On the spatial resolution of the future SWOT SSH measurements
Abstract
The Surface Water and Ocean Topography (SWOT) mission aims to measure the sea surface height (SSH) at a high spatial resolution using Ka-band Radar Interferometer (KaRIn). The primary oceanographic objective is to characterize the ocean eddies at a spatial resolution of 15 km for 68% of the ocean. This resolution is derived from the ratio between the wavenumber spectrum of the conventional altimeter (projected to submesoscale) and the SWOT SSH errors. While the 15 km threshold is useful as a global approximation of the spatial scales resolved by SWOT (SWOT-scale), it can be misleading for regional studies. Here we revisit the problem using a high-resolution ( 2km) tide-resolving global ocean simulation and map the SWOT-scale as a function of latitude-longitude and season. The results show that the SWOT-scale has a geographic and seasonal dependence. It increases from about 15 km in low latitudes to 30-45 km in mid- and high-latitudes and peaks generally in late winter and early spring but with a large geographic variation. Both eddies and internal gravity waves/tides have a significant contribution to the scale variation. These analyses provide a guideline for interpreting the anticipated observations from SWOT and shed light on the development of the methodologies for analyzing the future SWOT data.
The Surface Water and Ocean Topography (SWOT) mission aims to measure the sea surface height (SSH) at a high spatial resolution using Ka-band Radar Interferometer (KaRIn). The primary oceanographic objective is to characterize the ocean eddies at a spatial resolution of 15 km for 68% of the ocean. This resolution is derived from the ratio between the wavenumber spectrum of the conventional altimeter (projected to submesoscale) and the SWOT SSH errors. While the 15 km threshold is useful as a global approximation of the spatial scales resolved by SWOT (SWOT-scale), it can be misleading for regional studies. Here we revisit the problem using a high-resolution ( 2km) tide-resolving global ocean simulation and map the SWOT-scale as a function of latitude-longitude and season. The results show that the SWOT-scale has a geographic and seasonal dependence. It increases from about 15 km in low latitudes to 30-45 km in mid- and high-latitudes and peaks generally in late winter and early spring but with a large geographic variation. Both eddies and internal gravity waves/tides have a significant contribution to the scale variation. These analyses provide a guideline for interpreting the anticipated observations from SWOT and shed light on the development of the methodologies for analyzing the future SWOT data.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS52B..02W
- Keywords:
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- 1845 Limnology;
- HYDROLOGYDE: 1856 River channels;
- HYDROLOGYDE: 4520 Eddies and mesoscale processes;
- OCEANOGRAPHY: PHYSICALDE: 4544 Internal and inertial waves;
- OCEANOGRAPHY: PHYSICAL