"transmissivity" properties of precipitating auroral electron energy and number flux the objective of the proposal is to determine and understand the variability in the ratio of the downgoing electron…

This federal contract award, with a ceiling value of $493,454.00, was granted by the National Aeronautics and Space Administration (NASA) to the Regents of the University of Minnesota, doing business as the Office of Sponsored Projects Administration. The contract, which does not have a set-aside designation, is for research focused on understanding the "transmissivity" or variability in the ratio of downgoing to absorbed energy flux of auroral electron precipitation and its impact on magnetosphere-ionosphere coupling processes. The University of Minnesota, as a major land-grant research institution, will utilize its expertise in fields like space physics and atmospheric science to model electron distributions, compare them to spacecraft data, and statistically analyze the energy and particle flux into the ionosphere under different conditions. This work is intended to improve the accuracy of related modeling and understanding of energy transfer in the magnetosphere-ionosphere system.

"transmissivity" properties of precipitating auroral electron energy and number flux the objective of the proposal is to determine and understand the variability in the ratio of the downgoing electron energy (and number) flux to the net flux absorbed in the ionosphere, the "transmitivity, for auroral electron precipitation. Our hypothesis is that this ratio of downgoing to absorbed energy flux has substantial variability. Our initial analysis indicates that the statistical average of this "transmitivity" can vary by a factor on the order of two for different precipitation mechanisms and/or magnetospheric/ ionospheric conditions. Since electron precipitation accounts for ~80-85% of the energy input into the ionosphere [newell ET AL., 2009], such variance in the downgoing to absorbed energy flux ratio has an extremely large impact on understanding of m-i coupling processes and energy/ particle transfer in the m-i system and on the accuracy of related modeling. We propose to investigate the physics that results in the flux values, specifically focusing on the electron distributions to connect theory and measurements. We will produce modeled electron distributions for various mechanisms and conditions, based on test particle ensembles, and compare them with actual electron distribution measurements from the fast spacecraft under different conditions. By doing this we will address our specific science goals, in summary: 1) determining how the distributions, and therefore the "transmitivity" varies by mechanism and conditions; 2) determining the extent to which the fractions of m-i flux transfer are related to the individual mechanisms in multiple concurrent precipitation mechanism events can be determined; and 3) determining the statistical "transmitivity" and net electron energy (and number) flux into the ionosphere by location and solar input, magnetospheric and ionospheric conditions. This last specific goal, #3, will be accomplished by statistically analyzing the fast electron distribution data for the entire fast lifetime (~13 years).