SWOT IGDR: Nadir Altimeter Sea Surface Measurements

SWOT Level 2 Nadir Altimeter Interim Geophysical Data Record Version 1.0 provides sea surface height, significant wave height, and wind speed measurements from the Poseidon-3C altimeter. The dataset consists of discrete measurements along the nadir track with sampling resolutions of approximately 6-km at 1Hz and 300-m at 20Hz. It is produced by the joint NASA-CNES SWOT mission, which launched on December 16, 2022, and data are 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 for climate and ocean circulation studies based on sea surface height measurements.
• Analyzing wave climate and marine safety based on significant wave height data.
• Assessing wind conditions over the ocean for meteorological models based on wind speed measurements.
• Near-real-time operational oceanography based on the dataset's nominal latency of < 1.5 days.
• Calibrating and validating hydrodynamic models based on high-resolution (300-m) along-track measurements.

Strengths

• Provides measurements from a dedicated, state-of-the-art satellite altimeter (Poseidon-3C) launched in December 2022.
• Offers dual sampling resolutions (approximately 6-km and 300-m) for flexible analysis scales.
• Has a defined processing standard (Medium-accuracy Orbit Ephemeris) and a structured delivery format (one netCDF-4 file per half orbit).

Limitations

• Metadata completeness is low: column names, exact size, row count, license, and author information are unknown across all sources.
• The dataset is labeled as 'Interim' and uses preliminary orbit and auxiliary data, indicating it is not the final, calibrated product.
• The spatial coverage is limited to measurements along the satellite's nadir track, not a full global grid.

Provenance

Source

Surface Water and Ocean Topography (SWOT) mission, a joint project between NASA and CNES.

Collection Method

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

Time Range

Data collection began after the mission launch on December 16, 2022.

Freshness

2026-04-10 19:43:55.950300

Geography

Global, along the satellite's nadir track over oceans and inland water bodies.