Abstract.During the total solar eclipse observed in Europe on August 11, 1999, measurements were made of the amplitude and phase of four VLF transmitters in the frequency range 16-24 kHz. Five receiver sites wcrc set up, and significant variations in phase and amplitude are reported for 17 paths, more than any previously during an eclipse. Distances from transmitter to receiver ranged from 90 to 14,510 kin, although the majority were <2000 kin. Typically, positive amplitude changes were observed throughout the whole eclipse period on path lengths <2000 kin, while negative amplitude changes were observed on paths >10,000 kin. Negative phase changes were observed on most paths, independent of path length. Although there was significant variation from path to path, the typical changes observed were N3 dB and -

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[1] A new, unique system has been developed for the automatic detection and analysis of whistlers. The Automatic Whistler Detector and Analyzer (AWDA) system has two purposes: (1) to automatically provide plasmaspheric electron densities extracted from whistlers and (2) to collect statistical data for the investigation of whistler generation and propagation. This paper presents the details of and the first results obtained by the automatic detector segment. The detector algorithm is based on image correlation where the target image is a preprocessed spectrogram of raw VLF signals and the pattern is a model whistler. The first AWDA system has been working in Tihany, Hungary (L = 1.8), and has collected 100,000 whistler traces per year. The overall detection efficiency using a parameter set optimized for purpose 2 is 90% for misdetection and 50-80% for false detection. The statistical analysis over the period February 2002 to February 2008 including 600,000 whistler traces shows high diurnal variations; whistler were mainly, but not only, detected when both the source and receiver regions were unlit. The seasonal occurrence is high during austral summer and low during austral winter. Comparison with Tarcsai et al. 's (1988) statistical study on Tihany whistlers shows differences in both diurnal and seasonal variations, but the latter study was made on 1388 manually identified whistlers only. The L value distributions of both data sets are similar. A global network of AWDA systems (AWDAnet) has been set up to overcome the time and space limitations of a single station; the network consists of 13 nodes, and another 6 are envisaged for the near future.

[1] The Antarctic-Arctic Radiation-belt (Dynamic) Deposition-VLF Atmospheric Research Konsortium (AARDDVARK) provides a network of continuous long-range observations of the lower ionosphere in the polar regions. Our ultimate aim is to develop the network of sensors to detect changes in ionization levels from $30--90 km altitude, globally, continuously, and with high time resolution, with the goal of increasing the understanding of energy coupling between the Earth's atmosphere, the Sun, and space. This science area impacts our knowledge of space weather processes, global atmospheric change, communications, and navigation. The joint New Zealand-United Kingdom AARDDVARK is a new extension of a well-established experimental technique, allowing long-range probing of ionization changes at comparatively low altitudes. Most other instruments which can probe the same altitudes are limited to essentially overhead measurements. At this stage AARDDVARK is essentially unique, as similar systems are only deployed at a regional level. The AARDDVARK network has contributed to the scientific understanding of a growing list of space weather science topics including solar proton events, the descent of NO x into the middle atmosphere, substorms, precipitation of energetic electrons by plasmaspheric hiss and electromagnetic ion cyclotron waves, the impact of coronal mass ejections upon the radiation belts, and relativistic electron microbursts. Future additions to the receiver network will increase the science potential and provide global coverage of space weather event signatures.

The results of the first 18 months of the PLASMON project are presented. We have extended our three, existing ground-based measuring networks, AWDANet (VLF/whistlers), EMMA/SANSA (ULF/FLRs), and AARDDVARK (VLF/perturbations on transmitters' signal), by three, eight, and four new stations, respectively. The extended networks will allow us to achieve the four major scientific goals, the automatic retrieval of equatorial electron densities and density profiles of the plasmasphere by whistler inversion, the retrieval of equatorial plasma mass densities by EMMA and SANSA from FLRs, developing a new, data assimilative model of plasmasphere and validating the model predictions through comparison of modeled REP losses with measured data by AARDDVARK network. The first results on each of the four objectives are presented through a case study on a space weather event, a dual storm sudden commencement which occurred on August 3 and 4, 2010.