A Polar-Cap Patch Detection Algorithm for the Advanced Modular Incoherent Scatter Radar System

We introduce an algorithm to detect polar-cap patches in an Advanced Modular Incoherent Scatter Radar data set, using the Resolute Bay Incoherent Scatter Radar—North. Patches are detected by comparing plasma density (n_e) measurements along each radar beam to a 30-min running average of the median n_e within the field-of-view. The algorithm is tested and shown to be an effective tool for polar-cap patch studies. It is then used to conduct a survey of patches over Resolute Bay for two separate periods of time centered on March and December of 2010. The survey shows that polar-cap patches are almost always present in both sunlit and nighttime conditions. However, the population is subdued during the day. The patch densities are found to vary by as much as an order of magnitude throughout the day. Their ion temperature is relatively constant, only varying by 100 K between the sunlit and nighttime conditions. By contrast, their electron temperature is very sensitive to the solar zenith angle and changes dramatically around sunrise.