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Description

WARNING: To users of the derived product “co_mmr_midtrop” (carbon monoxide mass mixing ratio to dry air [kg/kg] at ~500 hPa). This variable has a significant bias due to a conversion error: the molecular weight of carbon dioxide (CO2, 44.01 g/mol) was used instead of carbon monoxide (CO, 28.01 g/mol). To correct, simply multiply “co_mmr_midtrop” by 28.01/44.01. Alternatively, derive a profile of mass mixing ratio from scratch using the retrieved column density values (“mol_lay/co_mol_lay”) in the Level 2 files. For further questions or concerns please contact the Sounder SIPS at: sounder.sips@jpl.nasa.gov

The CLIMCAPS (Community Long-term Infrared Microwave Coupled Product System) algorithm is used to analyze data from the AIRS (Atmospheric Infrared Sounder). The AIRS instrument is a grating spectrometer (R = 1200) aboard the second Earth Observing System (EOS) polar-orbiting platform, EOS Aqua. The AIRS CLIMCAPS Retrieval Product consists of retrieved estimates of cloud and surface properties, plus profiles of retrieved temperature, water vapor, ozone, carbon monoxide and methane. The temperature profile vertical resolution is 100 levels total between 1100 mb and 0.1 mb, while moisture profile is reported at atmospheric layers between 1100 mb and 300 mb. The horizontal resolution is 50 km.

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.

An AIRS 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.

Product Summary

Platforms
Aqua
Instruments
AIRS
Spatial Extent

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

Geographic Region
GLOBAL
Coordinate System
GEODETIC
Granule Spatial Representation
GEODETIC
Temporal Extent
2002-08-30 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
C1693440795-GES_DISC
Data State
ACTIVE
Number of Files/Granules
2025678
Processing Level
2
Published
Updated
Science Keywords
Tropospheric Ozone ,
Tropopause ,
Methane ,
Atmospheric Ozone ,
Surface Pressure ,
Outgoing Longwave Radiation ,
Surface Temperature ,
Air Temperature ,
Upper Air Temperature ,
Layered Precipitable Water ,
Total Precipitable Water ,
Water Vapor Profiles ,
Cloud Fraction ,
Cloud Top Pressure ,
Cloud Top Temperature ,
Cloud Vertical Distribution ,
Precipitation Rate ,
Emissivity ,
Skin Temperature ,
Sea Surface 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

Barnet, C. (2019). Sounder SIPS: AQUA AIRS IR-only Level 2 CLIMCAPS : Atmosphere, cloud and surface geophysical state V2 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/ILFPVBTDHTDL Date Accessed: 2025-12-14

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
air_pres pressure levels Pa float32 9.9692099683869E+36 N/A N/A
air_pres_h2o H2O vapor pressure levels Pa float32 9.9692099683869E+36 N/A N/A
air_pres_h2o_nsurf Index in air_pres_h2o of the level at the surface. Values at levels beyond this are invalid, representing data below the Earth's surface. 1 int16 -32767 N/A N/A
air_pres_lay pressure at the middle of each layer Pa float32 9.9692099683869E+36 N/A N/A
air_pres_lay_bnds Min and max pressure of each layer Pa float32 9.9692099683869E+36 N/A N/A
air_pres_lay_nsurf Index in air_pres_lay of the layer at the surface. Values for layers beyond this are invalid, representing data below the Earth's surface. 1 int16 -32767 N/A N/A
air_pres_nsurf Index in air_pres of the level at the surface. Values at levels beyond this are invalid, representing data below the Earth's surface. 1 int16 -32767 N/A N/A
air_temp air temperature profile Kelvin float32 9.9692099683869E+36 N/A N/A
air_temp_dof The trace of the averaging kernel matrix as a measure of the number of pieces of information about the air temperature profile provided by the physical retrieval step. 1 float32 9.9692099683869E+36 N/A N/A
air_temp_err air_temp error estimate Kelvin float32 9.9692099683869E+36 N/A N/A
air_temp_qc air_temp QC flag N/A int8 -127 N/A N/A
asc_flag ascending orbit flag: 1 if ascending, 0 descending N/A uint8 255 N/A N/A
asc_node_local_solar_time local apparent solar time at the last ascending node before time_coverage_end in hours from midnight hours float32 9.9692099683869E+36 N/A N/A
asc_node_lon Longitude of the last ascending node of spacecraft orbit before time_coverage_end. degrees_east float32 9.9692099683869E+36 N/A N/A
asc_node_tai93 TAI93 time of the last ascending node of spacecraft orbit before time_coverage_end. seconds since 1993-01-01 00:00 float64 9.9692099683869E+36 N/A N/A
attitude_lbl list of rotational directions (roll, pitch, yaw) N/A OTHER N/A N/A N/A
ch4_dof The trace of the averaging kernel matrix as a measure of the number of pieces of information about the methane profile provided by the physical retrieval step. 1 float32 9.9692099683869E+36 N/A N/A
ch4_mmr_midtrop Methane mass mixing ratio to dry air at 40000 Pa, near the peak of sensitivity kg / kg float32 9.9692099683869E+36 N/A N/A
ch4_mmr_midtrop_err ch4_mmr_midtrop error estimate kg / kg float32 9.9692099683869E+36 N/A N/A
ch4_mmr_midtrop_qc ch4_mmr_midtrop QC flag N/A int8 -127 N/A N/A
cld_frac effective cloud fraction 1 float32 9.9692099683869E+36 N/A N/A
cld_frac_err effective cloud fraction error estimate 1 float32 9.9692099683869E+36 N/A N/A
cld_frac_qc effective cloud fraction QC flag N/A int8 -127 N/A N/A
cld_lay_lbl Cloud layer {top, bottom} N/A OTHER N/A N/A N/A
cld_top_pres cloud top pressure in order of increasing pressure Pa float32 9.9692099683869E+36 N/A N/A
cld_top_pres_err cloud top pressure error estimate 1 float32 9.9692099683869E+36 N/A N/A
cld_top_pres_qc cloud top pressure QC flag N/A int8 -127 N/A N/A
cld_top_temp cloud top temperature Kelvin float32 9.9692099683869E+36 N/A N/A
cld_top_temp_err cloud top temperature error estimate Kelvin float32 9.9692099683869E+36 N/A N/A
cld_top_temp_qc cloud top temperature QC flag N/A int8 -127 N/A N/A
co2_dof The trace of the averaging kernel matrix as a measure of the number of pieces of information about the carbon dioxide profile provided by the physical retrieval step. 1 float32 9.9692099683869E+36 N/A N/A
co_dof The trace of the averaging kernel matrix as a measure of the number of pieces of information about the carbon monoxide profile provided by the physical retrieval step. 1 float32 9.9692099683869E+36 N/A N/A
co_mmr_midtrop Carbon monoxide mass mixing ratio to dry air at 50000 Pa, near the peak of sensitivity kg / kg float32 9.9692099683869E+36 N/A N/A
co_mmr_midtrop_err co_mmr_midtrop error estimate kg / kg float32 9.9692099683869E+36 N/A N/A
co_mmr_midtrop_qc co_mmr_midtrop QC flag N/A int8 -127 N/A N/A
fov_land_frac land fraction over the FOV 1 float32 9.9692099683869E+36 N/A N/A
fov_lat latitude of FOV center degrees_north float32 9.9692099683869E+36 N/A N/A
fov_lat_bnds latitudes of points forming a polygon around the perimeter of the FOV degrees_north float32 9.9692099683869E+36 N/A N/A
fov_lon longitude of FOV center degrees_east float32 9.9692099683869E+36 N/A N/A
fov_lon_bnds longitudes of points forming a polygon around the perimeter of the FOV degrees_east float32 9.9692099683869E+36 N/A N/A
fov_obs_id unique earth view observation identifier for FOV: yyyymmddThhmm.aaExx.f . Includes gran_id plus 2-digit along-track index (01-45), 2-digit cross-track index (01-30), and 1-digit FOV number (1-9). N/A OTHER N/A N/A N/A
fov_surf_alt mean surface altitude wrt earth model over the FOV m float32 9.9692099683869E+36 N/A N/A
fov_surf_alt_sdev standard deviation of surface altitude within the FOV m float32 9.9692099683869E+36 N/A N/A
gp_hgt Geopotential is the sum of the specific gravitational potential energy relative to the geoid and the specific centripetal potential energy. Geopotential height is the geopotential divided by the standard acceleration due to gravity. m float32 9.9692099683869E+36 N/A N/A
gp_hgt_err gp_hgt error estimate m float32 9.9692099683869E+36 N/A N/A
gp_hgt_qc gp_hgt QC flag N/A int8 -127 N/A N/A
h2o_vap_dof The trace of the averaging kernel matrix as a measure of the number of pieces of information about the water vapor profile provided by the physical retrieval step. 1 float32 9.9692099683869E+36 N/A N/A
h2o_vap_tot total precipitable water vapor kg / m2 float32 9.9692099683869E+36 N/A N/A
h2o_vap_tot_err h2o_vap_tot error estimate kg / m2 float32 9.9692099683869E+36 N/A N/A
h2o_vap_tot_qc h2o_vap_tot QC flag N/A int8 -127 N/A N/A
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