NSWP: Poynting and Kinetic-Energy Flux Derived from the FAST Satellite: an Empirical Model

Sri International, Menlo Park CA

Investigators

Abstract

The primary purpose of this project is to develop improved models of the energy input from the magnetosphere to the thermosphere at high latitudes using five years of data from the Fast Auroral Snapshot Explorer (FAST) satellite. Such information is important for accurate modeling and specification of the thermospheric neutral densities and circulation and is a necessary input for space weather models. The methodology involves fitting a model directly to measurements of the energy input derived from FAST satellite observations with good time and space resolution. More than 20,000 satellite orbits are available for analysis. The data will be binned according to geophysical parameters. An analytical model based on a low order spherical harmonic expansion will then be fit to the binned data. The model will provide spatial maps of the average energy input and predictions of the energy input as a function of scale size in two dimensions for particular values of model parameters. The energy arriving from the magnetosphere is mostly in the form of Poynting flux traveling along magnetic field lines and partially converted to kinetic energy in the auroral acceleration region. Separate models of the relative spatial distribution of kinetic energy and Poynting flux below the auroral acceleration region will also be produced. The particular science question being addressed is whether the localization of energy inputs in the auroral region is imposed by the magnetosphere or is affected by the auroral acceleration region. If the latter mechanism is important, investigation will be made of whether the auroral acceleration region broadens the spatial extent of the region of greatest energy input. The project has several broader impacts: The models produced will quantify the energy budget for solar-wind-driven heating of the thermosphere, in both the spatial and spatial frequency domains. Energy convergence and conversion in the auroral acceleration region will be quantified using in-situ measurements. The models will be made available to the community and can be used to drive models of the global temperature, circulation, and density of the thermosphere, the specification of which is a key goal of the National Space Weather Program. A large part of the research will be performed by senior undergraduate students from Worcester Polytechnic Institute.