AIRS infrared polarization sensitivity and in-flight observations

The Atmospheric Infrared Sounder (AIRS) is a space-based instrument that measures the upwelling atmospheric spectrum in the infrared. AIRS is one of several instruments on the EOS-Aqua spacecraft launched on May 4, 2002. Typically, instrument polarization is not a concern in the infrared because the scene is usually not significantly polarized. A small amount of polarization is expected over ocean, which can be seen in the AIRS 3.7 mum window channels. The polarization is seen as a signal difference between two channels with the same center frequency but different polarizations. The observations are compared to a model that relies on measurements of instrument polarization made pre-flight. A first look at a comparison of the observations of sea surface polarization to expectations is presented.