NTRS - NASA Technical Reports Server

Back to Results
High-Time-Resolution Study of Magnetic Holes in the Solar WindThe objectives of this investigation are to determine the internal plasma structure of kinetic-scale and larger scale magnetic holes, and to determine their stability, their source mechanism(s), and their spatial extent. It is also of importance to determine the relationship between kinetic-scale holes and long-duration holes. As smaller and smaller magnetic depressions are investigated in order to make this a complete study, a robust criterion is necessary for distinguishing magnetic holes from random or unresolvable fluctuations in the interplanetary magnetic field. In order to resolve this ambiguity, we obtained from the MFI experiments magnetic field measurements from the WIND spacecraft at a time resolution of 46 to 184 ms over certain periods. We have also devised a measure of certainty for magnetic hole detections. The certainty factor, q, is defined as the difference between the mean magnetic field in the hole and the local magnetic field, in units of the local standard deviation of the field strength. For fullest generality, it is necessary to calculate this q over the range of available scales of interest, from 60 ms up to 300 s. This technique establishes a two dimensional matrix of relative probabilities that a hole of some duration (d) might exist in the data set at a given time (t). In identifying q-peaks in time and duration, we also come upon a natural method for distinguishing holes with internal structure from multiple holes in close proximity or holes nested inside of others. If two q-peaks are more than a half-width apart, they are simply said to be separate events.
Document ID
Document Type
Lazarus, Alan (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Kasper, Justin (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Stevens, Michael (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Solar Physics
Report/Patent Number
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
Document Inquiry