The Cross-track Infrared Sounder (CrIS) and the Advanced Microwave Technology Sounder (ATMS) is a suite of critical instruments (CrIMSS) under development for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) program. CrIS is an interferometric sounding sensor which measures upwelling earth radiation at very high spectral resolution and uses this data combined with data from ATMS; which is a 22 channel passive microwave radiometer to construct vertical profiles of atmospheric temperature and moisture. This purpose of this paper is to focus on the instrument development status of the CrIMSS for a flight of opportunity on the NPOESS Preparatory Project (NPP) in late 2005.

As part of a suite of operational instruments to be launched In the 2009 timeframe, the Cross-track Infrared Sounder (CrIS) is a Fourier Transform Spectrometer (FTS) currently being developed for the U.S Government by ITT Aerospace. The ATMS currently being developed by Aerojet under a NASA contract draws its heritage directly from AMSU-A/B, but with reduced volume, mass, and power. The CrIS combined with data from the ATMS will provide real time radiometric data and a suite of products supporting Numerical Weather Forecasting (NWP) centers around the world. The heart of the CrIS sensor is a Michelson interferometric sounder capable of sensing upwelling infrared radiances from 3 to 16 mm. The ATMS has Temperature and moisture sounding capability in the 23/31, 50, 89,150, and 183 GHz spectral range

The performance of the CrIMSS sensor suite is a considerable leap forward when compared to existing operational sounders due to much improved spectral resolution and many more channels. High spectral resolution also allows the selection of temperature sounding channels that are not contaminated by water vapor lines or by emissions from other active gases and provides spectrally clean window-channels for surface measurements. The noise equivalent radiance and noise equivalent temperature achieved in the key LW and MW bands are fairly low. Radiometric uncertainty levels are also quite good. The CrIS design combined with data from the ATMS is expected to yield temperature uncertainty of less than 1.0 K per 1 km layers and water vapor uncertainty of less than 15 % per 2 km layers in the troposphere.