An investigation comparing ground‐based techniques that quantify auroral electron flux and conductance

Abstract

We present three case studies that examine optical and radar methods for specifying precipitating auroral flux parameters and conductances. Three events were chosen corresponding to moderate nonsubstorm auroral activity with 557.7 nm intensities greater than 1kR. A technique that directly fits the electron number density from a forward electron transport model to alternating code incoherent scatter radar data is presented. A method for determining characteristic energy using neutral temperature observations is compared against estimates from the incoherent scatter radar. These techniques are focused on line‐of‐sight observations that are aligned with the local geomagnetic field. Good agreement is found between the optical and incoherent scatter radar methods for estimates of the average energy, energy flux, and conductances. The Pedersen conductance predicted by Robinson et al. (1987) is in very good agreement with estimates calculated from the incoherent scatter radar observations. However, we present an updated form of the relation by Robinson et al. (1987), ΣH/ΣP=0.57〈E〉0.53, which was found to be more consistent with the incoherent scatter radar observations. These results are limited to similar auroral configurations as in these case studies. Case studies are presented that quantify auroral electron flux parameters and conductance estimates which can be used to specify the magnitude of energy dissipated within the ionosphere resulting from magnetospheric driving.

Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

“…3j,5b,and 6). These fluxes are in the previously measured ranges (Galand et al 2002;Hecht et al 2008;Kaeppler et al 2015) but much higher than what would be expected at quiet times from the observational evidence. The strong auroral precipitation in the model may be due to diffuse aurora that typically comprises more than 60% of the total auroral power (Newell et al 2009).…”

The effect of ring current electron scattering rates on magnetosphere‐ionosphere coupling

“…where Σ H and Σ P are the Hall and Pedersen conductances, E is the average energy in keV, and E is the energy flux in ergs cm −2 s −1 . Kaeppler et al [2015] recently used incoherent scatter radar observations to verify the Robinson et al formulas, finding good agreement with Pedersen conductance. They also updated the relation to be even more accurate for Hall conductances, which could be used in future studies.…”

“…The electrons scattered into the loss cone by HEIDI were used to calculate ionospheric conductances using the formulation by Robinson et al []: where Σ H and Σ P are the Hall and Pedersen conductances, is the average energy in keV, and ϕ E is the energy flux in ergs cm −2 s −1 . Kaeppler et al [] recently used incoherent scatter radar observations to verify the Robinson et al formulas, finding good agreement with Pedersen conductance. They also updated the relation to be even more accurate for Hall conductances, which could be used in future studies.…”

Electron Energy Spectrum and Auroral Power Estimation From Incoherent Scatter Radar Measurements

“…The steady state models are in active use (Miyoshi et al, 2015) and they are also developed further. For example, Simon Wedlund et al (2013) used the multiplicative algebraic reconstruction technique instead of the maximum entropy method used by Semeter and Kamalabadi (2005), while Kaeppler et al (2015) used the GLOW electron transport model (Solomon et al, 1988) for calculating electron production rates. The steady state models may be considered more realistic than time-dependent ones when one is interested in the energy spectrum in the frame of reference of an advecting flux tube (Semeter & Kamalabadi, 2005).…”

“…The technique used in Turunen et al (2016) is similar to Dahlgren et al (2011) in the sense that it models the time-evolution of electron density within each time step, but it relies on a computationally heavy chemistry modeling utilizing the Sodankylä Ion and Neutral Chemistry (SIC) model, because it is targeted for high-energy (>200 keV) electrons and D region ion chemistry. A recent technique by Kaeppler et al (2015) is a steady state model, but the iterative solution is quite similar with Dahlgren et al (2011). Time-dependent inversion with a simple spectrum model was used by Vierinen et al (2016) to demonstrate benefits of incoherent scatter plasma line observations during auroral precipitation.…”