Relaxation of transient ionization in the lower ionosphere

Abstract

Abstract. This paper presents a set of basic expressions and parameters to describe the relaxation of ionization in the upper atmosphere and lower ionosphere. Both spatial (diffusion) and chemical loss are included, along with the varying electrical conductivity caused by changing electron density and temperature. In particular, masonable values for the attachment rates and recombination coefficients at these high altitudes are discussed. Example calculations are given involving studies into red sprites. However, the modeling and parameters are not restricted to these events, and might well be useful in a number of other modeling problems.

Decay of whistler‐induced electron precipitation and cloud‐ionosphere electrical discharge Trimpis: Observations and analysis

“…For CID Trimpis, the delay (sferic to onset) may be as much as 100 ms if sprite plasma is so hot as to make it transparent to VLF. Although the hot electrons cool to almost ambient in <1 ms at 50 km, the cooling time is -100 ms at 85 km [Rodger et al, 1998c], so the rise time of CID Trimpis would be expected to be slower than 20 ms. One might expect the risetime of WEP Trimpis to be determined by the duration of the pulse of precipitating electrons, which is of the order of 300 ms [Inan et al, 1989]. However, the risetimes of WEP Trimpis that we consider in section 4 appear to be >1 s, suggesting precipitation over a range of latitudes due to multipath or non- The directions of arrival (DoA) of the NWC signal scattered off each CID (sprite plasma), deduced from both the difference in phase at spaced receivers and by PVDF at one or both sites, were within -6 ø of the NWC direction.…”

Investigating radiation belt losses though numerical modelling of precipitating fluxes

“…As such, the simulated ionospheric electron density will relax towards the ambient profile from any perturbed state. The loss rates given by the Rodger et al (1998) expressions depend on the temperature of the electrons and neutrals present and on the instantaneous electron density. While WEP events are likely to cause significant changes in electron temperature, these will be shortlived in comparison with modifications to the electron density (Rodger et al, 1998).…”

“…This position and ionospheric modification size are taken from Clilverd et al (2002), and are determined by observations at multiple Antarctic Peninsula stations. Inside the WEP modified ionospheric region the perturbation to the collision frequency profile is assumed to be zero due to rapid plasma cooling (∼0.1 s at 85 km, and faster for lower altitudes; Rodger et al, 1998), and thus the modification is described solely in terms of perturbations to the electron number density profile dN e (x,y,z), determined in Sect. 2.2 and taken to be independent of horizontal coordinates x and y inside the LIE ellipse.…”

Modeling solar flare induced lower ionosphere changes using VLF/LF transmitter amplitude and phase observations at a midlatitude site

“…For the time development of the e-density profile we use with (Rodger et al, 1998(Rodger et al, , 2007 …”

“…For the recombination coefficient α below 84 km we set with Rodger et al (2007): The attachment coefficient β i during daytime is chosen according to Rodger et al (1998). Because of its dependence on the product of the O 2 and N 2 densities for the process:…”