Sentinel-6A MF: High-Resolution Ocean Surface Topography from Altimetry

NASA's Sentinel-6A Michael Freilich spacecraft provides reprocessed Level 2 high-resolution non-time-critical altimetry data from its Poseidon-4 SAR instrument. This dataset contains sea surface height, sea surface height anomalies, and significant wave height, along with 1 Hz and 20 Hz Ku-band measurements and corrections from the AMR-C instrument. The product is analogous to the Jason-3 GDR standard and is available in both a standard release with 1 Hz and 20 Hz data and a reduced release with only 1 Hz observations.

Use Cases

• Monitoring global and regional sea level rise based on Sea Surface Height Anomaly (SSHA) measurements.
• Analyzing ocean wave climate and energy using Significant Wave Height (SWH) data.
• Studying mesoscale ocean dynamics like eddies and currents from high-resolution 20 Hz sea surface topography.
• Validating and calibrating ocean models with precise, reprocessed non-time-critical altimetry data.
• Assimilating corrected range, orbital altitude, and atmospheric data for precise geophysical parameter retrieval.

Strengths

• Provides high-resolution (HR) data at both 1 Hz and 20 Hz sampling rates, enabling detailed analysis of ocean features.
• Includes reprocessed, non-time-critical (NTC) data with a 60-day latency, suggesting higher accuracy and stability for climate studies.
• Contains a comprehensive suite of geophysical parameters and corrections (SSH, SSHA, SWH, wind-speed) from the primary P4 altimeter and the AMR-C instrument.
• Cross-platform presence on Data.gov and NASA EarthData indicates institutional endorsement and reliability for the user community.

Limitations

• Critical metadata is missing: no row counts, file sizes, or specific column names are provided across any source.
• Sources describe two distinct product versions (standard with 20 Hz, and reduced without 20 Hz) without clear differentiation in the provided metadata, creating potential user confusion.
• The 'last updated' field shows a future date (2026-04-09), which is inconsistent and suggests metadata maintenance issues.

Provenance

Source

National Aeronautics and Space Administration (NASA)

Collection Method

Reprocessed Level 2 data from the Poseidon-4 Synthetic Aperture Radar (SAR) altimeter on the Sentinel-6A Michael Freilich spacecraft.

Time Range

null

Freshness

2026-04 09 22:22:04.348960 (Note: This is a future date, indicating a potential metadata error.)

Geography

Global ocean coverage from the satellite's orbit.