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An additional ionospheric layer, the F3 layer, has recently been identified in vertical incidence ionogram records from the equatorial station, Fortaleza in Brazil.

We describe a preliminary analysis of small-scale temperature perturbations in the stratosphere produced by long wavelength gravity waves, as measured globally during the CRISTA-SPAS missions. We focus on enhanced activity observed at the equator and near the southern tip of South America.

Recently, with the escalating cost of large satellite missions, attention has turned to smaller satellites. Their advantages of low overall cost in construction and launch, and short time span between conception and launch has given a new impetus to the further study of the geosphere.

A lot of measurements of the vertical geoelectric field have been carried out in the Russian Arctic and in Antarctica during the 1980’s. In this paper we briefly review the results of these measurements, supporting the concept of a global electric circuit.

The onset of auroral substorms is invariably associated with the generation of large-scale ionospheric disturbances (LSTID’s) which modify the virtual height (h’F) of the F-region, primarily at sub-auroral locations. Five sub-auroral ionosonde stations…

This paper presents the mathematical background of the derivation of atmospheric gravity-wave spectra from Rayleigh lidar observations of fractional density and/or temperature fluctuations.

Heard Island contains a system of lava tube caves in a largely pristine condition which are the best developed bedrock caves known in Antarctic or Subantarctic latitudes. They require special management because of significant and sometimes fragile attributes. Use for recreation…

In this paper we examine the geomagnetic signatures of solar wind impulses using magnetometer array data, a bistatic HF radar, and a co-located imaging riometer. The impulses were associated with 1.6mHz magnetic pulsations that were observed across a wide range of latitudes.

Sporadic E, abbreviated Es, is a very thin ionised layer and as its name suggests, it occurs sporadically at E region heights. To a radio wave Es often behaves as a smooth HF reflector. However, because of its complex structure and large spatial and temporal variability Es is a major problem…

This article aims to give a comprehensive view of the distribution patterns for natural and artificial radionuclides over Antarctica. We focus this study on 137Cs, 210Pb and tritium. Applying various statistical methods, we show that the deposition of radionuclides reveals a structured distribution…

In this paper we discuss a method for using the Global Positioning System (GPS) to monitor ionospheric irregularities in the high-latitude region. Dual-frequency GPS data, obtained from mid-latitude Australian and sub-Antarctic permanent GPS stations, are used to study various ionospheric features…

HF signals that propagate via the ionosphere may exhibit Doppler shifts due to a number of processes that give rise to a time dependent refractive index. This paper examines the role of ULF (1–100mHz) wave energy, incident from the magnetosphere, in causing Doppler shifts in HF signals.

The high altitude Dome C site offers excellent prospects for cosmic ray observations at low to moderate energies. A neutron monitor, based on the standard NM64 counter or on the new Helium counter technology could be an important addition to the worldwide monitor network.

A Ground Level Enhancement occurred on 14 July 2000 and was observed by at least 18 stations in the worldwide neutron monitor network. Earliest onset was observed between 10.30 and 10.35 UT at several stations. The event is associated with an X5.8 solar flare (importance 3B)…