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2021 |
The Universal Time Variations of the Intensity of Afternoon Aurora in Equinoctial Seasons The afternoon auroral emissions are investigated in the equinoxes for geomagnetically quiet conditions (Kp = 1) using auroral images from ultraviolet imager (UVI) aboard the Polar satellite. They are compared with solar illumination effects (the solar zenith angle [SZA] and the consequent ionospheric conductivity) and the dipole tilt angle, as well as the observational region 1 upward field-aligned currents (FACs) from AMPERE data. The averaged afternoon auroral emissions have pronounced universal time (UT) variations with valley (2.8 photons/cm2/s) at around 01:00–03:00 UT and peak (4.7 photons/cm2/s) at around 17:00–19:00 UT. They generally vary with the solar illumination, the dipole tilt angle and the observed region 1 upward FACs as a function of UT. The afternoon auroral intensity is anticorrelated with the SZA and positively proportional to the solar EUV-produced Pedersen conductivity, region 1 upward FACs and dipole tilt angle. Additionally, they depend weakly on solar flux under geomagnetically quiet conditions. These results suggest that in the afternoon auroral region, the peak auroral emissions are closely associated with the peak conductivity and the maximum upward FACs. Other mechanisms, such as the dipole tilt angle, may also contribute. Further comparison between the northern afternoon aurora and the FACs in the two conjugate hemispheres suggests little contributions on the auroral UT variations from the interhemispheric FACs in the equinoxes. Wang, Lingmin; Luan, Xiaoli; Lei, Jiuhou; Lynch, Kristina; Zhang, Binzheng; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021   DOI: 10.1029/2020JA028504 afternoon auroral emissions; auroral hot spots; dipole tilt angle; region 1 upward FACs; solar zenith angle; UT variations |
We advance the modeling capability of electron particle precipitation from the magnetosphere to the ionosphere through a new database and use of machine learning (ML) tools to gain utility from those data. We have compiled, curated, analyzed, and made available a new and more capable database of particle precipitation data that includes 51 satellite years of Defense Meteorological Satellite Program (DMSP) observations temporally aligned with solar wind and geomagnetic activity data. The new total electron energy flux particle precipitation nowcast model, a neural network called PrecipNet, takes advantage of increased expressive power afforded by ML approaches to appropriately utilize diverse information from the solar wind and geomagnetic activity and, importantly, their time histories. With a more capable representation of the organizing parameters and the target electron energy flux observations, PrecipNet achieves a \textgreater50\% reduction in errors from a current state-of-the-art model oval variation, assessment, tracking, intensity, and online nowcasting (OVATION Prime), better captures the dynamic changes of the auroral flux, and provides evidence that it can capably reconstruct mesoscale phenomena. We create and apply a new framework for space weather model evaluation that culminates previous guidance from across the solar-terrestrial research community. The research approach and results are representative of the “new frontier” of space weather research at the intersection of traditional and data science-driven discovery and provides a foundation for future efforts. McGranaghan, Ryan; Ziegler, Jack; Bloch, Téo; Hatch, Spencer; Camporeale, Enrico; Lynch, Kristina; Owens, Mathew; Gjerloev, Jesper; Zhang, Binzheng; Skone, Susan; Published by: Space Weather Published on: YEAR: 2021   DOI: 10.1029/2020SW002684 space weather; magnetosphere-ionosphere coupling; data science; evaluation; machine learning; particle precipitation |
2016 |
RENU 2 UV Measurements of Atomic Oxygen in the Cusp Region Fritz, Bruce; Lessard, Marc; Paxton, Larry; Cook, Timothy; Lynch, Kristina; Clemmons, James; Hecht, James; Hysell, David; Crowley, Geoff; Published by: Published on: |
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