Statistical Occurrence and Distribution of High-Amplitude Whistler Mode Waves in the Outer Radiation Belt

We present the first statistical analysis with continuous data coverage and nonaveraged amplitudes of the prevalence and distribution of high-amplitude (>5 mV/m) whistler mode waves in the outer radiation belt using 5 years of Van Allen Probes data. These waves are most common above L = 3.5 and between magnetic local time of 0–7 where they are present 1–4% of the time. During high geomagnetic activity, high-amplitude whistler mode wave occurrence rises above 30% in some regions. During these active times the plasmasphere erodes to lower L and high-amplitude waves are observed at all L outside of it, with the highest occurrence at low L (3.5–4) in the predawn sector. These results have important implications for modeling radiation belt particle interactions with chorus, as large-amplitude waves interact nonlinearly with electrons. Results also may provide clues regarding the mechanisms which result in growth to large amplitudes.