Dynamic relationship between the outer radiation belt and the plasmapause during March–May 2001

The dynamic spatial relationship between the outer radiation belt electrons and the plasmapause during the two‐month period 30 March–30 May 2001 is determined using SAMPEX daily averaged fluxes of 2–6 MeV electrons and IMAGE EUV 10‐min global images of the plasmasphere. In two events, severe erosion moved the plasmapause inside L = 2 and 2–3 days later the outer belt was located in the normal slot region. We determine on what time scale the outer belt location responds to changes in plasmapause location and find the inner extent of the outer belt matched (to within Δ L ≈ 0.1) with a 3.5‐day running average of the plasmapause location, implying a ≥3.5‐day loss time scale from pitch‐angle scattering by plasmaspheric hiss and EMIC waves.