horrocks, R. Candey, R. Kessel, R. McGuire, and J. King

The NASA/GSFC National Space Science Data Center (NSSDC) and Space Physics Data Facility (SPDF) are pleased to announce a NEW WWW-based interface to facilitate electronic retrieval of a wide range of NSSDC-held space physics data including the newly-released International Solar Terrestrial Physics (ISTP) program Key Parameters (KPs). This new interface, termed the Space Physics Catalog or SPyCAT, supports access to data held "nearline" in the NASA/NSSDC Data Archive and Distribution System (NDADS) from space physics missions that now include:

The SPyCAT interface may be found at the WWW URL: http://nssdc.gsfc.nasa.gov/space/ndads/spycat.html

The SPyCAT interface operates in several steps from an initial user specification of the mission, dataset and a range of times of interest to a detailed inventory of the specific data files available from NDADS to the user's request to NDADS for data. As a nearline system, NDADS then processes data requests in a "batch" mode to stage requested files to an anonymous FTP area. At the user's discretion and with appropriate account information, NDADS can also place the data on the user's machine. NDADS sends e-mail notification when files have been staged. All data may also be requested from NDADS via its Automated Retrieval by [Electronic] Mail System (ARMS).

While SPyCAT and the underlying NDADS system are fully operational, a series of hardware and software upgrades are in progress to improve system response times. During this period, users may find variable response times depending on the system and network load.

Questions and comments about the SPyCAT interface may be directed to Dr. Emily Greene (301-441 -4234, emily@ncf.gsfc.nasa.gov ) or through Dr. R. McGuire (301-286- 7794) mcguire@ncf.gsfc.nasa.gov ). Questions about space physics data, NDADS and other services of NSSDC may be directed to any of the authors above or to the NSSDC Coordinated Request and User Support Office (CRUSO, 301-286-6695, request@ncf.gsfc.nasa.gov , FAX: 301-286-1771).

E. Greene
NASA
Goddard Space Flight Center
Mailstop 632.0
Greenbelt, MD 20771
emily@xfiles.gsfc.nasa.gov

K. Horrocks
NASA
Goddard Space Flight Center
Mailstop 632.0
Greenbelt, MD 20771

R. Kessel
NASA
Goddard Space Flight Center
Mailstop 632.0
Greenbelt, MD 20771
kessel@nssdca.gsfc.nasa.gov

R. McGuire
NASA
Goddard Space Flight Center
Mailstop 632.0
Greenbelt, MD 20771
mcguire@ncf.gsfc.nasa.gov

J King
Goddard Space Flight Center
Mailstop 633.0
Greenbelt, MD 20771
king@nssdca.gsfc.nasa.gov

R. Candey
NASA
Goddard Space Flight Center
Code 632.0
Greenbelt, Md. 20771
candey@nssdca.gsfc.nasa.gov


A new-generation global magnetosphere field model, based on spacecraft magnetometer data.

N.A. Tsyganenko and D.P. Stern

model_icon

A 3-D view of the model field lines with footpoints in the noon-midnight meridian plane.

Considerable progress was recently achieved in the development of magnetospheric models based on large sets of spacecraft magnetometer data. Such models are widely used for the interpretation of ground-based and spacecraft data by mapping lines of force, tracing orbits of particles and modeling magnetospheric convection, and they are thus crucially important for achieving the goals of ISTP.

This article describes the latest release of an advanced data-based model, founded on new principles [Tsyganenko, 1995]. It incorporates all principal sources of the magnetic field, including the large -scale system of field aligned currents, and it allows a partial penetration of the solar wind field into the magnetosphere, creating an "open" configuration. The model is based on measurements of the magnetic field over a wide range of geocentric distances, between 4 and 70 Earth radii, made by the various IMP, HEOS and ISEE spacecraft during 1966-1986 and combined into a single large database, containing about 80,000 data records and described in detail by Fairfield et al. [1994].

Unlike earlier models in this series, this one assumes the shape of the magnetopause to be explicitely given, by a model based on observed magnetopause crossings [Sibeck et al., 1991]. The size of the modeled magnetopause is controlled by current values of the solar wind dynamical pressure, so that it decreases and increases in response to increasing or decreasing density and velocity of the solar wind particles.

The model includes realistic ring and tail currents [Tsyganenko and Peredo, 1994], mathematically described by separate simple and flexible modules whose parameters depend continuously on the solar wind pressure Pdyn , on the interplanetary magnetic field (IMF), and for the ring current, on the Dst index. The coefficients which give the geometrical characteristics of these current systems and their dependence on external factors were fitted by least squares to the entire body of spacecraft magnetometer data, using a new "directional" criterion which gave a more accurate characterization of magnetic field lines than did earlier versions.

A special feature of the new model, absent from all earlier empirical representations of the distant field, is the contribution of large-scale systems of Birkeland currents [Iijima and Potemra, 1976a, b], flowing along geomagnetic field lines at low altitudes and connecting either to the magnetosheath (Region 1) or closing through an equatorial partial ring current on the night side (Region 2). The model's Birkeland currents depend on the solar wind parameters (Region 1) and on the AE index (Region 2).

Their inclusion had a significant effect on the configuration of the dayside magnetosphere: as the interplanetary magnetic field intensifies and turns southward, the magnitude of the Region 1 current was found to rapidly increase, resulting in a transfer of magnetic flux from the day side to the night side and a dramatic equatorward shift of the polar cusps.

Allowing a partial penetration of the interplanetary magnetic field leads to a non-zero normal component Bn of the magnetic field on the magnetopause, which depends on the strength and on the direction of the IMF. The amount of magnetic flux penetrating the magnetosphere from the outside has been correlated with the observed transverse components By and Bz of the IMF, and the value of the variable factor controlling that penetration was again found by least squares fitting to the whole set of space magnetometer data.

The input parameters of the model are thus (1) the solar wind dynamic pressure Pdyn (2) The AE and Dst indices of geomagnetic activity (3) the transverse components By and Bz of the IMF and (4) the geodipole tilt angle Y. Figure 1 displays the modeled configuration of magnetic field lines in the Earth's magnetosphere for a typical combination of these parameters.

The model has been implemented by a set of FORTRAN-77 subroutines and is available on request by E-mail ( ys2nt@lepvax.gsfc.nasa.gov ) from one of us (N.A.T.). For additional information on magnetic field models developed and distributed by the GSFC Magnetospheric Modeling Group, please see the modeling homepage at URL http://pwg.gsfc.nasa.gov/Modeling/group.html

References

Fairfield, D.H., N.A. Tsyganenko, A.V. Usmanov, and M.V. Malkov, A large magnetosphere magnetic field database, J.Geophys.Res., 99, 11319-11326, 1994.

Iijima, T, and T.A. Potemra, The amplitude distribution of field- aligned currents at northern high latitudes observed by Triad, J.Geophys.Res., 81, 2165-2174, 1976a.

Iijima, T, and T.A. Potemra, Field-aligned currents in the dayside cusp observed by Triad, J.Geophys.Res., 81, 5971-5979, 1976b.

Sibeck, D.G., R.E. Lopez, and E.C. Roelof, Solar wind control of the magnetopause shape, location, and motion, J.Geophys.Res., 96, 5489-5495, 1991.

Tsyganenko, N.A. and M. Peredo, Analytical models of the magnetic field of disk-shaped current sheets, J.Geophys.Res., 99, 199-205, 1994.

Tsyganenko, N.A., Modeling the Earth's magnetospheric magnetic field confined within a realistic magnetopause, J.Geophys.Res., 100, 5599-5612, 1995.

David P. Stern
NASA
Goddard Space Flight Center
Greenbelt, Md. 20771
u5dps@lepvax.gsfc.nasa.gov

N.A. Tsyganenko
Hugues STX
Goddard Space Flight Center
Mailstop 695.0
Greenbelt, Md. 20711
ys2nd@lepvax.gsfc.nasa.gov


Public Release of ISTP Key Parameter Data

R. Kessel, M. Peredo, R. McGuire, and J. King

The National Space Science Data Center (NSSDC) has received authorization from the NASA Global Geospace Science (GGS) and International Solar-Terrestrial Physics (ISTP) program to begin public distribution of ISTP Key Parameter data from NASA-funded and ancillary investigations.

These data include approximately 1 minute resolution observations from: (1) all instruments on WIND, (2) the Comprehensive Plasma Instrument (CPI) and Energetic Particle and Ion Composition (EPIC) investigations on GEOTAIL, (3) the magnetic field (MAG) and MIT plasma (PLA) instruments on IMP-8, (4) the DARN and SONDRESTROM ground-based investigations [except PACE], and (5) geosynchronous investigations from the GOES 6/7 (MAG and EPS instruments) and LANL 1989/1990/1991 (SOPA and MPA instruments) spacecraft. By previous arrangement, ISTP and NSSDC (working jointly with the NASA/GSFC Space Physics Data Facility/SPDF), transfer the ISTP Key Parameters (KPs) into the "nearline" NASA/NSSDC Data Archive and Distribution System (NDADS) in as little as 3-5 days of the time of the original measurements.

Potential data users must note that ISTP KPs are preliminary products intended to be used for browse purposes ONLY. Users interested in presentation or publication quality data are encouraged to contact the appropriate Principal Investigator(s).

The SPDF and NSSDC are also pleased to announce a new WWW-based interface to facilitate retrieval of a wide range of space physics data held in NDADS that includes these ISTP KPs and a wide variety of space physics data (including other IMP-8 data products). For details on access and use of this new interface (termed SPyCAT), please see the accompanying article in this newsletter.

Questions and comments to the availability, access and appropriate use of these data may be addressed to ISTP and NSSDC/SPDF through:

Dr. R. Kessel (301-286-6595, kessel@ncf.gsfc.nasa.gov ), Dr. R. McGuire (301-286-7794, mcguire@ncf.gsfc.nasa.gov ) or to the NSSDC Coordinated Request and User Support Office (CRUSO, 301-286-6695, request@ncf.gsfc.nasa.gov , FAX: 301-286-1771).

R. Kessel
NASA
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
kessel@ncf.gsfc.nasa.gov

R. McGuire
NASA
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
mcguire@ncf.gsfc.nasa.gov


SOHO Joins ISTP Missions

M. A. Calabrese

The third of five prime missions in the International Solar Terrestrial Physics (ISTP) ensemble was added on December 2, 1995 when the ESA/NASA Solar and Heliospheric Observatory (SOHO) was launched into orbit by an Atlas IIAS launch vehicle from Cape Canaveral Air Force Station, Florida.

SOHO was initially placed into a transfer orbit en route to its destination at the Lagrangian-1 ) (L1) point about one million miles from the Earth in the direction of the Sun where the gravitational pull between the Earth and the Sun is equal. The initial commissioning was successfully conducted on the spacecraft and the scientific instruments during this period. The scientific instruments saw first light in January, 1996 after an outgassing period. The accuracy of the transfer orbit placement followed by small midcourse corrections and an early L-1 halo orbit insertion on February 14, 1996, has preserved fuel and gives the prospect for SOHO to enjoy many years of scientific operations.

The international science team operate their instruments from the SOHO Experiment Operations Facility at GSFC. Dr. Roger Bonnet/ESA and Dr. Wesley Huntress, Jr./NASA recently visited the principal investigators at the GSFC SOHO Experiment Operations Facility to see the initial results and congratulate the team. The first science results press briefing is planned for May 2, 1996. Initial SOHO science data indications are that solar physics textbooks will be rewritten much as they were after the Skylab Apollo Telescope Mount mission.

SOHO will investigate the flow of energy from the solar interior to the corona where the solar wind is generated. SOHO will complement Geotail (7/24/92), Wind (11/1/94), and Polar (2/23/96) in support of the ISTP Science Initiative. The ESA/NASA Cluster (5/96) mission is planned to complete the prime mission implementation of the ISTP ensemble in 1996 supported by theoretical and ground based investigations. Complementary equatorial data is being provided to ISTP science by the GOES and LANL satellites and will be supplemented by the DARA/NASA Equator-S mission planned for launch 2/97. Current mission status is available on the SOHO Internet Home Page ( http://SOHOWWW.NASCOM.NASA.GOV).

M. A. Calabrese
SOHO Program Manager
NASA Headquarters
Washington, D. C. 20456


New Location for the ISTP/SPOF Web server

M. Peredo

In order to meet the anticipated increase in activities on the SPOF web server after Polar launch, the SPOF server has undergone some redesign, and has moved to a more powerful platform. The new URL is http://pwg.gsfc.nasa.gov/ . From the top level homepage, users can find access to:

  1. science planning information (including spacecraft trajectory plots, long term science plan reports, and the upcoming Polar science operations plan),
  2. key parameter summary plots (custom daily plots exist for Wind, Geotail, IMP-8 and Geosynchronous and ground-based data; 27-day plots are available for Wind data, additional custom plots will be created once Polar key parameters are available),
  3. information on ISTP and IACG science campaigns and events (links to existing campaign pages as well as access to the current catalog of solar wind events and the future ISTP/GGS science event catalog),
  4. educational and outreach products (including The Exploration of the Magnetosphere), and
  5. pointers to other web sites with ISTP-related information.

As always, comments and suggestions from the ISTP and space physics community are welcome. Please address them to:

M Peredo
(Raytheon STX Corporation ISTP/SPOF)
Goddard Space Flight Center
Greenbelt, Md. 20771
(301) 286-1526
peredo@istp1.gsfc.nasa.gov


Satellite Situation Center Releases V. 2.2 of SSC Software

R. McGuire, T. Kovalick, R. Parthasarathy and M. Peredo

The Satellite Situation Center has been developed and is operated jointly by the NASA/GSFC Space Physics Data Facility (SPDF) and the National Space Science Data Center (NSSDC) to support a range of NASA science programs and to fulfill key international NASA responsibilities including those of NSSDC and the World Data Center-A for Rockets and Satellites.

The software and associated database of the Satellite Situation Center (SSC) form together a system to cast spacecraft location information into a framework of (empirical) geophysical regions and mappings of spacecraft locations along lines of the Earth's magnetic field. This capability is one key to mission science planning (both single missions and coordinated observations of multiple spacecraft with ground-based investigations) and to subsequent multi-mission data analysis. This system directly supports the operational SSC and ISTP's Science Planning and Operations Facility (SPOF).

The SPDF and NSSDC are pleased to make the newest version (2.2) of the SSC system directly available for interactive use by NASA and other interested science users. The new version 2.2 includes extensive updates to the magnetic field models and geospace region definitions employed, and will be the official version used by the SPOF for ISTP science planning and coordination activities.

Access to the SSC system is supported for both VT/character and X-windows users via telnet. For additional information on how to access the system, or models employed, please access the SSC homepage on the world wide web at URL http://sscop1.gsfc.nasa.gov/ssc.html .

Please address comments or questions to:

M. Peredo
Raytheon STX
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
(301) 286-1526
peredo@istp1.gsfc.nasa.gov

R. McGuire
NASA
Goddard Space Flight Center
Mail Stop 632.0
Greenbelt, Md. 20771
(301) 286-7794
mcguire@nssdca.gsfc.nasa.gov


Near-Real-Time Server, an Enhancement to the Central Data Handling Facility (CDHF) Near-Real-Time (NRT) Subsystem

Dick Schneider

Overview

The ISTP CDHF has recently implemented an enhancement to the NRT subsystem that provides for the continuous and simultaneous transfer of Wind and Polar NRT level-zero (LZ) packet data frames from the CDHF to remote user sites. This new capability supports the NRT data flow during single or simultaneous Wind and Polar spacecraft real-time passes for which science or maneuver mode data are received. The NRT data, acquired from the Deep Space Network (DSN), are forwarded directly to a dedicated set of CDHF processors bypassing the Generic Data Capture Facility (GDCF). At the CDHF, the downlinked data are edited and decommutated into instrument LZ and housekeeping (HK) major frames and are made available to users with a minimum of delay.

Since the new NRT enhancement is an added CDHF feature, the existing NRT LZ (non-continuous) file extraction capability is preserved as originally implemented.

Client/Server Environment

The NRT upgrade is implemented in a TCP/IP (no DECnet access is available) client/server environment. The NRT Server supports the NRT packetization of instrument major frames and the distribution of resulting LZ formatted data to user sites. NRT Client software is in turn employed by users to connect to the NRT Server and to request and receive major frames as they become available. The requested packetized data are sent to the Client from the Server over the NASA Science Internet (NSI) via a TCP socket connection, providing authorized clients with LZ data as it becomes available.

The format of the NRT LZ packets, which is described in the ISTP Data Format Control Document (DFCD), appears in the same major frame format as that of the LZ playback data and consists of a major frame header followed by minor frames of data.

User client software is developed using an NRT Client Support Library available on the CDHF. Four routines are required by the Client to connect, login, request, and receive data from the NRT Server.

The Client library is portable (written in C language) and has been run successfully under VAX/VMS 6.1, DEC Alpha/Open VMS 6.2, SUN Solaris 2.4, and Windows NT/Windows 95. The Client library may be obtained from the ISTP CDHF (istp1.gsfc.nasa.gov) via anonymous ftp as well as directly on the CDHF from the SYS$PUBLIC:[NRT] directory.

Utilization

Presently, over half a dozen Polar and one or two Wind users have developed NRT Clients and it is likely that additional users will be gained in the post-Polar launch time period. Past and present user intentions polls indicate that this added capability will be used during instrument turn-on and checkout and periodically over mission life for instrument health and safety checks, quick-look science data, and for other situations where time critical instrument to user response is required. In addition, a potential user has expressed intent to use the NRT capability in support of sounding rocket launches.

Restrictions

Access to NRT data from the NRT Server is governed by the same set of privileges that control access to the production (playback) LZ data files.

Depending on the impact on CDHF and NSI resources, the number of simultaneous NRT users from each investigation may have to be limited.

Getting Started

For more information on the NRT subsystem, contact Rusty Whitman (NRT development lead) at whitman@istp2.gsfc.nasa.gov (e-mail preferred) or 301-794-2361. Additional information can be obtained from the ISTP NRT WWW site at URL http://pwg.gsfc.nasa.gov/ISTP/NRT.html .

Dick Schneider
ISTP Project CDHF System Manager
Goddard Space Flight Center
Code 407
Greenbelt, Md. 20771
301-286-5543
schneider@istp1.gsfc.nasa.gov



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