Engineering topics

Newman, T. S.

Publications and source records attributed to Newman, T. S..

4 records

NASA NTRS2006

Plasmapause Equatorial Shape Determination via the Minimum L Algorithm: Description and Evaluation

The Minimum L Algorithm for determining the equatorial shape of the plasmapause using NASA IMAGE Extreme Ultraviolet (EUV) imagery is described and analyzed. The algorithm operates without human intervention given a single EUV image in which the plasmasphere silhouette boundary has been identified. For each line of sight (LOS) through pixels on the 13 plasmasphere silhouette boundary, the algorithm first finds all magnetic dipole 14 field lines intersected by the LOS and then returns as the plasmasphere s boundary the field line with the minimum L value. The analysis considers the reasonableness, applicability, and accuracy of the algorithm and contrasts it with 17 the well-known Edge Algorithm is also introduced. Application of all three algorithms to real EUV imagery is demonstrated.

Newman, Timothy S.↗

NASA NTRS2005

Oriented Connectivity-Based Method for Segmenting Solar Loops

A method based on oriented connectivity that can automatically segnient arc-like structures (solar loops) from intensity images of the Sun's corona is introduced. The method is a constructive approach that uses model-guided processing to enable extraction of credible loop structures. Since the solar loops are vestiges of the solar magnetic field, the model-guided processing exploits external estimates of this field s local orientations that are derived from a physical magnetic field model. Empirical studies of the method s effectiveness are also presented. The Oriented Connectivity- Based Method is the first automatic method for the segmentation of solar loops.

Lee, J. K.↗

NASA NTRS2002

Self-Consistent Magnetosphere-Ionosphere Coupling: Theoretical Studies

A self-consistent ring current (RC) model has been developed that couples electron and ion magnetospheric dynamics with the calculation of the electric field. Two new features were taken into account in order to close the self-consistent magnetosphere- ionosphere coupling loop. First, in addition to the RC ions, we solve an electron kinetic equation in our model. Second, using the relation of Galand and Richmond [2001], we calculate the height integrated ionospheric conductances as a function of the precipitated high energy magnetospheric electrons and ions that are produced by our code. To validate the results of our model we simulate the magnetic storm of May 2, 1986, a storm that has has been comprehensively studied, and compare our results with different theoretical approaches. The self-consistent inclusion of the hot electrons and, their effect on the conductance results in deeper penetration of the magnetospheric electric field. In addition, a slight westward rotation of the potential pattern (compared to previous self-consistent results) is evident in the inner magnetosphere. This changes the hot plasma distribution, especially by allowing increased access of plasma sheet ions and electrons to low L shells.

Khazanov, G. V.↗

NASA NTRS2002

Self-Consistent Magnetosphere-Ionosphere Coupling

A self-consistent ring current (RC) model has been developed that couples electron and ion magnetospheric dynamics with the calculation of the electric field. Two new features were taken into account in order to close the self-consistent magnetosphere-ionosphere coupling loop. First, in addition to the RC ions, we have solved an electron kinetic equation in our model. Second, using the relation of Galand and Richmond, we have calculated the height integrated ionospheric conductances as a function of the precipitated high energy magnetospheric electrons and ions that are produced by our model. To validate the results of our model we simulate the magnetic storm of May 2, 1986, a storm that has been comprehensively studied by Fok et al., and have compared our results with different theoretical approaches. The self-consistent inclusion of the hot electrons and their effect on the conductance results in deeper penetration of the magnetospheric electric field. In addition, a slight westward rotation of the potential pattern (compared to previous self-consistent results) is evident in the inner magnetosphere. These effects change the hot plasma distribution, especially by allowing increased access of plasma sheet ions and electrons to low L shells.

Six, N. Frank↗