CHROMA O₂ A-band cloud retrieval

Knowledge graph centered on CHROMA O₂ A-band cloud retrieval with 15 nodes and 28 connections. Top connected: Gunnison, Ascension Island, Southern Great Plains, Atmospheric Radiation Measurement Program, Sierras de Córdoba.

Method synopsis

Bayesian retrieval algorithm using oxygen A-band absorption to simultaneously retrieve cloud top pressure, surface albedo, and cloud optical thickness from four near-infrared spectral channels. Uses Optimal Estimation technique with pre-calculated lookup tables.

Synthesized from method descriptions across 1 paper using this protocol.

Procedure from a recent peer-reviewed implementation

Steps below were extracted from the most recent peer-reviewed implementation of this protocol in the corpus — Evaluation of cloud height, optical thickness, and phase retrievals from the CHROMA algorithm applied to Sentinel-3 OLCI data (2025), Atmospheric Measurement Techniques. Implementations in other papers (listed below) may differ.

1. CHROMA algorithm application
   Applied CHROMA algorithm using four OLCI channels (OA12-OA15) with nominal central wavelengths of 753.75, 761.25, 764.375, and 767.50 nm and FWHM of 7.5, 2.5, 3.75, and 2.5 nm respectively. Used Bayesian retrieval approach with Optimal Estimation technique to simultaneously retrieve cloud top pressure, surface albedo, and cloud optical thickness. Algorithm runs twice per cloudy pixel with different cloud phase assumptions (liquid and ice) selecting solution with lower cost statistic.
   Quantities: 4 spectral channels near O₂ A-band, 2 retrievals per pixel (liquid and ice phase)Duration: Applied to all qualifying cloudy pixels over study periodConditions: Clear-sky pixels flagged as cloud or with retrieval cost >30 excluded from analysis
   Equipment: CHROMA algorithm, Pre-calculated lookup tables, Optimal Estimation framework

Typical Equipment

• CHROMA algorithm
• Pre-calculated lookup tables
• Optimal Estimation framework

Output Measurements

• cloud top pressure
• cloud top height
• surface albedo
• cloud optical thickness

Papers Using This Protocol (1)

Places Where Used