Thermodynamic product retrieval methodology and validation for NAST-I

Area of Science:

• Atmospheric remote sensing
• Environmental monitoring
• Satellite instrumentation

Background:

• The National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed (NAST) utilizes airborne instruments for atmospheric research.
• NAST comprises two passive, cross-track scanning instruments: NAST-I (infrared interferometer) and NAST-M (microwave radiometer).
• NAST-I operates at high altitudes (approx. 20 km) on aircraft like the NASA ER-2, offering high spectral resolution (0.25 cm⁻¹) and moderate spatial resolution.

Purpose of the Study:

• To detail the methodology for retrieving atmospheric temperature and composition profiles using NAST-I radiance spectra.
• To validate the accuracy of spectral radiance measurements, retrieval algorithms, and scanning capabilities through field campaigns.
• To demonstrate the instrument's capability in identifying fine-scale atmospheric features.

Main Methods:

• Retrieval of atmospheric profiles using a statistical eigenvector regression algorithm.
• Improvement of profile retrievals with a nonlinear physical retrieval algorithm when necessary.
• Validation using data from multiple field campaigns under diverse meteorological conditions.

Main Results:

• Successful retrieval of atmospheric temperature and composition profiles from NAST-I data.
• Verification of the accuracy of spectral radiance, retrieval algorithms, and scanning capabilities.
• Demonstration of the ability to resolve fine-scale horizontal atmospheric features with high vertical resolution.

Conclusions:

• The NAST-I instrument and its retrieval methodology are effective for atmospheric profiling.
• The system demonstrates potential for detailed atmospheric observation and environmental monitoring.
• The validated methodology supports the development of advanced satellite-based atmospheric sounders.