HIRDLS/Aura Level 3 Water Vapor Zonal Fourier Coefficients

The entire mission (~3 years) of HIRDLS satellite data is expressed as zonal Fourier coefficients in 1 degree latitude bands from -64 to 80 degrees at 121 pressure levels. Coefficients are computed from Level 2 profiles using a Kalman filter approach and are provided on a pressure grid with about 1 km vertical resolution. The data product is version 7 and was produced by the National Aeronautics and Space Administration.

Use Cases

• Model atmospheric water vapor distribution based on zonal Fourier coefficients
• Analyze longitudinal variability in water vapor using sine and cosine coefficients
• Study vertical profiles of water vapor across 121 pressure levels
• Compare daytime (ascending) and nighttime (descending) water vapor patterns

Strengths

• Data covers the entire mission (~3 years) of the HIRDLS instrument
• Provides coefficients for up to 7 sine and cosine waves for combined orbit node analysis
• Vertical resolution is about 1 km across 121 pressure levels
• Data is separated into ascending (daytime), descending (nighttime), and combined orbit nodes

Limitations

• Column-level documentation is absent; field semantics must be inferred after download
• Row count is unknown, which may limit suitability assessment
• The useful vertical range is limited to 200 to 10 hPa

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Coefficients computed from HIRDLS Level 2 profiles with a Kalman filter approach using both forward and backward passes in time.

Time Range

The entire mission (~3 years) of HIRDLS data.

Freshness

Last updated 2026-03-13 01:28:38.158948; freshness should be verified

Geography

Latitude bands from -64 to 80 degrees.