An empirical model of the size and shape of the near‐Earth magnetotail

Abstract

A model of the size and shape of the near‐earth magnetotail which depends upon distance downtail, ρv²sw, and IMF Bz has been developed. This empirical model was developed by first using observations of the magnetic field in the lobe by ISEE‐1 and simultaneous observations of the magnetic field and plasma properties of the solar wind by IMP‐8 to determine the flaring angle of the near‐earth magnetotail in the region −22.5 Re ≤ x ≤ −10 Re. These studies show that the flaring angle depends on x, ρv²sw and IMF Bz. In particular, the median flare angle increases linearly with decreasing Bz when the IMF is southward, while the flare angle is constant when the IMF is northward. The empirical function derived for the flaring angle of the magnetotail is used to determine a relation for the radius of the tail.