Proposal for a new generation OST-VC User Requirements Document P. Escudier and H. Bonekamp

Towards a new generation OST-VC Implementation of the OST-VC constellation is well underway Key role played by Copernicus sentinels complemented by other initiatives OST-VC fulfils the needs of large-scale and larger meso-scale monitoring Adequate to feed the current configuration of the Copernicus Marine Environment Monitoring Service as well as scientific uses. However new societal, science and operational uses are emerging A breakthrough improvement of the space and time resolution of the altimetry Virtual Constellation is required in a mid-term perspective Models will soon be ready to analyze and predict ocean at a much smaller scale  A new generation of constellation has to be defined CNES, ESA and other agencies have initiated preliminary analyses An encouragement from SIT Chair to EUMETSAT to support the development of this updated URD would be helpful

Current OST-VC roadmap Launch Date 15 16 17 18 19 20 21 22 23 24 25 27 13 14 26 Reference Nadir Missions (Non Sun-Synchronous) 20/08 Jason-2 FR/EU/USA Jason-CS-A/Sentine-6-A EU/USA JCS-B EU/USA Jason-3 FR/EU/USA Complementary Nadir Missions 02/13 Saral/AltiKa FR/Ind Sentinel-3A EU Sentinel-3B EU Sentinel-3C EU Sentinel-3D EU 04/10 CRYOSAT-2 EU 08/11 HY-2A CN HY-2C CN HY-2B CN HY-2D CN Broad-Coverage Mission SWOT USA/FR Compira jp Operating Development Proposed Feb 2016

Towards a new generation OST-VC Current OST-VC space/time overall resolution: ~100 km, 10 days Significant part of the ocean dynamics below 100 km It will be better characterized thanks to new technology : Higher along-track resolution on Sentinel-3 (delayed Doppler mode) Wide-swath altimetry on SWOT (NASA/CNES) and COMPIRA (JAXA) Comparison between drifting buoy trajectories and currents deduced from current OST-VC

Towards a new generation OST-VC Next steps Confirmation by CEOS SIT of the interest to move forward to a higher resolution Ocean Surface Topography monitoring system to support the future generation of operational oceanography and new science and applications objectives Analysis by various agencies of the different possible configurations: instrument technology, orbit configurations… Analysis of these configurations and coordination by OST- VC group Preliminary discussion at La Rochelle meeting Encouragement from SIT Chair to EUMETSAT to support the development of an updated URD that would document this new configuration