2008, 28(3): 203-209.
doi: 10.11728/cjss2008.03.203
Abstract:
Since the Cluster passes through the crucial regions where the solar wind and the magnetosphere interact, this paper compares the empirical magnetic field T96, T01 models and the paraboloid A2000 model with Cluster magnetic data. The reliability of the three models for different orbit whose perigee is either on the dayside or on the nightside of the magnetosphere is examined. The results show that, (1) Magnetic filed near the perigees of Cluster orbits is mainly influenced by Birkland currents, the T01 and T96 models give a good estimation of the location of passage through the large-scale currents, while the modeled magnitude being not accurate, and due to the absence of II region field-aligned current, the A2000 model can't correctly predict the disturbance of magnetic filed near the perigee; (2) For cases of 0>Dst>-100 nT, the reliability of T96 is comparable to that of T01, while due to the absence of the partial ring current, the T96 model can't correctly reproduce the magnetic field near the dayside perigee close to the dusk region; (3) The residual RMS deviation of the T96 and T01 models is about 40 % of the average magnitude of the observed external field for nightside perigee cases, while due to the effect of currents near cusp, that increases to 50 % for dayside perigee cases. Contrastively, the residual RMS deviation of the A2000 model is apparently larger, which is 58 % of the observed field.