On deriving incident auroral particle fluxes in the daytime using combined ground-based optical and radar measurements

Abstract

[1] Particle energies and fluxes have predominantly been measured from instruments onboard satellites. In this study, we use daytime ground-based oxygen redline emission measurements, along with the ionospheric electron density, and electron temperature profiles measured from the incoherent scatter radar, and a physics-based modeling approach to derive the energy and flux of particles incident over Boston during the storm of 30 October 2003. We find that the characteristic energy and the associated flux vary between 0.07-5.7 keV and 0.5-130 mW m −2 , respectively, during the intense magnetic disturbance that brought aurora to midlatitudes. Such an approach not only offers another method to estimate the incident particle energies and fluxes but also enhances our understanding on the channels of energy deposition in the upper atmospheric region, especially during magnetic disturbances, about which database is poor.Citation: Pallamraju, D., S. Chakrabarti, and S. C. Solomon (2011), On deriving incident auroral particle fluxes in the daytime using combined ground-based optical and radar measurements,

Derivation of the Energy and Flux Morphology in an Aurora Observed at Midlatitude Using Multispectral Imaging

“…Pallamraju et al () had only the red line brightness measurements and so used the electron density profile ( N e ) from ISR measurements to derive energies of the precipitating electrons. GLOW model red line brightness (at the derived energies) was then constrained with measurements to derive energy fluxes.…”

“…The hmF2 is sensitive to changes in energy of the precipitating electrons because this determines where the electrons are stopped (Rees, ). Pallamraju et al () used this concept to derive the energy of precipitating electrons. Similarly, Rees and Luckey () utilize red to blue line brightness ratios to infer the energy of the precipitating electrons.…”

“…Thus, their brightness ratio is sensitive to the energy of precipitating electrons. Also, as all the brightnesses increase with flux, Pallamraju et al () and Rees () use the red and the blue brightnesses, respectively, to estimate the flux. In addition, Grubbs, Michell, Samara, Hampton, Hecht et al () use the OI 844.6 to green line ratio and the blue line brightness in conjunction with a modified version of the GLOW model to derive energy and flux during an auroral event.…”

“…The energy and flux have also been inferred remotely by satellite‐based UV measurements (see, for example, Christensen et al, ). Electron energies and fluxes have also been estimated from the ground using incoherent scatter radar (ISR; Semeter & Kamalabadi, ) and combined optical and radar measurements (Pallamraju et al, ). In addition, a method for deriving precipitating electron energy fluxes by solving a large linear inversion problem based on multiwavelength (red and green lines) all‐sky imagers was presented by Janhunen ().…”

“…Thus, the peak height of the electron density profile depends on the energy of precipitating electrons during such events. Using this concept, Pallamraju et al () derived energies of the precipitating electrons using the F2 peak heights (hmF2) from nearby ISR measurements for an auroral event over Boston, MA. The energy fluxes were then derived by matching the measured red line brightness to that predicted by a physics‐based electron transport model called GLobal airglOW (GLOW) (Bailey et al, ; Solomon et al, ; Solomon & Abreu, ).…”