CrIS

CrIS
Name	CrIS
Type	scanning infrared sounder
Operator	National Oceanic and Atmospheric Administration / National Aeronautics and Space Administration
Mission	Suomi NPP / JPSS
Launch	2011 / 2017
Wavelength	3.9–15.4 μm
Spectral resolution	~0.625 cm−1

CrIS CrIS is a spaceborne hyperspectral infrared sounder developed to provide high‑spectral‑resolution radiance measurements for atmospheric sounding and climate monitoring. It operates on polar‑orbiting platforms to deliver temperature and moisture profiles, trace gas retrievals, and radiometric benchmarks that support weather forecasting and climate research. CrIS complements microwave sounders and visible imagers to enhance numerical weather prediction and long‑term atmospheric composition datasets.

Overview

The instrument is flown on Suomi NPP and NOAA-20 (part of the Joint Polar Satellite System), contributing to operational and research streams coordinated by NOAA and NASA. CrIS provides radiance spectra across shortwave, midwave, and longwave infrared bands, enabling retrievals related to tropospheric temperature, humidity, and constituents such as carbon dioxide, methane, ozone, and nitrous oxide. Data from CrIS are assimilated into models run at centers including the European Centre for Medium-Range Weather Forecasts, the National Centers for Environmental Prediction, and the Met Office to improve forecasts and reanalysis products like ERA5. The instrument supports international collaborations with agencies such as EUMETSAT, the Japan Meteorological Agency, and the Canadian Space Agency.

Instrument Design and Specifications

CrIS is a Fourier transform spectrometer built with heritage from airborne and satellite instruments including ATMOS, TES, and the AIRS program; it uses a Michelson interferometer architecture and a common aperture cryogenic focal plane. The design incorporates a scan mirror synchronized with the Visible Infrared Imaging Radiometer Suite on the same spacecraft to provide collocated nadir and swath sampling, enabling synergy with imagers like VIIRS and microwave sounders such as the Advanced Technology Microwave Sounder. Key specifications include spectral coverage from ~650 to 2550 cm−1 (approximately 3.9–15.4 μm), unapodized resolution near 0.625 cm−1, and a nadir field of view of ~14 km at nadir for footprint sizes consistent with polar orbiting sounders. The instrument electronics and cryocooler subsystems were developed by contractors collaborating with Ball Aerospace, Raytheon, and others, following standards applied in missions like Aqua and Terra.

Data Products and Processing

Raw interferograms are transformed into radiance spectra via Fourier transform algorithms and radiometric calibration chains analogous to methods used for MODIS and IASI processing. Level 1 products provide calibrated radiances; Level 2 delivers geolocated temperature and humidity profiles, cloud parameters, and constituent retrievals (CO2, CH4, O3) using retrieval schemes derived from work at the Jet Propulsion Laboratory, University of Wisconsin–Madison, NOAA/NESDIS, and the Air Resources Laboratory. Data processing pipelines handle instrument line shape characterization, nonlinearity correction, and spectral registration similar to techniques used with CrIS precursor instruments and modern hyperspectral retrieval systems at centers such as CIRA and ECMWF. Reanalysis assimilation of CrIS radiances has been demonstrated in MERRA-2, CFSR, and ERA-Interim style systems. Product dissemination follows protocols used by NASA Earthdata and NOAA CLASS to supply users in meteorology, climate, and atmospheric chemistry.

Scientific Applications

CrIS supports operational forecasting improvements demonstrated at NOAA NCEP, the UK Met Office, and the Korean Meteorological Administration. Climate research applications leverage CrIS spectral accuracy for trend detection in greenhouse gas concentrations and radiative flux studies conducted by groups at Goddard Institute for Space Studies, NOAA GML, and Scripps Institution of Oceanography. Air quality and composition studies integrate CrIS retrievals with data from OMI, TROPOMI, and MLS to study pollution transport, stratosphere–troposphere exchange, and biomass burning events such as those documented in analyses of the 2019–20 Australian bushfires and 2017 California wildfires. Examples of cross‑instrument synergy include combined soundings with AMSU, ATMS, and microwave humidity profiles from SSM/I and GMI to improve convective and boundary‑layer characterization. Studies at institutions like NOAA ESRL and Columbia University use CrIS spectra for radiative transfer model validation and inverse modeling of trace gas fluxes.

Calibration and Validation

Calibration employs onboard blackbody references, cold space views, and vicarious methods including comparisons with radiosonde networks from the Global Climate Observing System and reference instruments such as ground‑based TCCON sites and airborne campaigns like INTEX and ARCTAS. Validation teams from NOAA/NESDIS, NASA AIRS Science Team, and university groups perform intercomparisons with IASI on MetOp, with laboratory standards at NIST, and with field spectrometers used in SORCE and other programs. Long‑term stability assessments reference climate benchmark datasets including GCOS Observing Networks and utilize drift correction approaches employed in missions like AIRS and MODIS.

Mission History and Operators

The CrIS project traces to instrument development efforts funded by NOAA and NASA, with operational deployment on Suomi NPP (launched with the NPP mission partnership) and subsequent flight units aboard JPSS satellites such as NOAA-20. Programmatic oversight involves NOAA NESDIS, NASA STMD, and industrial partners including Raytheon, ITT Exelis, and Ball Aerospace. The instrument program interfaces with international partners including EUMETSAT and CMA (China Meteorological Administration) for data exchange and intercalibration exercises resembling collaborations on IASI and AIRS. CrIS continues to be a critical component of polar orbiting sounding capabilities informing agencies like WMO and regional centers including the Australian Bureau of Meteorology and Environment and Climate Change Canada.

Category:Satellite radiometers