SWOT L2 NALT IGDR: Interim Geophysical Data Record for Ocean Surface

Data from the SWOT mission launched on December 16, 2022, provides interim geophysical measurements of sea surface height, significant wave height, and wind speed from the Poseidon-3C nadir altimeter. The dataset consists of discrete measurements along the satellite's nadir track with sampling resolutions of approximately 6-km at 1Hz and 300-m at 20Hz, processed using preliminary orbit and auxiliary data. It is distributed as one netCDF-4 file per half-orbit with a nominal latency of less than 1.5 days.

Use Cases

• Monitoring ocean surface topography and dynamic height anomalies based on sea surface height measurements.
• Analyzing wave climate and forecasting based on significant wave height data.
• Studying air-sea interactions and wind-driven processes using wind speed measurements.
• Validating and calibrating ocean circulation models with preliminary, low-latency satellite data.

Strengths

• Provides data with high spatial resolution, offering measurements at approximately 300-meter intervals.
• Features low latency, with data available less than 1.5 days after acquisition.
• Is a product of a major joint NASA-CNES satellite mission, indicating institutional backing.

Limitations

• Uses preliminary orbit ephemeris and auxiliary data, which likely reduces accuracy compared to final products.
• Metadata on specific columns, row counts, and file sizes is not provided across all sources.
• The license is ambiguously listed as 'other-license-specified' without explicit details.

Provenance

Source

NASA and CNES (Surface Water and Ocean Topography mission).

Collection Method

Satellite remote sensing via the Poseidon-3C nadir altimeter.

Time Range

Post-launch from December 16, 2022 onward.

Freshness

Last updated on 2026-04-09 according to datagov.

Geography

Global coverage along the satellite's nadir ground track.