Browse ORBilu by Open Access
- What it is and what it isn't
- Green Road / Gold Road?
- Ready to Publish. Now What?
- How can I support the OA movement?
- Where can I learn more?
ORBilu is a project developed by
  Study of space weather impact on Antarctica ionosphere from GNNS data; ; et al Poster (2016, April 29) The impact of solar activity on the ionosphere at polar latitudes is not well known compare to low and mid-latitudes due to lack of experimental observations, especially over Antarctica. Consequently, one ... [more ▼] The impact of solar activity on the ionosphere at polar latitudes is not well known compare to low and mid-latitudes due to lack of experimental observations, especially over Antarctica. Consequently, one of the present challenges of the Space Weather community is to better characterize (1) the climatological behavior of the polar ionosphere in response to variations of the solar activity and (2) the different response of the ionosphere at high latitudes during extreme solar events and geomagnetic storms. For that, the combination of GNSS measurements (e.g. GPS, GLONASS and Galileo) on two separate frequencies allows determining the ionospheric delay between a ground receiver and a satellite. This delay is function of the integrated number of electrons encountered in the ionosphere along the signal ray path, called the Total Electron Content (TEC). It is thus possible to study the behavior of ionospheric TEC at different time and spatial scales from the observations of a network of permanent GNSS stations. In the frame of GIANT-LISSA and IceCon projects we installed since 2009 five GNSS stations around the Princess Elisabeth station. We used these stations additionally to other stations from the IGS global network to estimate the ionospheric TEC at different locations over Antarctica. This study presents this regional data set during different solar activity levels and discusses the different climatological behaviors identified in the ionosphere at these high latitudes. Finally, we will show few examples of typical TEC disturbances observed during extreme solar events. [less ▲] Detailed reference viewed: 568 (23 UL)  Experiment to evaluate crustal motions across the Ardenne and the Roer Graben (north-western Europe) using absolute gravity measurements; ; Francis, Olivier  in Metrologia (2002), 39(5), 503-508 Absolute gravity measurements using the FG5-202 gravimeter have been conducted twice a year since September 1999 along a 120 km long profile across the Belgian Ardenne and the Roer Graben. As in this ... [more ▼] Absolute gravity measurements using the FG5-202 gravimeter have been conducted twice a year since September 1999 along a 120 km long profile across the Belgian Ardenne and the Roer Graben. As in this region there is a difference of an order of magnitude between the inferred vertical crustal movements deduced from the difference of levelling (about 1 mm/year) and geological information (0.1 mm/year), our goal is to better constrain the present-day deformation. The absolute gravity measurements are performed at Rochefort, Humain, Werpin, Manhay, Sprimont, Membach (Belgium) and Monschau, Julich and Bensberg (Germany). A complete description of the network is given, and specific difficulties at some stations are presented. The precision achieved, generally less than 2.0 Gal integrated over more than 24 h of observation, is quite satisfactory at all stations but Julich. The mining activities around Julich cause an increase in the noise up to 7 Gal integrated over more than 72 h. We also discuss possible causes of gravity variations in this region. At present, it is still not possible to detect any trend in the available data. However, after five years of observations, we should be able to detect or constrain any possible long-term trend with a limit of 2.5 mm/year, assuming that a height change of 1 mm causes a change in gravity of 0.2 Gal. To ensure that the absolute gravimeter is giving accurate results, it has been regularly compared with the superconducting gravimeter installed at the Membach reference station. [less ▲] Detailed reference viewed: 122 (3 UL)Comment on "Nature of the recent vertical ground movements inferred from high-precision leveling data in an intraplate setting: NE Ardenne, Belgium" by A. Demoulin and A. Collignon; ; et al in Journal of Geophysical Research (2002), 107(B11), 2281-2281 Comment on ‘‘Nature of the recent vertical ground movements inferred from high-precision leveling data in an intraplate setting: NE Ardenne, Belgium’’ by A. Demoulin and A. Collignon Detailed reference viewed: 184 (4 UL)Absolute gravity measurements in Belgium: a tool for geodynamic interpretation; Francis, Olivier ; in Degryse, Patrick; Sintubin, Manuel (Eds.) Contributions to the Geology of Belgium and Northwest Europe (2002) Detailed reference viewed: 82 (2 UL) |
||
