Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere

Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ∼ -130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ∼3.0 Re) and at ionospheric heights (∼840 km) by DMSP F-18. Plasma erosion occurs at both high and low altitudes where the subauroral polarization stream flow overlaps the outer plasmasphere. At ∼20 UT, RBSP-A observed ∼1.2E12 m^-2 s^-1 erosion flux, while DMSP F-18 observed ∼2E13 m^-2 s^-1 sunward flux. We find close similarities at high and low altitudes between the erosion plume in both invariant latitude spatial extent and plasma characteristics. Key Points High-altitude plasmasphere erosion flux has significant magnitude Plasmasphere erosion flux has similar low- and high-altitude characteristics Fluence of ions through cusp and midnight sector exceeds 5E25 ions s^-1