such as that reported by Dolginov et al. (1973). However, for the dipole moment reported of 2.6 X 1022 G cm3, the atmospheric asymmetries may still dominate any effects due to the dipole rotation and control the dynamics of shock formation (Rassbach et al., 1974).
The reported observation of constant magnetic field direction within the Martian nightside obstacle boundary offers a stronger argument in support of an intrinsic Martian field than the observations of shock variability. A further argument for at least a weak intrinsic field is the absence of evidence of downward ionospheric convection (scale height depression by solar-wind pressure) in the Martian dayside atmosphere such as that proposed by Bauer and Hartle (1974) to explain Mariner—10 observations of Venus.
- ACKNOWLEDGMENTS
The author is grateful to R. A. Wolf, F. C. Michel, R. E. Daniell, Jr., and K. I. Gringauz for their pertinent comments and suggestions. This work was supported by the Atmospheric Sciences Division of the National Science Foundation, N.S.F. Grant DES74-19668.
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