Abstract: The GEOSCOPE observatory provides 37 years of continuous broadband data to the scientific community. The 33 operational GEOSCOPE stations are installed in 17 countries, across all continents and on islands throughout the oceans. They are equipped with three component very broadband seismometers (STS1, STS2 or T240) and 24 or 26 bit digitizers (Q330HR). Seismometers are installed with warpless base plates, which decrease long period noise on horizontal components by up to 15dB. All stations send data in real time to the IPGP data center and are automatically transmitted to other data centers (IRIS-DMC and RESIF) and tsunami warning centers. Recent instrumental improvements include the upgrades of the following stations: FUTU (Wallis and Futuna, South-Western Pacific Ocean), NOUC (New Caledonia, South-Western Pacific Ocean), FOMA (Madagascar, Indian Ocean) and AIS (Amsterdam Island, Indian Ocean). The recent replacement of the feedback electronics and the related cables at PAF (Kerguelen Island, Indian Ocean) has also fix a long period perturbation that was visible on the vertical component since a few years. Important upgrades are also underway at CCD (Concordia Station, Dome C, Antarctica) where a new post-hole installation is currently in preparation. A new site has been tested in Cameroon and a new station is planned there in 2019. New tools have been developed (Grafana and Influx DB) to monitor the state of health of all the stations. Data of the stations are technically validated by IPGP (27 stations) or EOST (6 stations) in order to check their continuity and integrity. A scientific data validation is also performed by analyzing seismic noise level of the continuous data and by comparing real and synthetic earthquake waveforms (body waves). After these validations, data are archived by the IPGP data center in Paris. They are made available to the international scientific community through different interfaces (see details on http://geoscope.ipgp.fr). All GEOSCOPE data are in miniseed format but using various conventions. An important technical work is done to homogenize the data miniseed formats of the whole GEOSCOPE database, in order to make easier the data duplication at the IRIS-DMC and RESIF data centers. The GEOSCOPE observatory also provides near-real time information on the World large seismicity (above magnitude 5.5-6) through the automated use of the SCARDEC method. Earthquake parameters (depth, moment magnitude, focal mechanism, source time function) are determined about 45 minutes after the occurrence of the event. A specific webpage is then generated, which also includes information for a non-seismologist audience (past seismicity, foreshocks and aftershocks, 3D representations of the fault motion…). This information is also disseminated in real-time through mailing lists and social networks. Examples for recent earthquakes can be seen in http://geoscope.ipgp.fr/index.php/en/data/earthquake-data/latest-earthquakes.

Abstract: Arctic snow cover dynamics offer a changing face in terms of temporal duration and water equivalent, due to recent climate change conditions (Callaghan et al., 2011; Lemke & Jacobi, 2012). Indeed, the Arctic is now experiencing some of the most rapid and severe climate change on earth. In this context, innovative and improved methods are helpful to enhance management of the snow-pack resource for climate research, hydrology and human activities. The characteristics of Arctic snow are different from “temperate” snow (i.e. the Alps), in terms of thickness, internal structure, thermal conductivity, and metamorphism. Ground observation often indicates wind slab at the snow surface, internal rounded grains, depth hoar at the bottom, and often internal ice layer or at the interface with ground surface (Dominé et al., 2016; Gallet et al., 2017, for spring snow). This work is part of the “Precip-A2” project (OSUG, Grenoble-France), focusing on snow and its interaction with the atmosphere, especially in terms of chemistry, radiative processes and precipitation. The application site is the Brøgger peninsula, focused on Ny-Ålesund area, Svalbard, Norway (N 78°55’ / E 11° 55’). One sub-task of the Precip-A2 project is dedicated to X-band radar measurements (ground and spaceborne) to retrieve physical properties of arctic snow.