Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere

A case study of lightning, whistlers, and associated ionospheric effects during a substorm particle injection event

Simultaneous ground-based observations of narrowband and broadband VLF radio waves and of cloud-to-ground lightning were made at widely spaced locations during the 1987 Wave-Induced Particle Precipitation (WIPP) campaign, conducted from Wallops Island, Virginia. Based on these observations, the first case study has been made of the relationships among located cloud-to-ground (CG) lightning flashes, whistlers, and associated ionospheric effects during a substorm particle injection event. This event took place 2 days after the strongest geomagnetic storm of 1987, during a reintensification in geomagnetic activity (Kp = 5) that did not affect the high rate of whistlers observed at Faraday Station, Antarctica (L = 2.46). At the time of the injection event, several intense nighttime thunderstorms were located over Long Island and the coast of New England, between 400 km northwest and 600 km north of the region geomagnetically conjugate to Faraday. About two thirds of the CG flashes that were detected in these thunderstorms during the hour following the injection event onset were found to be causatively associated with whistlers received at Faraday. During the same period the amplitude of the 24.0-kHz signal from the NAA transmitter in Cutler, Maine, propagating over the thunderstorm centers toward Wallops Island was repeatedly perturbed in a manner characteristic of previously reported VLF signatures of transient and localized ionization enhancements at D region altitudes. Though such enhancements may have been caused by whistler-induced burst electron precipitation from the magnetosphere, the data in this case are insufficient to establish a clear connection between the NAA amplitude perturbations and the Faraday Station whistlers. In view of the proximity of the NAA great circle path to the storm center, heating of the lower ionosphere by intense radiation from lightning may also have played a role in the observed VLF perturbations. The onset of each of the NAA signal perturbation events coincided with an intense cluster of radio atmospherics. Detailed temporal variations in the ELF (0.3–3 kHz) and VLF (3–30 kHz) power of similar “sferic clusters” correlated well with variations in the power of simultaneous “anomalous” optical events (AOEs) observed by a down-looking photodiode detector on a rocket at altitudes between 150 and 412 km

World-wide lightning location using VLF propagation in the Earth-ionosphere waveguide

Worldwide lightning location (WWLL) using only 30 lightning sensors has been successfully achieved by using only VLF propagation in the Earth-ionosphere waveguide (EIWG). Ground propagation or mixed "sky" and ground propagation is avoided by requiring evidence of Earth-ionosphere waveguide dispersion. A further requirement is that the lightning strike must be inside the perimeter defined by the lightning sensor sites detecting the stroke. Under these conditions, the time and the location of the stroke can be determined, along with the rms errors. Lightning strokes with errors exceeding 30 Ps or To assist with identifying impulses from the same lightning stroke, the lightning sensor threshold is automatically adjusted to allow an average detection rate of three per second. This largely limits detection to the strongest 4% of all lightning strokes, of which about 40% meet the accuracy requirements for time and location

Dusty plasma effects in near earth space and interplanetary medium

We review dust and meteoroid fluxes and their dusty plasma effects in the interplanetary medium near Earth orbit and in the Earth’s ionosphere. Aside from in-situ measurements from sounding rockets and spacecraft, experimental data cover radar and optical observations of meteors. Dust plasma interactions in the interplanetary medium are observed by the detection of charged dust particles, by the detection of dust that is accelerated in the solar wind and by the detection of ions and neutrals that are released from the dust. These interactions are not well understood and lack quantitative description. There is still a huge discrepancy in the estimates of meteoroid mass deposition into the atmosphere. The radar meteor observations are of particular interest for determining this number. Dust measurements from spacecraft require a better understanding of the dust impact ionization process,as well as of the dust charging processes. The latter are also important for further studying nanodust trajectories in the solar wind. Moreover understanding of the complex dependencies that cause the variation of nanodust fluxes is still a challenge.540010117 Gästprofessur Mann540010110 Driftsmedel Pellinen-Wannber