Cross-Shock Potential in Rippled vs. Planar Quasi-Perpendicular Shocks Observed by MMS

International audienceThe unprecedented detail of measurements by the four Magnetospheric Multiscale (MMS) spacecraft enable deeper investigation of quasi‐perpendicular collisionless shocks. We compare shock normals, planarities, and Normal Incidence Frame (NIF) cross‐shock potentials determined from electric field measurements and proxies, for a subcritical (Fast Magnetosonic Mach number MF = 1.05 ± 0.05) interplanetary shock and a supercritical bow shock (MF = 2.13 ± 0.04). The low‐Mach shock's cross‐shock potential was 26±6V. The shock scale was 33km, too short to allow comparison with proxies from ion moments. Proxies from electron moments provided potential estimates of 40±5V. Shock normals from magnetic field minimum variance analysis were nearly identical, indicating a planar front. The high‐Mach shock's cross‐shock potential was estimated to be from 290 to 440V from the different spacecraft measurements, with shock scale 120km. Reflected ions contaminated the ion‐based proxies upstream, whereas electron‐based proxies yielded reasonable estimates of 250±50V. Shock normals from electric field maximum variance analysis differed, indicating a rippled front