Advanced infrared sounding instruments for the next generation of polar orbiting satellites

Major improvements in atmospheric temperature and moisture sounding accuracy from new passive infrared sounders are expected in the early part of the next century. These new sounders are infrared Michelson interferometers and grating spectrometers with much higher spectral resolution and thousands of spectral measurements (channels) per scene. In contrast, today’s operational infrared sounder has only 19 channels, with much poorer spectral resolution. High spectral resolution, good signal to noise performance and many spectral measurements result in temperature and moisture sounding products with vertical resolution approaching 1 km. Overall accuracy in atmospheric temperature and moisture profiling (retrievals) is expected to be within 1 degree Kelvin and 10 % relative humidity, respectively, which represents a 50 % improvement over today’s performance. In combination with near global coverage, 2 - 4 times per day, advanced infrared sounding instruments are expected to yield large improvements in areas of numerical weather prediction, climate and nowcasting.

Three different advanced infrared sounding instruments are scheduled for launch in the next century. They include the Advanced InfraRed Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI) and the CRoss-track Infrared Sounder (CrIS). Each will be on different polar platforms. Description of the instruments, schedule and a comparison of sounding accuracy will be presented.