Digital Array Gas Radiometer (DAGR)

The innovation proposed here is a digital array gas radiometer (DAGR), a new design for a gas filter correlation radiometer (GFCR) to accurately measure and monitor CO2, CO, CH4, N2O and other key trace gases in the boundary layer from space, aircraft or ground-based platforms. GFCR is a well-known and proven technology for trace gas detection and monitoring. However, its effectiveness in downlooking applications has been limited, primarily because variations in surface albedo degrade the performance. Our DAGR approach builds on traditional GFCR concepts and combines several new key elements: two-dimensional detector arrays, pupil imaging (imaging the aperture), and a novel calibration approach. With these enhancements and appropriate signal processing, the DAGR design overcomes the historical limitations of GFCR in downlooking applications. In addition, this design significantly boosts the sensitivity and expands the dynamic range traditionally available to these sensors. Finally, the innovation provides a calibration technique that nearly eliminates errors due to detector drift effects. The result will be a compact, static, robust system that can accurately measure important boundary layer species from a variety of platforms.