Imaging Sub-minute Kilometer-Scale PMSE Dynamics and Layering Using a 5-Beam Multistatic Mode with the MAARSY Radar

During the summer of 2025, the Middle Atmosphere Alomar Radar System (MAARSY) was operated to observe polar mesospheric summer echoes (PMSE) in a 5-beam multistatic configuration. The experiment combined 5 beam directions at the MAARSY transmitter with a newly established receiver array near Stø, located approximately 48 km southwest of MAARSY. Multi-beam coherent radar imaging (CRI) was applied for both the bistatic (MAARSY– Stø) link, and the monostatic (MAARSY–MAARSY) link, enabling for the first time, imaging of the same PMSE volume from different viewing geometries. Using CRI with high angular and temporal resolution, four-dimensional (space–time) observations of sub-minute, kilometer-scale dynamics in the mesosphere–lower thermosphere (MLT) region are achieved. The measurements resolve small-scale dynamical processes associated with turbulence, and gravity waves. The occurrence, evolution, and motion of PMSE structures, including layering, and sub-layers are investigated using radar signal strength, line of sight Doppler shift velocities, and spectral widths. In addition, the SIMONe meteor radar network around Andøya is used for providing continuous horizontally resolved background wind fields at PMSE altitudes. The presented case studies provide high resolution temporal and spatial information on kilometer-scale PMSE dynamics and demonstrate the advantage of multi-static imaging for advancing the understanding of MLT instabilities and turbulence.