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Notice: Version 5 Data Release

Announcement for the release of AIRS Version 5

The AIRS Project and Goddard Earth Sciences Data and Information Service Center (GES DISC) are pleased to announce the release of Collection 5 of the AIRS Data Products.

Collection 5, derived from the AIRS Project’s latest software release, Version 5, contains many additions and refinements when compared to AIRS Collection 3 (Version 4) data products. These include enhanced Level 2 temperature data products over land and polar regions, first-time retrievals of carbon monoxide methane, improvements to ozone retrievals, and improved error and quality flag parameterization overall. A summary of Collection 5 improvements is covered at the end of this message.

Collection 5 Data Processing

The GES DISC is already actively processing the AIRS forward stream for Collection 5. In addition, all the Level 1 AIRS products have been reprocessed, and reprocessing of higher level products (Levels 2 and 3) is well under way.

AIRS Collection 5 data is available through:

Collection 3 Data Processing

The GES DISC will continue producing the AIRS Collection 3 (Version 4) products through 08/31/2007, completing five-years of AIRS data in Collection 3. After this date, only the Collection 5 will continue to be produced. All AIRS Collection 3 products will continue to be orderable from the GES DISC though 10/31/2007. After that date, Collection 3 Level 1B data products will no longer be available. AIRS Level 2 and Level 3 data products from Collection 3 will continue to be available beyond this date.

If you have any questions please contact the GES DISC user services:

GES DISC Help Desk
Code 610.2
NASA/Goddard Space Flight Center
Greenbelt, MD 20771

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Summary of Collection 5 AIRS Data Product Enhancements

Several improvements have been made to AIRS Data Products with the Collection 5 release. They are summarized below. Additional information pertaining to Collection 5 data and documentation may be accessed via:

Level 1B Radiance Products

Version 5 Level 1B AIRS radiance products now contain flags indicating detection of (volcanic) SO2, and a dust flag and dust score.

The AMSU-A Level 1B antenna brightness temperature product now includes a side-lobe correction factor and improved temperature error calculation.

Level 2 Data Products

Version 5 enhances Level 2 temperature profile yield and quality over the polar regions and over land. Improved quality factors facilitate the filtering of data and provide finer vertical discrimination of the point at which the retrieval begins to encounter difficulties, resulting in a smoother gradient in yield from the top of the atmosphere to the surface.

Level 2 moisture retrieval quality and error estimates are also improved. The saturation equilibrium profile calculation has been corrected. In addition, a verticality profile is provided. This is a vector computed by summing the columns of the averaging kernel and indicates the vertical location of the maximum sensitivity of the product. Its magnitude is a measure of the fraction of the product determined from the data as opposed to the first guess.

Ozone retrieval methodology has been significantly changed, resulting in reduced biases in total burden at high Southern latitudes and globally in the mid to lower troposphere. Verticality and the degrees of freedom (the sum of the diagonal elements of the averaging kernel) provide additional measures of sensitivity and fraction due to retrieval as a function of altitude.

Errors identified in the Version 4 release Level 3 relative humidity and Level 2 outgoing longwave radiation have been corrected.

New Level 2 and Level 3 Data Products

Version 5 introduces new trace gas products in Level 2 and Level 3: carbon monoxide and methane. The total column burden and profiles of both are provided, along with their verticality and degrees of freedom. The carbon monoxide layers have been chosen to match those of MOPITT to facilitate cross-comparison.

Version 5 introduces the new Level 3 Quantization Product.  This product is not the simple means and standard deviations of Level 2 products averaged over space and time that are available in the Level 3 Standard Product.  It offers instead a cluster analysis of those Level 2 products, capturing the atmospheric variability as a set of states.

Version 5 also introduces the new Calibration Subset Product.  This product provides AIRS/AMSU/VIS spectra that have been selected because the field of view satisfies one of several criteria: cloud-free, near a calibration site, contains very high clouds or a random sample to achieve globally balanced coverage.  The selection criteria are also included in the product.

Date of Notice: 2007-07-26


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