International audienceEnhancements of drift-loss cone fluxes in the inner radiation belt have been observed to coincide with the geographic location of the powerful VLF transmitter NWC. In this paper we expand upon the earlier study to examine the occurrence frequency of drift-loss cone enhancements observed above transmitters and the intensity of the flux enhancements and to demonstrate the linkage to transmitter operation. Our study has confirmed the strong dependence that these enhancements have upon nighttime ionospheric conditions. No enhancements were observed during daytime periods, consistent with the increased ionospheric absorption. We have also confirmed the persistent occurrence of the wisp features east of the NWC transmitter. The enhancements are initially observed within a few degrees west of NWC and are present in 95% of the nighttime orbital data east of the transmitter for time periods when the transmitter is broadcasting. No enhancements are observed when NWC is not broadcasting. This provides conclusive evidence of the linkage between these drift-loss cone electron flux enhancements and transmissions from NWC. When contrasted with periods when NWC is nonoperational, there are typically ∼430 times more 100–260 keV resonant electrons present in the drift-loss cone across L = 1.67–1.9 owing to NWC transmissions. There are almost no wisp-like enhancements produced by the transmitter NPM, despite its low-latitude location and relatively high output power. The lack of any wisp enhancement for L < 1.6 suggests that nonducted propagation is an inefficient mechanism for scattering electrons, which explains the lower cutoff in L of the NWC-generated wisps and the lack of NPM-generated wisps

[1] The behavior of high-energy electrons trapped in the Earth's Van Allen radiation belts has been extensively studied, through both experimental and theoretical techniques. While the evidence for whistler induced electron precipitation (WEP) from the radiation belts is overwhelming, and the mechanisms behind WEP are well understood, the overall significance of WEP on radiation belt loss rates has not been clear. In this paper we investigate the L-shell variation and significance of WEP-driven loss of Van Allen belt electrons by combining in situ measurements of electron precipitation, local WEP rates determined from Trimpi perturbations, and global lightning distributions. Our modeling suggests that long-term WEP driven losses are more significant than all other inner radiation belt loss processes for electron kinetic energies in the range $50-150 keV in the L-shell range L = 2-2.4. These calculated lifetimes are comparable to the observed decay rates of artificially injected high-energy electrons. The upper energy limit of the WEP significance range increases with decreasing L to $225 keV at L = 2. For electron energies above this range manmade VLF transmitters and plasmaspheric hiss should dominate over all other loss processes. However, as our lifetimes are based on rather conservative parameter estimates, these conclusions should represent the lower bounds for the energy ranges over which WEP losses are significant. For lower L-shells the coupling of lightning activity to the production of WEP events rapidly decreases, such that by L $ 1.7 WEP will be unimportant in the overall loss processes.INDEX TERMS: 2716 Magnetospheric Physics: Energetic particles, precipitating; 2730 Magnetospheric Physics: Magnetosphere-inner; 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions; 2483 Ionosphere: Wave/particle interactions; 3304 Meteorology and Atmospheric Dynamics: Atmospheric electricity; KEYWORDS: whistlers, inner radiation belt, electron precipitation, Trimpi, lightning, wave-particle interaction Citation: Rodger, C. J., M. A. Clilverd, and R. J. McCormick, Significance of lightning-generated whistlers to inner radiation belt electron lifetimes,

Manmade control of the radiation belts for the protection of space‐based infrastructure has been suggested on the basis of theoretical calculations. In this paper we put forward an experimental test of the relative importance of either whistler‐induced electron precipitation (WEP) or manmade VLF transmitters as the most significant inner radiation belt loss mechanisms for 2 < L < 2.4. The experimental identification of seasonality in inner radiation belt electrons lifetimes would provide strong evidence for the relative significance of WEP‐ or manmade transmitter‐driven losses depending on the relative phasing found.

This study provides prevalence data for NUG in the British Armed Forces and description of its treatment and associated risk factors. Oral hygiene and smoking must be addressed in patients with NUG and prescribing protocols should be carefully followed.

It has been suggested that E × B mixing of magnetospheric plasma can lead to geomagnetic field‐aligned ionization enhancements termed whistler ducts. DC electric fields from thunderstorms have been put forward as the source of the required radial electrostatic field. Recent experimental observations have indicated that quasi‐static radial thunderstorm electric fields are not responsible for whistler duct formation. This evidence appears to be in contradiction to the current theoretical calculations. In this paper we reconsider whistler duct formation through quasi‐static thunderstorm electric fields. Both the charge distributions and ionospheric profiles previously used are based on rather dated assumptions. We find that more realistic thunderstorm charge distributions in conjunction with the earlier ionospheric profiles produce high‐altitude electric fields that are of insufficient strength, given average thunderstorm effective charge, to create ducting within a reasonable time period. This is, however, not confirmed when the same charge distributions are examined using a more modern ionospheric profile based on international standard models for the ionosphere and neutral atmosphere. In this case some charge distributions will lead to realistic whistler duct creation. Our modeling suggests that quasi‐electrostatic radial fields from thunderstorms could drive whistler duct formation in some situations.