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Description

The CLIMCAPS (Community Long-term Infrared Microwave Coupled Product System) algorithm is used to analyze data from the AIRS (Atmospheric Infrared Sounder) and AMSU (Advanced Microwave Sounding Unit). The AIRS instrument is a grating spectrometer (R = 1200) aboard the second Earth Observing System (EOS) polar-orbiting platform, EOS Aqua. The AIRS in combination with the AMSU constitutes an innovative atmospheric sounding group of infrared and microwave sensors. The AIRS Standard 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 granule has been set as 6 minutes of data, 30 footprints cross track by 45 lines along track for each of the approximate 2378 channels. There are 240 granules per day, with an orbit repeat cycle of approximately 16 day

Product Summary

Platforms
Aqua
Instruments
AIRS ,
AMSU-A
Spatial Extent

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

Geographic Region
GLOBAL
Coordinate System
GEODETIC
Granule Spatial Representation
GEODETIC
Temporal Extent
2002-08-31 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
C2790934208-GES_DISC
Data State
ACTIVE
Number of Files/Granules
1212925
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: AQUA AIRS IR + MW Level 2 CLIMCAPS: Retrieved atmospheric state V2.1 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/J7GVFM11OGIX 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_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_temp_lay Effective temperature of air pressure layer derived from air_temp. See air_temp_err for error estimate. kelvin float32 9.9692099683869E+36 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
aux/a0_cloud intercept of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/aeff_1 A_eff(1st eta step) 1 float32 9.9692099683869E+36 N/A N/A
aux/aeff_end A_eff(last eta step) 1 float32 9.9692099683869E+36 N/A N/A
aux/air_mol_lay Layer total of air in each pressure layer (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
aux/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
aux/air_temp CLIMCAPS retrieved air temperature profile on standard pressure levels (air_pres) without adjustment for local surface pressure (prior_surf_pres). If the final level pressure in the element of air_pres indexed by air_pres_lay_nsurf is greater than the local surface pressure (prior_surf_pres) then this represents the temperature at an extrapolated level below the surface. kelvin float32 9.9692099683869E+36 N/A N/A
aux/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
aux/air_temp_err air_temp error estimate kelvin float32 9.9692099683869E+36 N/A N/A
aux/ampl_eta cloud clearing noise amplification factor 1 float32 9.9692099683869E+36 N/A N/A
aux/bad_mw_ret Flag for bad microwave retrieval from bits 2 and 4 (values 2 and 8) of qc_flag. N/A uint8 255 N/A N/A
aux/bad_phys_ret Flag for bad physical retrieval from bit 1 (value 1) of qc_flag. N/A uint8 255 N/A N/A
aux/bad_reg_ret Flag for bad regression retrieval bits 3 and 5 (values 4 and 16) of qc_flag. N/A uint8 255 N/A N/A
aux/blue_spike_fire Blue spike fire signal strength. Experimental. 1 float32 9.9692099683869E+36 N/A N/A
aux/bl_mult Bottom layer multiplier 1 float32 9.9692099683869E+36 N/A N/A
aux/bt2 RMS(T(p) f/IR.ret - T(p) f/ AMSU.ret) 1 float32 9.9692099683869E+36 N/A N/A
aux/c2h6_dbt Brightness temperature difference near 823 cm-1 indicating ethane. Values over +0.05 K are potential detections. Experimental. kelvin float32 9.9692099683869E+36 N/A N/A
aux/c3h6_dbt Brightness temperature difference near 911 cm-1 indicating propylene. Values over +0.05 K are potential detections. Experimental. kelvin float32 9.9692099683869E+36 N/A N/A
aux/c5h8_dbt Brightness temperature difference near 893 cm-1 indicating isoprene. Values over +0.05 K are potential detections. Experimental. kelvin float32 9.9692099683869E+36 N/A N/A
aux/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
aux/chi2_ch4 Methane chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_co Carbon monoxide chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_co2 Carbon dioxide chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_h2o Water vapor chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_hno3 Nitric acid chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_n2o Nitrous oxide chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_o3 Ozone chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_so2 Sulfur dioxide chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_temp Temperature profile chi^2 of alpha(1)=f(alpha(2)) fitting 1 float32 9.9692099683869E+36 N/A N/A
aux/cldfrc_500 Total cloud fraction over FOR below 500 hPa 1 float32 9.9692099683869E+36 N/A N/A
aux/cldfrc_tot Total cloud fraction over FOR 1 float32 9.9692099683869E+36 N/A N/A
aux/clim_co2_mmr Assumed carbon dioxide concentration kg / kg float32 9.9692099683869E+36 N/A N/A
aux/clim_surf_ir_emis Infrared surface emissivity from the climatology first guess 1 float32 9.9692099683869E+36 N/A N/A
aux/clim_surf_ir_refl infrared surface reflectivity from the climatology first guess 1 float32 9.9692099683869E+36 N/A N/A
aux/clim_surf_ir_wnum Surface infrared emissivity frequencies (hinge points) for the climatology first guess cm-1 float32 9.9692099683869E+36 N/A N/A
aux/clim_surf_ir_wnum_cnt Number of infrared surface emissivity frequencies for the climatology first guess 1 int16 -32767 N/A N/A
aux/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
aux/co2_vmr Carbon dioxide volume mixing ratio on pressure levels. Multiply by 1.0e06 to convert to ppm m3 / m3 float32 9.9692099683869E+36 N/A N/A
aux/co2_vmr_err co2_vmr error estimate m3 / m3 float32 9.9692099683869E+36 N/A N/A
aux/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
aux/dry_air_mol_lay Layer total of dry air in each pressure layer (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
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