Determination of the plasmapause boundary using ground magnetometer field line resonances, satellite observations, and modeling

The plasmapause boundary layer (PBL) separates the cold and dense plasmaspheric plasma from the more tenuous and hot plasma sheet plasma and organizes the spatial distribution of ULF and VLF waves that can contribute to acceleration or loss processes of radiation belt particles through wave-particle interactions. The PBL has been traditionally determined by in situ observations and can be given by empirical models. Recent work has shown that a mid-latitude chain of well-spaced ground magnetometers can also determine the PBL boundary location. Spectral properties, like the cross-phase reversal between two stations closely aligned in latitude, have been shown to indicate the presence of a sharp PBL. We show here an example of such a PBL identification during the moderate storm of Nov 9-12, 2006. We combine observations from the SAMBA (South American Meridional B-field Array), MEASURE (Magnetometers along the Eastern Atlantic Seaboard for Undergraduate Research and Education), McMAC (Mid-continent Magnetoseismic Chain), and CARISMA ground magnetometer chains covering L values from L=2 to L=5 to statistically determine how commonly the PBL is determined from ground magnetometers. In our initial study we examine observations from June to December, 2006. We compare our PBL determinations with the determination of the same boundary from the Defense Meteorological Satellite Program (DMSP) satellites, based on the H+ density observations, which have been shown to accurately identify the PBL from a low-Earth orbiting satellite. We also compare our PBL identification with those determined from a global GPS TEC map and GPS TEC tomography technique used by a chain of ground GPS receivers. Finally, we compare our observations with results from the Dynamic Global Core Plasma Model (DGCPM), as well as existing empirical models based on in situ observations.