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Description

The CLIMCAPS (Community Long-term Infrared Microwave Coupled Product System) algorithm is used to analyze data from the Cross-track Infrared Sounder/Advanced Technology Microwave Sounder (CrIS/ATMS) instruments, also known as CrIMSS (Cross-track Infrared and Microwave Sounding Suite). The CrIS/ATMS instruments used for this product are on board the Suomi National Polar-orbiting Partnership (SNPP) platform and use the Full Spectral Resolution (FSR) data. The CrIS instrument is a Fourier transform spectrometer with a total of 2211 FSR infrared sounding channels covering the longwave (645-1095 cm-1), midwave (1210-1750 cm-1), and shortwave (2000-2550 cm-1) spectral regions. The ATMS instrument is a cross-track scanner with 22 channels in spectral bands from 23 GHz through 183 GHz.

The CLIMCAPS algorithm uses an Optimal Estimation methodology and uses an a-priori first guess to start the process. A CLIMCAPS sounding is comprised of a set of parameters that characterizes the full atmospheric state and includes a variety of geophysical parameters derived from the CrIMSS data. These include surface temperature and infrared emissivity; full atmosphere profiles of temperature, water vapor and ozone; infrared effective cloud top characteristics; carbon monoxide, methane, carbon dioxide, sulfur dioxide, nitrous oxide, and nitric acid.

A level 2 granule has been set as 6 minutes of data, 30 footprints cross track by 45 lines along track. There are 240 granules per day, with an orbit repeat cycle of approximately 16 day.

The CLIMCAPS algorithm uses data from the second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) as a first-guess for the atmospheric state. Because MERRA-2 products typically have a latency from 3 to 7 weeks, so too do the CLIMCAPS products.

Product Summary

Platforms
Suomi-NPP
Instruments
CrIS ,
ATMS
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Location
GLOBAL
Coordinate System
GEODETIC
Granule Spatial Representation
GEODETIC
Temporal Extent
2015-11-02 to Present
Data Partner
Goddard Earth Sciences Data and Information Services Center (formerly Goddard DAAC), Terrestrial Information Systems Laboratory, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/GESDI
Concept ID
C2790892760-GES_DISC
Data State
ACTIVE
Number of Files/Granules
459480
Processing Level
2
Published
Updated
Science Keywords
Tropospheric Ozone ,
Tropopause ,
Atmospheric Chemistry ,
Carbon And Hydrocarbon Compounds ,
Methane ,
Outgoing Longwave Radiation ,
Atmospheric Temperature ,
Surface Temperature ,
Air Temperature ,
Skin Temperature ,
Upper Air Temperature ,
Vertical Profiles ,
Atmospheric Water Vapor ,
Layered Precipitable Water ,
Total Precipitable Water ,
Cloud Properties ,
Cloud Fraction ,
Cloud Top Temperature ,
Precipitation ,
Skin Temperature ,
Ocean Temperature ,
Sea Surface Skin Temperature

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Sounder SIPS: Nadia Smith. (2024). Sounder SIPS: Suomi NPP CrIMSS Level 2 CLIMCAPS Full Spectral Resolution: retrieved atmospheric state V2.1 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/SD6WORV4GX8P Date Accessed: 2026-05-14

Documents

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor Offset
lon_geoid longitude of FOR center on the geoid (without terrain correction) degrees_east float32 9.9692099683869E+36 N/A N/A N/A
mean_anom_wrt_equat spacecraft mean anomaly measured with respect to the ascending node degree float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_air_temp Air temperature on pressure levels from microwave-only retrieval step kelvin float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_air_temp_err mw_air_temp error estimate kelvin float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_air_temp_lay Effective temperature of air pressure layer from mw-only retrieval step, derived from mw_air_temp. See mw_air_temp_err for error estimate. kelvin float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_h2o_vap_mol_lay Water vapor layer total on pressure layers (air_pres_lay) from microwave-only retrieval step. The value for the lowest layer is prorated to represent the number of molecules between the fixed top of that layer listed in air_pres_lay_bnds and the local surface pressure (prior_surf_pres). molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_surf_air_temp Near-surface air temperature (~2 meters above surface) from the MW-only step kelvin float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_surf_air_temp_err mw_surf_air_temp error estimate kelvin float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_surf_mw_emis Microwave surface emissivity from microwave-only retrieval step 1 float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_surf_mw_emis_err mw_surf_mw_emis error estimate 1 float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_surf_temp Skin depth temperature of the Earth surface from microwave-only retrieval step kelvin float32 9.9692099683869E+36 N/A N/A N/A
mw/mw_surf_temp_err mw_surf_temp error estimate kelvin float32 9.9692099683869E+36 N/A N/A N/A
mw_cld_phase Cloud Ice/Water flag from microwave. 0 for liquid clouds or no clouds; 1 for ice clouds. N/A int16 -32767 N/A N/A N/A
mw_h2o_liq_mol_lay Cloud liquid water layer on pressure layers molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
mw_h2o_liq_mol_lay_err mw_h2o_liq_mol_lay error estimate molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
mw_surf_class Microwave spectral surface class. 0 for coastline; 1 for land; 2 for ocean; 3 for first-year sea-ice; 4 for multi-year sea-ice; 5 for snow (higher-freq scattering); 6 for glacier/snow (very low-freq scattering); 7 for snow (lower-freq scattering); N/A int16 -32767 N/A N/A N/A
n2o_mol_lay CLIMCAPS retrieved nitrous oxide layer total on pressure layers (air_pres_lay). The value for the lowest layer is prorated to represent the number of molecules between the fixed top of that layer listed in air_pres_lay_bnds and the local surface pressure (prior_surf_pres). molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
n2o_mol_lay_err n2o_mol_lay error estimate molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
num_cld Number of cloud layers with nonzero cloud fraction 1 int8 -127 N/A N/A N/A
o3_mol_lay CLIMCAPS retrieved ozone layer total on pressure layers (air_pres_lay). The value for the lowest layer is prorated to represent the number of molecules between the fixed top of that layer listed in air_pres_lay_bnds and the local surface pressure (prior_surf_pres). molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
o3_mol_lay_err o3_mol_lay error estimate molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
obs_id unique earth view observation identifier: yyyymmddThhmm.aaExx. Includes gran_id plus 2-digit along-track index (01-45) and 2-digit cross-track index (01-30). N/A OTHER N/A N/A N/A N/A
obs_time_tai93 earth view observation midtime for each FOV seconds since 1993-01-01 00:00 float64 9.9692099683869E+36 N/A N/A N/A
obs_time_utc UTC earth view observation time as an array of integers: year, month, day, hour, minute, second, millisec, microsec N/A uint16 65535 N/A N/A N/A
qc_flag Retrieval quality flag: 0 when quality is good. Bit flag value 1 means bad physical retrieval. Bit values 2 and 8 mean bad MW retrieval. Bit values 4 and 16 mean bad regression retrieval. N/A uint16 65535 N/A N/A N/A
sat_alt satellite altitude with respect to earth model at scan_mid_time m float32 9.9692099683869E+36 N/A N/A N/A
sat_att satellite attitude at scan_mid_time. An orthogonal triad. First element is angle about the +x (roll) ORB axis. +x axis is positively oriented in the direction of orbital flight. Second element is angle about +y (pitch) ORB axis. +y axis is oriented normal to the orbit plane with the positive sense opposite to that of the orbit's angular momentum vector H. Third element is angle about +z (yaw) axis. +z axis is positively oriented Earthward parallel to the satellite radius vector R from the spacecraft center of mass to the center of the Earth. degree float32 9.9692099683869E+36 N/A N/A N/A
sat_azi satellite azimuth angle at the center of the spot (clockwise from North) degree float32 9.9692099683869E+36 N/A N/A N/A
sat_pos satellite ECR position at scan_mid_time m float32 9.9692099683869E+36 N/A N/A N/A
sat_range line of sight distance between satellite and spot center m float32 9.9692099683869E+36 N/A N/A N/A
sat_sol_azi solar azimuth angle at the satellite (clockwise from North) degree float32 9.9692099683869E+36 N/A N/A N/A
sat_sol_zen solar zenith angle at the satellite degree float32 9.9692099683869E+36 N/A N/A N/A
sat_vel satellite ECR velocity at scan_mid_time m s-1 float32 9.9692099683869E+36 N/A N/A N/A
sat_zen satellite zenith angle at the center of the spot degree float32 9.9692099683869E+36 N/A N/A N/A
scan_mid_time TAI93 at middle of earth scene scans seconds since 1993-01-01 00:00 float64 9.9692099683869E+36 N/A N/A N/A
so2_mol_lay CLIMCAPS retrieved sulfur dioxide layer total on pressure layers (air_pres_lay). The value for the lowest layer is prorated to represent the number of molecules between the fixed top of that layer listed in air_pres_lay_bnds and the local surface pressure (prior_surf_pres). molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
so2_mol_lay_err so2_mol_lay error estimate molecules / m2 float32 9.9692099683869E+36 N/A N/A N/A
solar_beta_angle Beta angle for the spacecraft orbit, determining the percentage of the orbit that the spacecraft is in direct sunlight. degree float32 9.9692099683869E+36 N/A N/A N/A
sol_azi solar azimuth angle at the center of the spot (clockwise from North) degree float32 9.9692099683869E+36 N/A N/A N/A
sol_zen solar zenith angle at the center of the spot degree float32 9.9692099683869E+36 N/A N/A N/A
spatial_lbl list of spatial directions (X, Y, Z) N/A OTHER N/A N/A N/A N/A
subsat_lat sub-satellite latitude at scan_mid_time degrees_north float32 9.9692099683869E+36 N/A N/A N/A
subsat_lon sub-satellite longitude at scan_mid_time degrees_east float32 9.9692099683869E+36 N/A N/A N/A
sun_glint_dist distance of sun glint spot to the center of the spot. Fill for night observations. m float32 9.9692099683869E+36 N/A N/A N/A
sun_glint_lat sun glint spot latitude at scan_mid_time. Fill for night observations. degrees_north float32 9.9692099683869E+36 N/A N/A N/A
sun_glint_lon sun glint spot longitude at scan_mid_time. Fill for night observations. degrees_east float32 9.9692099683869E+36 N/A N/A N/A
surf_air_temp Air temperature at Earth surface pressure derived from air_temp and prior_surf_pres kelvin float32 9.9692099683869E+36 N/A N/A N/A
surf_alt mean surface altitude wrt earth model over the FOR m float32 9.9692099683869E+36 N/A N/A N/A
surf_alt_sdev standard deviation of surface altitude within the FOR m float32 9.9692099683869E+36 N/A N/A N/A
surf_freq_mw Microwave surface emissivity frequencies (hinge points) Hz float32 9.9692099683869E+36 N/A N/A N/A
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