Assimilative Mapping of Auroral Electron Energy Flux using SSUSI
Lyman-Birge-Hopfield (LBH) Emissions
Abstract
Far ultraviolet (FUV) imaging of the aurora from space provides great
insight into dynamic coupling of the atmosphere, ionosphere and
magnetosphere on global scales. To gain quantitative understanding of
these coupling processes, the global distribution of auroral energy flux
is required, but the inversion of FUV emission to derive precipitating
auroral particles’ energy flux is not straightforward. Furthermore, the
spatial coverage of FUV imaging from Low Earth Orbit (LEO) altitudes is
often insufficient to achieve global mapping of this important
parameter. This study seeks to fill these gaps left by the current
geospace observing system using a combination of data assimilation and
machine learning techniques. Specifically, this paper presents a new
data-driven modeling approach to create instantaneous, global
assimilative mappings of auroral electron total energy flux from
Lyman-Birge-Hopfield (LBH) emission data from the Defense Meteorological
System Program (DMSP) Special Sensor Ultraviolet Spectrographic Imager
(SSUSI). We take a two-step approach; the creation of assimilative maps
of LBH emission using optimal interpolation, followed by the conversion
to energy flux using a neural network model trained with conjunction
observations of in-situ auroral particles and LBH emission from the DMSP
SSJ and SUSSI instruments. The paper demonstrates the feasibility of
this approach with a model prototype built with DMSP data from February
17-23 2014. This study serves as a blueprint for a future comprehensive
data-driven modeling of auroral energy flux that is complementary to
traditional inversion techniques to take advantage of FUV imaging from
LEO platforms for global assimilative mapping of auroral energy flux.