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Publications (2)0 Total impact

  • A. Dmitriev, J. Chao, Y. Yang, D. Wu
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    ABSTRACT: The bow shock (BS) crossings by the Wind and Geotail are selected using ISTP data base in 1998 to 2001. We have analyzed 625 case events containing 4381 BS crossings by Geotail and 130 case events containing 917 BS crossings by Wind. The location of the BS crossings in aberrated GSE coordinate system varies in wide range from -85 Re to 45 Re along the X axis and up to 90 Re in perpendicular direction. The upstream solar wind conditions measured by ACE, Wind and Geotail in the interplanetary medium are determined for the BS crossings in each case event using time delay for direct solar wind propagation from an upstream monitor to a probe satellite (Wind or Geotail). The additional time lag is introduced to achieve the best correlation between time profiles of the solar wind plasma parameters and interplanetary magnetic field (IMF) measured by the upstream monitor and the probe satellite. Solar wind conditions for the BS crossings vary in wide ranges of solar wind dynamic pressure Pd (from 0.02 nPa to 49 nPa), IMF Bz (from -26 nT to 23 nT), thermal-magnetic pressure ratio (from 0.002 to 50), and magnetosonic Mach number (from 1.02 to 29). Such wide spatial and dynamic range of the BS crossings permits consideration of different parameters controlling the BS size and shape such as the radius of curvature of the magnetopause depending on Pd and Bz, the Alfvenic, sonic and magnetosonic Mach numbers, thermal-magnetic pressure ratio and IMF orientation. To study the dependence on these parameters we compare the accuracy of the BS models by Peredo et al. [1995], Russell and Petrinec [1996], Verigin et al. [2001], and Chao et al. [2002] in prediction of the selected BS crossings observed in different regions of the bow shock and under various ranges of the upstream solar wind conditions.
  • A. Dmitriev, J. Chao, Y. Yang, R. Lepping, D. Wu
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    ABSTRACT: High resolution data from Geotail, WIND and ACE satellites are used for selection 32 intervals of extreme bow shock location during years 1999-2000. In 16 intervals of very strong upstream solar wind conditions the bow shock subsolar distance r0 is less than 10 Earth radii (Re). In the other 16 intervals of tenuous solar wind the bow shock is located very far from the Earth and r0 is more than 20 Re. During considered intervals the bow shock crossings are observed in different regions from the dayside to far tail (40 Re in anti sun direction). Existing bow shock models predict the crossings with different accuracy depending on the upstream conditions and on the bow shock region. During strong disturbed conditions the prediction of the dayside and flank regions of the bow shock is pretty well but in the regions of close and far tail the bow shock distance is overestimated. The same situation with flaring of the tail bow shock is observed for tenuous solar wind. Prediction of the bow shock under very weak solar wind on the dayside is more complicated and bow shock distances may be both overestimated and underestimated in dependence on upstream solar wind conditions. The solar wind and model parameters responsible for these disagreements are discussed.