Observational Results of Diurnal Variation in Quiet Time Inner Plasmasphere Equatorial Noise Leading to Post-Midnight Ion Loss

Abstract:

After the discovery of the plasmaspheric post-midnight 1-10 eV ion loss between L =2 and L =3, we have expanded upon these results and connected the observed ion loss with changes in plasma wave activity. Using the Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) and the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instruments, we observed that diurnal variation in EMFISIS equatorial noise measurements was consistent with HOPE H+ thermal ion measurement variations. Through statistical studies and case studies, we present how enhanced dayside equatorial noise heats via cyclotron resonance to form the 1-10 eV ion population of the inner plasmasphere during quiet time.