Atmospheric Sciences & Global Change Division
Correction Method for Infrared Detector Confirmed; Error in Clear Sky Bias Condition Remains Unresolved
To obtain accurate, high-spectral resolution ground-based observations of infrared radiation, the Department of Energy's Atmospheric Radiation Measurement (ARM) Program uses a sensor called an Atmospheric Emitted Radiance Interferometer (AERI). The AERI instrument uses a mercury cadmium telluride (MCT) detector, which provides excellent sensitivity to infrared radiance from 5-25 μm. The MCT detector, however, has a non-linear response, which means that its output is not linearly proportional in wavelength to the measured radiant energy. A set of experiments conducted by ARM researchers in November 2003 and January 2004 confirmed the accuracy of a nonlinearity correction for calibrating the MCT detector, and also ruled out this procedure as the source of error found in clear, dry conditions calculated by a line-by-line radiative transfer model (LBLRTM).