Unraveling High-Latitude Plasma Density Irregularities: New Techniques and their Scientific Impact

Polar cap patches, or simply "patches", are defined to be plasma density enhancements twice the background, typically 100 km wide.However, this definition mixes different creation mechanisms, including those driven by thermospheric phenomena ("coupling from below") and magnetospheric phenomena ("coupling from above").Furthermore, it is unclear what the "background" plasma density is, given that the high-latitude is frequently highly-structured with enhancements and depletions, which are both disruptive to radio wave propagation and spacecraft.Given these challenges, we question whether the term "patch" remains a scientifically useful classification or whether a more nuanced framework is needed to describe polar cap density structures.