Multipoint Observations of a SLAMS Evolution and Its Merger With Whistler Waves

We report multipoint observations of a merger between a Short Large-Amplitude Magnetic Structure (SLAMS) and 1-Hz whistler wave packets upstream of Earth's quasi-parallel bow shock. Using high-resolution data from the Magnetospheric Multiscale (MMS) mission in a string-of-pearls configuration, we track the SLAMS as it evolves, exhibiting enhanced magnetic field strength, increasing spatial scale, variable ion reflection at the ramp, and increasingly complex morphology. The whistler wave packets show distinct propagation properties, propagating at a different velocity from the SLAMS and approaching it from upstream. Eventually, the SLAMS merges with the wave packets, altering its structure and forming a new ramp characterized by an intensified magnetic field and plasma density. These observations demonstrate how SLAMS and wave packets can coexist and interact, leading to changes in local plasma conditions and revealing the complexity and dynamic nature of bow shock transitions.