Statistical Analysis of the Warm Plasma Cloak in the Dayside Magnetosphere: 9 Years of MMS Observations

The warm plasma cloak (WPC) is a plasma population located in the outer magnetosphere. It is composed primarily of electrons and H+ ions with energies of tens to hundreds electronvolts and can contain significant amounts of O+. We conduct a statistical survey of the WPC using 9 years of observations in the dayside magnetosphere from the Magnetospheric Multiscale mission. WPC is found in 51% of the observations and it is 1.6 times more abundant in the dawn than in the dusk sector. O+‐rich WPC is detected in 7.5% of the observations, being 3 times more probable in the dawn sector. We find that after a peak of strong geomagnetic activity, it takes approximately 9 hr to detect the WPC in the dayside magnetosphere.