Incoherent scatter radar observations of 10–100 keV precipitation: review and outlook

Abstract In this chapter, we review incoherent scatter radar-based techniques for quantifying energetic particle precipitation that impacts the E- and D-regions of the ionosphere and the middle and upper atmosphere. We review particle transport models and techniques, relevant E- and D-region chemistry models, and methods to estimate the differential number flux of energetic precipitation based on incoherent scatter radar observations of enhanced electron density. Previous incoherent scatter radar results of energetic particle precipitation associated with pulsating aurorae and auroral substorms are reviewed. Routine D-region observations have been conducted at the Poker Flat Incoherent Scatter Radar since 2007, and since 2015, this radar has been run during intervals in conjunction with the Van Allen Probes and the Arase satellite. We present preliminary results from a case study from January 13, 2015, which shows energetic precipitation coincident with a near conjunction with the Van Allen Probes. We conclude with open questions that can be addressed using incoherent scatter radar.