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Geophysical data products are contained within the AIRS data products. For more information about AIRS data products, view the Data Product Descriptions page. -
AIRS measures the globe twice daily. This means two sets of products are available per day with global coverage.
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All AIRS data products are available within 72 hours of acquisition.
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All AIRS geophysical products are a result of the combined IR/MW retrieval EXCEPT for the microwave-only Standard Products and the AIRS-Only data products.
For more information about the AIRS geophysical products, refer to the AIRS Version 5 Release Level 2 Standard Product QuickStart Guide. Additional information is found on the AIRS Documentation Page on the Goddard Earth Sciences Data Information and Services Center (DISC).
AIRS Carbon Dioxide Product
AIRS measures the distribution of carbon dioxide in the mid troposphere at a nadir resolution of 90 km x 90 km. The AIRS broad swath makes it able to map the global distribution of carbon dioxide every day. The high spectral resolution and stability of AIRS give it extremely high measurement accuracy (about 1.2 ppm) making it ideal for trending carbon dioxide levels and the global distribution.
Data Source
Available in L2 and L3 data products.
Links to data product access points can be found at AIRS CO2 Data.
More information is found on About AIRS CO2.
AIRS Carbon Monoxide Product
A product of the IR stage of the combined IR/MW retrieval. Reported is the retrieved volume mixing ratio profile (ratio of number of carbon monoxide molecules to the number of molecules of air in a unit volume) for 9 layers which are defined by the faces of a carbon monoxide trapezoidal retrieval function. Also reported are CO effective pressure, effective carbon monoxide volume mixing ratio profile and total column carbon monoxide.
Data Source
Available in L2 and L3 data products.
AIRS Cloud Product
The AIRS instrument operationally produces three cloud products related to climate: Fractional Cloud Cover, Cloud Top Pressure, and Cloud Top Temperature. Current research efforts are underway using AIRS data to determine the phase of clouds (liquid, ice, or both), the cloud particle sizes and shapes, and other properties that will help to answer the question about the relevance of clouds to Earth's climate.
Fractional Cloud Cover
This quantity represents the fraction of clouds in a 45 x 45 km area. It is produced as part of the AIRS "cloud-clearing" algorithm in order to produce the Cloud Cleared Infrared Radiances product.
Cloud Top Pressure
Reported on the AMSU FOV (45 x 45 km) for up to two cloud layers.
Cloud Top Temperature
Reported on the AMSU FOV (45 x 45 km) for up to two cloud layers.
Cloud Top Height
Although not directly reported by AIRS, cloud top height can be calculated from cloud top pressure and the atmospheric temperature profile.
Data Source
Available in L2 and L3 data products.
AIRS Dust Product
The AIRS instrument is very sensitive to atmospheric aerosols, such as dust and ash. AIRS aerosols are not produced in geophysical units (e.g. concentration or optical thickness. Dust is expressed as a flag indicating an identifiable amount of material present in the atmosphere.) The detection of the presence of dust is made by comparison of radiances, and the flags originate in the AIRS L1B Product. They are propagated to the Level 2 Standard and Support Products.
Data Source
Available in L1B and L2 data products.
AIRS Methane Product
A product of the IR stage of the combined IR/MW retrieval. Reported is the retrieved volume mixing ratio (ratio of number of methane molecules to the number of molecules of air in a unit volume) for a layer which is defined by the faces of a methane trapezoidal retrieval function. The boundaries of these layers are specified in terms of a 100-level AIRS support pressure array. In V5, there are 7 such layerscorresponding to the 7 trapezoidal retrieval functions utilized for methane. Also reported are the methane effective pressure, and retrieved total column methane. Sensitivity is mainly in the mid tropopsphere which makes it best suited for global daily observations.
Data Source
Available in L2 and L3 data products.
AIRS Water Vapor Product
The atmospheric precipitable water vapor profile is the retrieved mean mass mixing ratio between two standard pressure levels. It is reported on the lower altitude pressure level bounding the layer. Moisture products are reported on the first 15 pressure levels of the 28 available. Total column moisture burden from top of atmosphere to the surface is also reported.
Data Source
Available in L2 and L3 data products.
AIRS Outgoing Longwave Radiation (OLR) and Clear Sky OLR Products
OLR is not directly measured, but is calculated from the retrieved state using a separate rapid algorithm documented in Mehta and Susskind (1999) and NASA Technical Report GSFC/CR-1999-208643. Surface emissivity in spectral regions not measured by AIRS is assumed to be the same as at the nearest spectral point for which an emissivity is obtained. The effective cloud fraction (cloud fraction multiplied by cloud emissivity) is assumed constant throughout the spectrum and is retrieved based on the 11 micron region. Future versions may relax these assumptions.
Data Source
Available in L2 and L3 data products.
AIRS Ozone Product
A product of the IR stage of the combined IR/MW retrieval. The ozone profile is the retrieved volume mixing ratio (ratio of number of ozone molecules to the number of molecules of air in a unit volume) between two standard pressure levels. It is reported on the lower altitude bounding pressure level bounding the layer. Ozone products are reported on all 28 available pressure levels. The value quoted is the mean volume mixing ratio between that level and the next higher level. The value quoted on the lowest altitude pressure level above the surface is the mean volume mixing ratio in the layer bounded by the next higher level and the surface. Also reported is the retrieved total ozone burden which is the integrated column amount of ozone from the top of the atmosphere (TOA = 0.005 mb) to the surface. Ozone retrieval methodology for V5 has significantly changed from V4 and as described in Susskind et al. [2003], namely in the derivation of the first-guess, channel selection, and 'noise propagation threshold' used in the physical (final) retrieval.
Data Source
Available in L2 and L3 data products.
AIRS Sulfur Dioxide Product
The detection of the presence of dust or volcanic SO2 is made by comparison of radiances, and the flags originate in the AIRS L1B Product. They are propagated to the Level 2 Standard and Support Products.
Data indicating which AMSU FOVs and which AIRS spots within the AMSU FOVs indicate the presence of excessive SO2 are located in the AIRS Level 2 Support Product. The entry is BT_diff_SO2 and it is a 3x3 array of brightness temperature differences for each AMSU FOV. The temperature difference tested is:
DTb =Tb 1361.44cm1 - Tb 1433.06cm1
If DTb < -6K the presence of volcanic SO2 is highly likely.
Data Source
Available in L1B and L2 data products.
AIRS Surface Properties Product
The initial surface emissivity over ocean follows the shape of the Masuda model as updated by Wu and Smith (1997) as recomputed at higher spectral resolution by van Delst and Wu. The initial surface emissivity over all other surface classes (e.g. land and ice), has been set by a regression. The subsequent regression retrieval determines a spectral shape that is then used as an updated state for the final retrieval. The regression with shortwave variability has been greatly improved in V5. The final retrieval then adjusts the spectral shape, over land or ocean, with four degrees of freedom. Although algorithm improvements include better treatment of land surface heterogeneity and training over land, the AIRS surface emissivity product over land and ice is still being refined.
Data Source
Available in L2 and L3 data products.
AIRS Temperature Product
The atmospheric temperature profile is reported on the standard pressure levels that are above the altitude of the highest topography in the retrieval FOV. Temperature, pressure, and geopotential height are reported at the surface, at the tropopause, and through the column. All standard temperature products are level quantities, which means that the values are reported at fixed pressure levels.
Data Source
Available in L2 and L3 data products.
