Models of the External Source Contribution to Magnetospheric Magnetic Fields for CRRES Data Analysis.

摘要

The Olson-Pfitzer tilt dependent, the Mead-Fairfield, the Tsyganenko-Usmanov, the Tsyganenko 1987, the Olson-Pfitzer dynamic, and the Stern external magnetic field models are reviewed for their appropriateness for use in analysis of data from the Combined Release and Radiation Effects Satellite (CRRES). Descriptions of the models and their derivations are given. The Stern model requires considerably more computation time than the others. The L-parameter computed with an internal plus external field deviates considerably from that obtained with the internal field alone at the larger radial distances in CRRES's range. The models also differ noticeably from one another. The magnetic field magnitudes computed from the models during a SCATHA orbit over a magnetically quiet period agree well with SCATHA magnetometer observations. The Olson-Pfitzer dynamic model best tracks the data. However during the subsequent orbit, none of the models depict the large observed substorm- associated depression. The equatorial midnight field depression predicted by the Olson-Pfitzer dynamic model at zero dipole tilt is larger at small distances than that implied by averaged AMPTE and OGO measurements; the Stern and Olson-Pfitzer tilt dependent models are in good agreement with the measurements, while the other models predict smaller depressions. It is concluded that the Olson-Pfitzer dynamic model is the best to use for CRRES, primarily because of its parameterization and its superior data base in the CRRES range. (JHD)