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NASA NTRS2017

Ionospheric Slant Total Electron Content Analysis Using Global Positioning System Based Estimation

A method, system, apparatus, and computer program product provide the ability to analyze ionospheric slant total electron content (TEC) using global navigation satellite systems (GNSS)-based estimation. Slant TEC is estimated for a given set of raypath geometries by fitting historical GNSS data to a specified delay model. The accuracy of the specified delay model is estimated by computing delay estimate residuals and plotting a behavior of the delay estimate residuals. An ionospheric threat model is computed based on the specified delay model. Ionospheric grid delays (IGDs) and grid ionospheric vertical errors (GIVEs) are computed based on the ionospheric threat model.

Sparks, Lawrence C.↗

NASA NTRS2008

The Formation of Filament Threads in a Sheared Magnetic Field

This slide presentation reviews the mechanism that form the filament threads in the sheared magnetic field of the solar photosphere. There are observations of the filaments, a chart showing the magnetic field configuration for the filaments, and charts that show the thermal instability, and thermal conduction. Discussion of the question "How is it possible for a magnetic field to inhibit heat flow in a coronal plasma without simultaneously restricting the mass flow required for the growth of density condensations?" is reviewed. Equations that are used in the model are given. The characteristics of dynamic condensations are reviewed. There are charts that show the density perturbations for principal dynamic condensation mode and 1st harmonic. The characteristics of the kinematic condensations are also discussed. The types of perturbations that were studied are: (1) Generic perturbation with T(sub 0) < T(sub c) (2) Generic perturbation with T(sub 0) = T(sub c) (3) Random perturbation with T(sub 0)< T(sub c).

condensational instability↗