We present here some results of the near real time (once in 90 minutes) running of our 3D magnetosheath gasdynamic numerical model. The determination of the shape and position of the bow shock and the magnetopause is a part of the solution.
| The red lines | correspond to the parameter values, measured by ACE at the pointed time moment. (Note that "the same" solar wind reaches the earth about one hour later); |
| The green lines | correspond to a time moment, which is 90 minutes earlier; |
| The blue lines | are obtained three hours earlier that red ones. |
| The dashed line | presents for comparison the magnetopause, predicted by the semi empirical model of Shue et al., 1998, under the same (the latest) conditions. |
The axes are scaled in earth radiuses
One can understand the model approach from the 2D variant of the model, presented in the paper of Kartalev et al., 1996. The utilized here 3D variant was developed by V. Keremidarska and M.Kartalev. The Internet adaptation was helped by K.Grigorov and D.Romanov.
Besides the 3D generalization, an essentially new
point in the present approach is the usage of the realistic Tsyganenko
magnetosphere model T96_01 (http://www-spof.gsfc.nasa.gov/Modeling/group.html
, http://nssdc.gsfc.nasa.gov/space/cgm/t96.html)
for ensuring the pressure balance at the magnetopause. This version of Tsyganenko
model is parameterized by the IMF By and Bz components, solar wind dynamic pressure,
and the Dst index used as the input parameters. The needed geodipole tilt angle is
determined using the code of Tsyganenko and Peredo
( http://www-istp.gsfc.nasa.gov/Modeling/geopack.html
) .
Note: We switch off the option "built in magnetopause shape" in the code T96_01. Only the case "inside the magnetosphere" (case (1) there) is in use here. The magnetopause position is settled during the solution satisfying only the pressure balance condition.
In this realisation we use a real time ACE data (gopher://sec.noaa.gov:70/11/lists/ace/
), averaged over a 6 minutes time interval.
We acknowledge Paul O'Brien from UCLA for kindly providing the real time Dst
index (http://obrienpc.igpp.ucla.edu/unixwww/rt_dst/
). See also the papers of O'Brien and McPherron, 2000.
Note: The solar wind electron
temperature Te, essential in determining the Mach number, is not available yet
in the ACE Internet site. Currently we accept an estimate, based on the available in real
time proton temperature Tp :
Te = 3 Tp
Acknowledgments: This project was partially supported by Bulgarian Science Foundation (Grants NZ 522 and MU I 0598)
References:
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