DFG Roundtable workshop Surface Water and Ocean Topography (SWOT)

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DFG Roundtable Surface Water and Ocean Topography (SWOT), Feb. 7 and 8 2019, Bonn, Germany.

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 https://uni-bonn.sciebo.de/s/rizbGs2MULs6qgI

Roundtable Summary

About forty scientists from oceanography, hydrology, cryosphere research, geodesy and remote sensing met at the University of Bonn’s Institute of Geodesy and Geoinformation on February 7 and 8, 2019, to discuss potential applications of the SWOT (Surface Water and Ocean Topography) satellite mission, which will be launched by NASA and CNES in late 2021. The workshop was organized by Luciana Fenoglio and Jürgen Kusche from the Astronomical, Physical and Mathematical (APMG) group at IGG and was funded by DFG.
The SWOT mission, scheduled for launch in September 2021, will observe the whole continental waters-estuaries-ocean continuum and thus link the ocean and hydrology scientific communities. SWOT will provide global, high-resolution observations in coastal regions with its new capability of mapping sea surface height down to 15 km scales, which will improve the knowledge of coastal ocean dynamics, coastal and internal tides, currents and storm surges. On inland waters, SWOT will measure water elevation, water mask and water slope, which are key measurements for the derivation of the streamflow and discharge.
The workshop began with invited presentations from the SWOT ocean and hydrology science leads L.L. Fu (NASA/JPL) and J.-F. Cretaux (CNES), addressing programmatic issues, mission science objectives, instrument performance and  research questions and anticipated improvements in ocean science and terrestrial hydrology. Followed contributions from the participants on the first day on oceanographic (9 presentations) and on the second day on hydrological and ice (8 presentations) applications. Main themes of the workshop were:

• planned cal/val activities, in particular with respect to the 1-day calibration orbit over Germany.
• ideas for ocean application, benefits of the high-resolution mapping of sea surface e.g. for eddy research
• ideas for land hydrology applications, e.g.  for lake and wetlands research, for water resource assessments, and for river discharge mapping
• suggestions for other applications such as ice topography, discussion on data products,
• and exploring funding opportunities at a national level.
  All participants acknowledged the productive framework of the workshop, expressed their high interest in continuing the discussion and better coordinating efforts in Germany. It was agreed to form a core group that would develop a strategic agenda, aligned with the official SWOT project, coordinate potential german research contributions. Questionnaire and interest in further meeting and activities for the new build group was distributed.
  
  
  Here are some details about the SWOT Mission:
  
  SWOT will map two parallel 50-km-wide swaths, with a data gap at nadir of 20 km every 21 days during the scientific phase of the mission. Within this repeat period, 2-3 revisits can be expected at our latitudes, 1-2 revisits at lower and more at higher latitudes. During the calibration/validation phase of three months it will map a 1000 long stripe over Germany every day. Figure 1 shows the principle of observations. Figure 2 shows the SWOT nadir ground-tracks over Central Europe in the 1-day phase.

Fig. 1 SWOT swaths: Karin interferometer will produce two parallel tracks, with a Nadir track from a traditional altimeter in the gap between the swaths. The overall width of the swaths will be approximately 120 km (Credit: Yeosang Yoon with images from NASA).

Fig. 2. SWOT ground-track of the 1-day phase with  in-situ tide gauge (triangle), GPS (circle), wave measurement (square) and Sentinel-3A ground track (-- line).  German Combined QuasiGeoid 2016 (GCG2016) in color map.