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A recently developed method for recovering two‐dimensional (∂/∂ z ≈ 0), time‐stationary magnetic field structures in the magnetopause is improved and further applied to two complete magnetopause crossings by the spacecraft AMPTE/IRM. The technique consists of solving the Grad‐Shafranov (GS) equation for magnetohydrostatic structures as a Cauchy problem, using measured data along a spacecraft trajectory through the structure as spatial initial values. We have implemented the following improvements: (1) allowing for different functional behavior of the transverse pressure, P t = p + B z 2 /2μ 0 , versus A , the calculated magnetic potential, on the magnetosphere and the magnetosheath side of the magnetopause; (2) allowing for change in the velocity of the magnetopause structures as they move past the spacecraft by using a time‐varying deHoffmann‐Teller (HT) frame velocity; (3) suppressing numerical instabilities and thus extending the integration domain by constraining the behavior of the total pressure. Results from two AMPTE/IRM events show layered and asymmetric structures on the two sides of the magnetopause owing to double‐branched behavior in p ( A ) as well as B z ( A ). A time‐varying HT frame results in a curved spacecraft trajectory through the magnetopause. The reconstructed field structures show important changes in size but only slight changes in configuration. The use of a time‐varying HT frame for determination of time‐varying magnetopause motion is discussed.
Hu et al. (Wed,) studied this question.