HIRDLS/Aura HNO3 Zonal Fourier Coefficients for 3-Year Mission

HIRDLS/Aura Level 3 Nitric Acid (HNO3) Zonal Fourier Coefficients version 7 contains the entire mission (~3 years) of satellite data expressed as Fourier coefficients in 1-degree latitude bands. The coefficients are computed from Level 2 profiles using a Kalman filter and are provided on a pressure grid with about 1 km vertical resolution. The data are stored in HDF-EOS5 format by NASA.

Use Cases

• Reconstruct nitric acid concentrations at any longitude based on the Fourier coefficients.
• Analyze vertical distribution of HNO3 across 121 pressure levels from 215 to 5.1 hPa.
• Compare daytime (ascending) and nighttime (descending) atmospheric chemistry profiles.
• Study long-term (~3 year) trends in nitric acid using the combined mission data.

Strengths

• Provides data for the entire ~3-year mission period.
• Offers vertical resolution of about 1 km across 121 pressure levels.
• Includes separate data fields for ascending (daytime) and descending (nighttime) orbit nodes.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• Geographic coverage is limited to latitude bands from -64 to 80 degrees.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Coefficients computed from HIRDLS Level 2 profiles with a Kalman filter approach.

Time Range

The entire mission (~3 years)

Freshness

Last updated 2026-03-13 01:28:46.968736; freshness should be verified.

Geography

Latitude bands from -64 to 80 degrees