SWOT Radiometer IGDR: Atmospheric Water and Sea Surface Brightness Temperatures

SWOT Level 2 Radiometer Brightness Temperatures and Troposphere Interim Geophysical Data Record (IGDR) Version 1.0 provides atmospheric water vapor, cloud liquid water, and wind speed derived from the Advanced Microwave Radiometer. This instrument measures sea surface brightness temperatures at 18.7, 23.8, and 34 GHz to correct for atmospheric delays in the SWOT mission's primary altimeter data. The interim dataset consists of discrete measurements along two tracks approximately 30 km from the satellite nadir, processed with preliminary orbit and calibration data.

Use Cases

• Correcting altimeter range delays for ocean topography based on estimated wet troposphere content.
• Analyzing atmospheric water vapor and cloud liquid water distribution based on multi-frequency brightness temperatures.
• Estimating sea surface wind speed coincident with nadir altimeter measurements.
• Studying atmospheric attenuation to radar backscatter for signal correction.

Strengths

• Data is from the joint NASA-CNES SWOT mission, which launched on December 16, 2022.
• Provides measurements at three specific microwave frequencies: 18.7, 23.8, and 34 GHz.
• Has a nominal latency of < 1.5 days, supporting near-real-time applications.
• Distributed in the standardized netCDF4 format, one file per half-orbit.

Limitations

• Metadata on row count, file size, and specific columns is unavailable across all sources.
• Data is an Interim Geophysical Data Record (IGDR) processed with preliminary calibrations and Medium-accuracy Orbit Ephemeris, indicating it is not the final product.
• The listed file formats (HTML, PDF, BIN, JPEG, ISO) appear generic and conflict with the described netCDF4 distribution.

Provenance

Source

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

Collection Method

Satellite measurements from the Advanced Microwave Radiometer (AMR), a Jason-class radiometer.

Time Range

Data collection began after the SWOT launch on December 16, 2022; specific end date is not provided.

Freshness

2026-04-09 21:51:13.371530

Geography

Global coverage over oceans, with measurements along two tracks approximately 30 km left and right of satellite nadir.