OpenGGCM Simulations of Bursty Bulk Flows: Observational Signatures

A significant component of the convection in the Earth's plasma sheet occurs in the form of short ( 10-min) bursts of high speed plasma moving earthward; these events have been called "Bursty Bulk Flows" (BBFs). While these events have been observed in situ directly with satellites, the observational characteristics are not unique. There exists a standard profile, derived from statistical analysis of many events, such as an associated depolarization of the field, and a drop in plasma density; however, many BBF observations deviate from that picture. In order to investigate varying BBF satellite signatures, we use OpenGGCM simulations, which produce realistic looking BBFs. By generating virtual observations at different locations relative to the BBFs, we show that the same BBF produces highly varying signatures depending on the location of the observing satellite. This results mainly from the fact that BBFs are not simple one-dimensional structures as they are often depicted in the literature, but rather following more complicated paths in the plasma sheet. In particular, a BBF may move sideways over a s/c, producing a large velocity signature, but not much of a magnetic field signature. Likewise, it is also possible for a s/c to only see a brief encounter with the BBF's head, i.e., the dipolarization front, in which case there is a clear magnetic field signature, but less of a velocity signature. In this presentation, we will present a comprehensive study of the possible BBF signatures, which will aid in the interpretation of observations.