Bjarke Nilsson (DTU Space, Denmark); Jon Kirby (DTU Space, Denmark); Farshad Salajeghed (University of Newcastle, NSW, Australia); Benjamin J Phrampus (United States Naval Research Laboratory, Stennis Space Center, USA); Paul Elmore (Applied Physics Laboratory, Johns Hopkins University, USA); James Beale (National Geospatial-Intelligence Agency, St Louis, , USA); Roberts Jamie (National Geospatial-Intelligence Agency, St Louis, , USA); Luis Parez (The University of Southern Mississippi, USA); Yao Yu (Scripps Institution of Oceanography, University of California San Diego, USA); David Sandwell (Scripps Institution of Oceanography, University of California San Diego, USA); Walter Smith (Center for Satellite Applications and Research, National Oceanographic and Atmospheric Administration, USA)

The Surface Water and Ocean Topography (SWOT) satellite mission is currently providing sea surface height observations with unprecedented detail. The marine gravity field, the mean sea surface (MSS), and gravity-derived bathymetry are being improved by SWOT in ways that are truly phenomenal and revolutionary. However, these improvements are non-uniformly distributed over the oceans due to two factors: (1) SWOT's 21-day orbit leaves diamond-shaped gaps in the coverage of the oceans, and (2) SWOT has optimal sampling resolution close to the center of each swath, with higher noise moving closer to the edges. This limits the area covered by the highest possible resolution obtained from SWOT These two limitations have left a clear visible impact on the MSS and gravity with non-uniform accuracy and resolution. If SWOT continues on the same 21-day repeat orbit, further improvements in the MSS & gravity will be marginal at best.
Shifting the orbit of SWOT to a new ground track that interlaces the current orbit will provide high-resolution SWOT in all diamond-shaped holes (in the present field) and will result in major gains in accuracy and resolution of the resulting MSS, gravity and derived bathymetry. More important is that these will all have uniform accuracy and resolution globally.
Shifting the ground-track to an interlaced orbit will have the largest effect at low latitudes where the diamonds are largest (up to >100 km in the north-south direction). At mid and high latitudes, where the diamond decreases in size the effect is smaller until


Spatial resolution determined from spectral coherence between the new mean sea surface model (DTU25) that contains SWOT data. Current state of the art models (DTU21, CLS22 and Hybrid MSS) as well as 93 cycles of an independent SWOT pass from the Calibration and Validation (CalVal) orbit configuration.
Using data from the selected CalVal orbit, which is shifted compared with the Science orbit, we can determine the difference between along-track segments that are affected by diamond gaps, and along-track segments that are not affected by diamond gaps in the Science orbit.