[logo] Collaborative Study of Earth's Bow Shock

Figure courtesy of "Tsurutani and Rodriguez, J. Geophys. Res., 86, 4319, 1981, copyright 1981 by the American Geophysical Union."

Earth's bow shock represents the outermost boundary between that region of geospace which is influenced by Earth's magnetic field and the undisturbed interplanetary medium streaming from the Sun. This boundary is important because it is here that the streaming solar wind is slowed, heated, and partially deflected around the Earth's magnetosphere. From solar wind observations, we know there exist rotational and tangential discontinuities, current sheets, magnetic holes and clouds , many of which eventually impact the Earth's magnetosphere with first contact at the bow shock. There are also any number of small scale structures, inhomogeneities, or perturbations present in the solar wind which hit the bow shock. As solar wind structures or changes in the solar wind impinge on the bow shock, it moves in response.

We have put together a database of Geotail bow shock crossings during 1995, 1996 and 1997. 1995 is the year in which Geotail switched from its deep tail mission to come in to an approximately 30 Re orbit ripe for studying magnetospheric boundaries. These years include the end of the descending phase, solar minimum and the start of the ascending phase of the solar cycle. We have concentrated on the crossings at the bow shock flanks because it is here that more motion and wave activity is expected - the nose is more tightly locked into place while the flanks can flap in the breeze.

In addition J. Safrankova and Z. Nemecek supplied two years worth - 1995, 1996 - of Magion-4 (Interball-Tail's sub satellite) bow shock crossings (approximately 1100 crossings). This orbit is highly elliptical and significantly out of the ecliptic plane.

Geotail and Magion-4 Bow Shock Crossings

For questions on Geotail Crossings contact Dr. Mona Kessel (mona.kessel@gsfc.nasa.gov)

For questions on Magion-4 Crossings contact Dr. Jana Safrankova (safr@aurora.troja.mff.cuni.cz)


Web access to the database was set up to facilitate statistical studies and cross-comparisons of the Earth's bow shock. This database stores a list of bow shock crossings as well as information associated with each crossing - solar wind parameters such as Magnetosonic Mach number, plasma beta, IMF Bx, By, Bz, model theta _Bn, and ram pressure

View the Bow Shock Crossings Database

The database design allows plots to be created for specific subsets of the database, the conditions specifying the subset supplied through the WWW-based interface. Current supported plots include:

Bow Shock Crossing Location Plots


Bow Shock Surface Orientation Plots



CDAWeb Interactive Plotting of all public ISTP Key Parameter data. These data are intended for browse purposes and particularly for identification of events, although some of this data is now "citable with caution". Users are encouraged to contact the appropriate Principal Investigator(s) if interested in using the data.

GIFWalk ISTP Science Planning and Operations Facility (SPOF) Orbit and Key Parameter Survey Plots

FTP directory of Orbit Plots provided through the Satellite Situation Center. Gif images can be viewed. Both Gif and PS images can be downloaded. Plots include (1) 4 day orbits from Wind, Geotail, Imp-8, Interball-Tail and the Moon on two length scales, (2) Polar orbits, and (3) 5 month long orbits from Wind.

FTP directory of Summary KP Plots provided by the ISTP Science Planning and Operations Facility. Plots are in GIF format and include selected variables from (1) combined daily geosynchronous and ground-based data, (2) Geotail daily data, (3) Wind daily data, (4) 27 day Wind data, and (5) monthly Wind data.


List of Presentations and Publications


Author and Curator

Mona Kessel, mona.kessel@gsfc.nasa.gov, (301)286-6595
Code 632, NASA Goddard Space Flight Center
Greenbelt, MD 20771, USA

NASA Official: R.E. McGuire, Head, Space Physics Data Facility
(Code 632, NASA/GSFC), Robert.E.McGuire@gsfc.nasa.gov, (301)286-7794
Last Updated: 17 Dec 1996, KCH