Two- and one-dimensional fully electromagnetic, bounded, particle (for both electrons and ions) codes are used in order to study electron dynamics in collisionless magnetosonic shocks propagating in supercritical regime and quasi-perpendicular direction (90¿>&thgr;0>45¿); &thgr;0 is the angle between the shock normal and the upstream magnetic field. The purpose of the study consists in comparing electrons behavior in one-dimensional (''pseudo-oblique'') nonresistive shocks and in two-dimensional resistive oblique shocks. Resistive effects related to plasma microinstabilities can be self-consistently included in two-dimensional particle codes in contrast with one-dimensional particle codes. Present two-dimensional results reproduce local electron distribution functions (in particular, downstream ''flat tops'') in a self-consistent way and in good agreement with observational results. On the other hand, one-dimensional results exhibit either local enlarged Maxwellian distributions with a partial tail, or a flat top distribution according to the particle density n. These results emphasize that (1) the differences observed between one- and two-dimensional codes may be explained in terms of a critical particle density nc used in the one-dimensional code; (2) the evidence of flat tops in both two- and one-dimensional results (provided that n>nc) proves that the macroscopic potential jump at the shock front is mainly responsible for their formation; (3) microscopic effects (herein related to the self-consistent cross-field/field-aligned currents instabilities) may represent a complementary mechanism for filling the flat top distribution; (4) some relaxation of the unstable electron flat top distribution (T∥/T⊥≫1) is observed when penetrating further into the downstream region, which means that the main filling mechanisms are localized in the ramp of the shock.

Moreover, a detailed study of two-dimensional results shows that both resistive and nonresistive configurations can be easily distinguished for &thgr;0≈90¿, but not any more for large deviations of &thgr;0 from 90¿, for which the self-consistent magnetic field rotates noticeably out of the coplanarity plane at the shock front. ¿ American Geophysical Union 1994