Impact of the 26-30 May 2003 solar events on the earth ionosphere and thermosphere.

During the last week of May 2003, the solar active region AR 10365 produced a large number of flares, several of which were accompanied by Coronal Mass Ejections (CME). Specifically on 27 and 28 May three halo CMEs were observed which had a significant impact on geospace. On 29 May, upon their arrival at the L1 point, in front of the Earth's magnetosphere, two interplanetary shocks and two additional solar wind pressure pulses were recorded by the ACE spacecraft. The interplanetary magnetic field data showed the clear signature of a magnetic cloud passing ACE. In the wake of the successive increases in solar wind pressure, the magnetosphere became strongly compressed and the sub-solar magnetopause moved inside five Earth radii. At low altitudes the increased energy input to the magnetosphere was responsible for a substantial enhancement of Region-1 field-aligned currents. The ionospheric Hall currents also intensified and the entire high-latitude current system moved equatorward by about 10°. Several substorms occurred during this period, some of them - but not all - apparently triggered by the solar wind pressure pulses. The storm's most notable consequences on geospace, including space weather effects, were (1) the expansion of the auroral oval, and aurorae seen at mid latitudes, (2) the significant modification of the total electron content in the sunlight high-latitude ionosphere, (3) the perturbation of radio-wave propagation manifested by HF blackouts and increased GPS signal scintillation, and (4) the heating of the thermosphere, causing increased satellite drag. We discuss the reasons why the May 2003 storm is less intense than the October-November 2003 storms, although several indicators reach similar intensities

Accélérateur de deutérons à très basse tension

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Geocenter motion measured by DORIS and SLR and geophysical expectations

Journal of Geodesy, v. 80, n. 8-11, p. 637-648, 2006. http://dx.doi.org/10.1007/s00190-006-0079-zInternational audienc

Recherche-action dans un processus de planification territoriale participative. Le SCOT de Thau (France)

Regional and urban planning in France tends to be more distributed due to the decentralisation process but also more integrated and more participative. This is the case for coastal areas where a new type of integrated planning approach start to be experimented on several test areas, including the Thau territory. This area is subject to high pressures which generate numerous conflicts. To cope with these issues, new urban and water planning documents based on a sustainable development project are currently elaborated in a participatory way. Our research teams are supporting the leading institution to organise and evaluate the participatory process. In this paper, the context of the Thau territory is presented after a brief overview of spatial planning in France. Then, emphasis is put on the participatory process itself as well as on tools and methods that are used to support it. Yet the evaluation of this process is discussed

Analysis of scintillation recorded during the PRIS measurement campaign

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Ionospheric effects on GNSS performance

International audienceThis paper presents the features of the MONITOR project. This project initiated by ESA / ESTEC aims to increase the knowledge of the ionospheric effects and its impact on GNSS systems during active periods of solar activity. It includes the deployment of a set of GNSS-based ionospheric monitoring receivers worldwide distributed, the development of specific analysis software tools some of them integrated on a common platform, others distributed providing products routinely and a measurement campaign which will last beyond the peak of the current solar cycle