Primary observations and derived variables

On this page you will find tables that detail the primary CLIMCAPS atmospheric observations and variables derived from the CLIMCAPS retrieval.

CLIMCAPS primary variables

CLIMCAPS retrieves multiple Earth surface, cloud and atmospheric state variables from infrared and microwave measurements using Optimal Estimation inversion (Rodgers, 2000). An overview of the CLIMCAPS flowchart is available in this user guide, and a more detailed discussion is available in Smith and Barnet (2019, 2020). CLIMCAPS products can be accessed, downloaded and visualized in Earthdata and WorldView.

In Table 1, we show the primary atmospheric observations that are available in the CLIMCAPS netCDF files, their respective fieldname inside the file, and their vertical level or layer grid.

Temperature, water vapor, ozone, carbon dioxide, carbon monoxide, and cloud products have their own individual user guides. We recommend reading the individual product guides prior to using them in your research.

Table 1: List of atmospheric variables CLIMCAPS retrieves from the cloud cleared radiances

Retrieved Variable	Units	Fieldname	Vertical grid
Temperature	Kelvin	air_temp mw_air_temp	air_pres
Water Vapor	molec/cm²	h2o_vap_mol_lay mw_h2o_vap_mol_lay	air_pres_lay
Ozone	molec/cm²	o3_mol_lay	air_pres_lay
Carbon Dioxide	mol/mol	co2_vmr	air_pres
Carbon Monoxide	molec/cm²	co_mol_lay	air_pres_lay
Cloud fraction	%	cld_frac	n/a
Cloud liquid water	molec/cm²	mw_h2o_liq_mol_lay	air_pres_lay
Cloud top pressure	Pa	for_cld_top_pres_2lay	n/a
Methane	molec/cm²	ch4_mol_lay	air_pres_lay
Nitric Acid	molec/cm²	hno3_mol_lay	air_pres_lay
Nitrous Oxide	molec/cm²	n2o_mol_lay	air_pres_lay
Sulphur Dioxide	molec/cm²	so2_mol_lay	air_pres_lay
Surface emissivity	n/a	surf_ir_emis surf_mw_emis	n/a
Surface reflectivity	n/a	surf_ir_refl surf_mw_emis	n/a
Surface temperature	Kelvin	surf_temp mw_surf_temp	n/a

CLIMCAPS derived variables

The CLIMCAPS netCDF files have several useful derived parameters, which are shown in Table 2. Derived variables are calculated from retrieved variables and may be useful for certain applications.

Table 2: List of variables derived from CLIMCAPS V2 retrieval variables (Table 1). This is not a complete list as the product file contains many derived variables. For a full list, please see the CLIMCAPS V2 product user guide.

Derived Variables	Units	Fieldname	Vertical grid
Methane mass mixing ratio at 400 hPa	kg/kg	ch4_mmr_midtrop	n/a
Cloud top temperature	Kelvin	cld_top_temp	n/a
Carbon monoxide mass mixing ratio at 500 hPa	kg/kg	co_mmr_midtrop	n/a
Geopotential height	meter	gp_hgt	air_pres
Ozone mass mixing ratio	kg/kg	o3_mmr	air_pres
Relative humidity	%	rel_hum	air_pres_h2o
Specific humidity	kg/kg	spec_hum mw_spec_hum	air_pres_h2o
Total column cloud liquid water	Kg/m2	h2o_liq_tot	n/a
Total column ozone	kg/m²	o3_tot	n/a
Total precipitable water	kg/m²	h2o_vap_tot mw_h2o_vap_tot	n/a

References

Smith, N. and Barnet, C. D.: Uncertainty Characterization and Propagation in the Community Long-Term Infrared Microwave Combined Atmospheric Product System (CLIMCAPS), Remote Sensing, 11(10), 1227, doi:10.3390/rs11101227, 2019.
Smith, N. and Barnet, C. D.: CLIMCAPS observing capability for temperature, moisture, and trace gases from AIRS/AMSU and CrIS/ATMS, Atmos. Meas. Tech., 13, 4437–4459, https://doi.org/10.5194/amt-13-4437-2020, 2020