MODIS Aqua Satellite Total Precipitable Water Vapor Swath Data

MODIS/Aqua satellite data provides total atmospheric column water vapor amounts over clear land, ocean, and above clouds. The level-2 product contains 13 gridded parameters, including water vapor estimates at 1km and 5km resolutions, stored in HDF-EOS files. It is produced by the NASA MODIS Science Team using near-infrared and infrared retrieval algorithms.

Use Cases

• Modeling the hydrological cycle using global near-infrared and infrared estimated water vapor columns.
• Analyzing aerosol-cloud interactions by correlating water vapor correction factors with cloud mask data.
• Studying diurnal water vapor patterns by combining daytime-only near-infrared estimates with day/night infrared estimates and scan start time.
• Assessing retrieval quality for specific regions using the QA flags for near-infrared and infrared retrieval.
• Investigating surface reflectance impacts on water vapor sensitivity using solar zenith angle and sensor viewing geometry parameters.

Strengths

• Provides dual-resolution data with water vapor parameters at 1km (near-infrared) and 5km (infrared) pixel resolution.
• Contains 13 distinct gridded Scientific Data Sets (SDS) per file, including geolocation, viewing geometry, and quality assurance.
• Offers global spatial coverage over clear land, extended clear ocean, and above clouds.

Limitations

• Near-infrared water vapor estimates are limited to daytime measurements with a solar zenith angle less than 72 degrees.
• The near-infrared algorithm refinement is no longer supported by NASA, potentially limiting future methodological updates.
• Data volume is approximately 1 GB per day, which may require significant storage and processing capacity.

Provenance

Source

NASA MODIS Science Team via the MODIS-Atmosphere site.

Collection Method

Satellite remote sensing from the MODIS/Aqua instrument using near-infrared and infrared retrieval algorithms.

Time Range

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Freshness

Near Real Time (NRT)

Geography

Global coverage over land and ocean.