Cross-track Infrared Sounder

Cross-track Infrared Sounder
Name	Cross-track Infrared Sounder
Operator	National Aeronautics and Space Administration; National Oceanic and Atmospheric Administration
Country	United States
Spacecraft	Suomi NPP; NOAA-20; MetOp (planned partnerships)
Type	Sounder
Wavelength	Infrared
Spectral bands	Multispectral
Launched	2011; 2017
Status	Operational

Cross-track Infrared Sounder The Cross-track Infrared Sounder is a satellite-borne hyperspectral infrared radiometer designed to measure atmospheric temperature and moisture profiles, surface properties, and trace gases. Developed through collaborations between National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, and industrial partners such as Ball Aerospace and Raytheon, it complements instruments like the Advanced Microwave Sounding Unit and the Atmospheric Infrared Sounder on missions including Suomi NPP and NOAA-20. The instrument contributes to global numerical weather prediction centers such as the European Centre for Medium-Range Weather Forecasts, the National Centers for Environmental Prediction, and the UK Met Office.

Overview

The instrument performs cross-track scanning to provide global coverage, producing radiance spectra used by assimilation systems at institutions like ECMWF, NCEP, and Met Office. It builds on heritage from missions such as TIROS and NOAA series and complements spaceborne assets like Aqua (satellite), Terra (satellite), and GOES-R. Design motivations included improving forecasts for events studied by World Meteorological Organization programs and operational centers such as European Organisation for the Exploitation of Meteorological Satellites.

Design and Instrumentation

The sensor employs cryogenically-cooled detectors and a grating spectrometer architecture derived from technologies used on AIRS and IASI. Key components were produced by contractors including Ball Aerospace, Raytheon, and research laboratories such as Jet Propulsion Laboratory and NASA Goddard Space Flight Center. The cross-track scanner provides swath widths comparable to IASI and angular sampling strategies akin to instruments on MetOp platforms. Spectral calibration and optical benches trace lineage to instruments developed for programs at Caltech, MIT, and University of Wisconsin–Madison. Onboard subsystems interface with spacecraft buses built by Ball Aerospace and supported by mission operations centers at NOAA Satellite Operations Facility.

Calibration and Data Processing

Radiometric calibration uses onboard blackbody references and cold space views, techniques refined by teams at NASA Langley Research Center, NOAA's National Environmental Satellite, Data, and Information Service, and European Space Agency laboratories. Level 0 to Level 2 processing chains were developed with contributions from Science Applications International Corporation and academics at Colorado State University and University of Wisconsin–Madison. Data assimilation routines link to models from NOAA Global Forecast System, ECMWF Integrated Forecasting System, and research codes from National Center for Atmospheric Research and University Corporation for Atmospheric Research. Validation campaigns involved instruments from NOAA PSL, ARM Climate Research Facility, and airborne platforms operated by NASA Armstrong Flight Research Center.

Applications and Uses

Outputs support operational forecasting at NCEP, climate monitoring by NOAA Climate Program Office, and research at institutions such as Scripps Institution of Oceanography, Columbia University, and Princeton University. Uses include retrievals of temperature and humidity profiles for assimilation into GFS and IFS, detection of volcanic ash impacting aviation stakeholders like Federal Aviation Administration, and monitoring of greenhouse gases alongside missions like OCO-2 and GOSAT. Environmental applications extend to ocean surface temperature estimation used by NOAA Fisheries, studies of polar processes relevant to National Snow and Ice Data Center, and wildfire smoke tracking benefiting agencies such as Environmental Protection Agency.

Mission History and Deployment

First flown on Suomi NPP in 2011 and subsequently on NOAA-20 in 2017, the instrument continued a lineage from earlier sounding programs including HIRS and AIRS. International coordination involved agencies such as European Space Agency and operational centers like EUMETSAT for cross-calibration with IASI on MetOp. Development milestones were overseen by program offices at NASA Headquarters and NOAA Office of Satellite and Product Operations, with launch services contracted through providers including United Launch Alliance for the carriers that placed NOAA-20 into orbit.

Performance and Validation

Validation campaigns compared profiles against radiosonde networks coordinated by World Meteorological Organization and research sites such as ARM Southern Great Plains and Barrow Observatory. Performance assessments published by teams at NASA Goddard, NOAA NESDIS, and JCSDA demonstrated improvements in short-term forecast skill at centers including ECMWF and NCEP. Cross-calibration efforts leveraged instruments like Aqua AIRS, MetOp IASI, and microwave sounders from GCOM-W to quantify biases for assimilation into operational systems including Global Data Assimilation System.

Category:Earth observation instruments