CoAuthors

Florence Birol (LEGOS/CTOH, France); Fabien Blarel (LEGOS/CTOH, France); Denis Blumstein (LEGOS/CNES, France); Frédéric Frappart (LEGOS/CTOH, France); Kévin Guerreiro (LEGOS/CTOH, France); Fabien Léger (LEGOS/CTOH, France); Rosemary Morrow (LEGOS/CTOH, France); Fernando Niño (LEGOS/CTOH, France)

The Center for Topography of the Oceans and Hydrosphere (CTOH) is a French Observation Service created in 1989 and dedicated to satellite altimetry studies. Its objectives are to 1) maintain and distribute homogeneous altimetric databases for ocean, hydrosphere and cryosphere applications, 2) help scientific users to develop new altimetry derived products and 3) contribute to the development and validation of new processing approaches of the altimetric data for emerging research domains (coastal ocean, oceanic sub-mesoscale phenomenons, continental surface water, sea ice, polar caps). The CTOH maintains homogeneous altimetric GDR data bases for the following missions : Topex/Poseidon, GFO, ENVISAT, Jason-1, Jason-2, Jason-3, Saral/Altika, Cryosat2 and Sentinel-3. Except for GFO, all these products are provided in netcdf format. A new version of ERS-2 data, reprocessed by the CTOH, including both ICE-1 and ICE-2 retrackers and all the usual corrections is also now available. Both 1Hz and 10/20/40Hz data are available globally (for oceans and continental surfaces). For some products, the CTOH database contains L1 products (waveforms). We also add about 20 recent altimetry corrections and auxiliary parameters in a homogeneous way to all GDRs. It includes tide models, DAC, MSS, geoids, and tropospheric corrections. New geophysical corrections are being developed for continental surfaces applications and distributed. In addition, the CTOH works on developing new altimetric products:
• Coastal products : X-TRACK along-track SLA time series and tidal harmonic constants, reprocessed with a software designed for coastal altimetry processing, cover now the global coastal ocean. A software dediceted to the inter-comparison between coastal altimetry data sets, model outputs and in-situ measurements is also under developments in order to help users with combined analysis including L3 altimetry products.
• Continental hydrology products : including the “Hydroweb” data base for monitoring river and lake levels. Hydroweb integrates the CASH project: Topex reprocessed data over terrestrial surface waters. Water level maps are also developed for 5 rivers: the Amazon, Orenoque, Gange-Bramhapoutre, Congo and Mekong.
• Sea-ice products : Monthly maps of the Arctic Sea Ice Thickness covering the period 2002-2017, from Envisat and CryoSat-2 measurements, is available. Snow depth monthly maps over sea ice are also available for the period 2013-2015 and is being extended up to 2017.
All these products are now progressively re-distributed via AVISO+, our new common platform with AVISO: http://www.aviso.altimetry.fr/en/home.html. More information can be found on the CTOH website http://ctoh.legos.obs-mip.fr/.