An observational test of the Tsyganenko (T89a) model of the magnetospheric field

The range of magnetic field tilt angles observed at several satellites in geosynchronous orbit is compared with the ranges predicted for the same locations by the different Kp parameterizations of the Tsyganenko 1989a magnetic field model as a function of local time and season. The data are examined separately for satellite locations near the magnetic equator and slightly off the equator. The model predicts reasonably well the observed basic variation in the tilt angle with location, and it permits a range of field inclinations adequate to encompass the majority of the observed angles for the dawn, dusk, and night quadrants. On the day side of the magnetosphere the model exhibits very little variation in tilt over the entire range of parameterizations and cannot reproduce the observed range of tilt angles. Near the magnetic equator the majority of observed tilt angles lie within the model range, with roughly equal numbers of cases that are overstretched or understretched with respect to the model range. Off the equator the models tend to be more stretched than is generally observed. With some modest season-to-season differences these results are valid for all four seasons.

[1]  R. Hilmer,et al.  A magnetospheric magnetic field model with flexible current systems driven by independent physical parameters , 1995 .

[2]  C. Lin,et al.  Magnetic field inclination angle at geosynchronous orbit , 1984 .

[3]  D. Stern,et al.  Empirical modeling of the quiet time nightside magnetosphere , 1993 .

[4]  Nikolai A. Tsyganenko,et al.  Determination of the magnetospheric current system parameters and development of experimental geomagnetic field models based on data from IMP and HEOS satellites , 1982 .

[5]  C. Huang,et al.  Magnitude of BZ in the neutral sheet of the magnetotail , 1994 .

[6]  M. F. Thomsen,et al.  Magnetospheric plasma analyzer for spacecraft with constrained resources , 1993 .

[7]  Ramon Lopez,et al.  Modeling the growth phase of a substorm using the Tsyganenko Model and multi-spacecraft observations: CDAW-9 , 1991 .

[8]  M. Sugiura,et al.  A method of evaluating quantitative magnetospheric field models by an angular parameter alpha , 1979 .

[9]  W. P. Olson,et al.  A quantitative model of the magnetospheric magnetic field , 1974 .

[10]  D. Stern,et al.  Are existing magnetospheric models excessively stretched , 1993 .

[11]  D. Stern,et al.  On the position of the near-earth neutral sheet - A comparison of magnetic model predictions with empirical formulas , 1991 .

[12]  D. Fairfield.  An evaluation of the Tsyganenko Magnetic Field Model , 1991 .

[13]  C. Russell,et al.  A test of the Hall-MHD Model: Application to low-frequency upstream waves at Venus , 1994 .

[14]  D. Weimer,et al.  The relationship between ionospheric convection and magnetic activity , 1994 .

[15]  Nikolai A. Tsyganenko,et al.  GLOBAL QUANTITATIVE MODELS OF THE GEOMAGNETIC-FIELD IN THE CISLUNAR MAGNETOSPHERE FOR DIFFERENT DISTURBANCE LEVELS , 1987 .

[16]  N. Tsyganenko.  A magnetospheric magnetic field model with a warped tail current sheet , 1989 .

[17]  D. Baker,et al.  Thin current sheets in the magnetotail during substorms: CDAW 6 revisited , 1994 .

[18]  D. H. Fairfield,et al.  A quantitative magnetospheric model derived from spacecraft magnetometer data , 1975 .

[19]  C. Russell,et al.  On the sources of interplanetary shocks at 0.72 AU , 1994 .

[20]  Nikolai A. Tsyganenko,et al.  A large magnetosphere magnetic field database , 1994 .

[21]  D. Stern.  The art of mapping the magnetosphere , 1994 .

[22]  B. Barraclough,et al.  Magnetospheric plasma analyzer: Initial three‐spacecraft observations from geosynchronous orbit , 1993 .

[23]  J. Phillips,et al.  Anisotropic thermal electron distributions in the solar wind , 1989 .