Difference between revisions of "Overview of GMAO met data products"

Revision as of 13:55, 20 August 2013

On this page we shall list the features of the various meteorological data products produced by NASA's Global Modeling and Assimilation Office. These products are used to drive GEOS-Chem.

GMAO met field comparison chart

NOTES:

1. GEOS-1, GEOS-STRAT and GEOS-3 are now obsolete and are no longer supported for GEOS-Chem
2. MERRA is a long-term reanalysis done with version GEOS-5.2.0.
3. The new GEOS-FP data product has now replaced the interim GEOS-5.7.2 product. This data product has an increased horizontal resolution (1/4° lat x 5/16° lon).
4. Please also see our Notes regarding GEOS vertical grids wiki page for more information about how the sigma and hybrid grids are defined.

--Bob Y. 14:51, 19 August 2013 (EDT)

GEOS-FP

GEOS-FP (aka GEOS5-FP) is the current GMAO operational data product used with GEOS-Chem.

Summary

NOTES:

1. GEOS-FP was introduced in 2011 as GEOS-5.7.2, which was the version of the GEOS5-GCM used at the time. For more information on the differences between this product and the prior operational product (GEOS-5.2.0), please see: Evolution of the GEOS-5 system from GEOS-5.2.0/MERRA to GEOS-5.7.2 (aka "Fortuna").
2. GMAO also produces a lower-resolution product called "GEOS5-FP-IT" ("forward processing, instrument teams"), which is available at 0.5° x 0.666°. However, this product is not a true operational system because it is "frozen". This means that new scientific updates are not introduced into GEOS5-FP-IT. For GEOS-Chem, we will only use the GEOS-FP product, not only because of its higher resolution, but also because we want to take advantage of any scientific updates that are made to the GEOS-DAS assimilation system.
3. For GEOS-Chem, we only regrid to coarser horizontal reslution. We keep the MERRA vertical grid of 72 layers. GEOS-Chem has the capability to lump vertical vertical levels in the stratosphere to gain computational advantage.

--Bob Y. 12:01, 19 August 2013 (EDT)

References

For more information about GEOS-FP, please see:

1. GEOS5-FP file specification document, Version 1.0 (11 Jun 2013)
2. GEOS-FP on the GEOS-Chem wiki
3. List of GEOS-FP met fields used by GEOS-Chem
4. GEOS-FP grid structure
5. GEOS-FP file naming convention
6. GEOS-FP data file collections (aka file types)
7. GEOS-FP time archiving
8. Glossary of variables produced by the GEOS-DAS

--Bob Y. 11:59, 19 August 2013 (EDT)

MERRA reanalysis

MERRA is a 30-year reanalysis product done created with version 5.2.0 of the GEOS-DAS assimilation system.

Summary

NOTES:

1. For GEOS-Chem, we only regrid to coarser horizontal reslution. We keep the MERRA vertical grid of 72 layers. GEOS-Chem has the capability to lump vertical vertical levels in the stratosphere to gain computational advantage.
2. Some MERRA data files are only available on a fixed pressure grid with 42 layers. We have regridded those fields to 72 layers for use with GEOS-Chem.

--Bob Y. 14:54, 19 August 2013 (EDT)

References

For more information about the MERRA reanalysis product, please see:

1. MERRA File Specification Document (03 Aug 2012)
2. MERRA on the GEOS-Chem wiki
3. List of MERRA met fields used by GEOS-Chem
4. MERRA grid structure
5. MERRA file naming convention
6. MERRA data file collections (aka file types)
7. MERRA time archiving
8. MERRA mainstream and spinup data
9. MERRA data holdings at GSFC
10. Glossary of variables produced by the GEOS-DAS

--Bob Y. 11:48, 19 August 2013 (EDT)

GEOS-5.2.0

GEOS-5.2.0 (which we often refer to simply as "GEOS-5") was the previous operational data set. GMAO's is currently producing the produces the GEOS-FP operational met data product.

Summary

NOTES:

1. The GEOS-5 and MERRA data are kept at 72 vertical levels, and are only regridded to coarser horizontal resolution. However, GEOS-Chem has the capability to lump levels on the fly from 72 to 47 vertical levels. This is done for computational expediency.
2. The new GEOS-5.7.2 data product was officially released in 2011. This data set has increased horizontal resolution (0.25° x 0.3125°), but the same # of vertical levels (72) as the older GEOS-5 and MERRA products.
3. Please also see this document which details the evolution of the GEOS-5 system from GEOS-5.2.0/MERRA to GEOS-5.7.2 (aka "Fortuna").

References

1. List of GEOS-5 met fields used by GEOS-Chem
2. GEOS-5 issues encountered w/r/t GEOS-Chem
3. Reprocessing of GEOS-5 met data for GEOS-Chem (completed Jul 2009)
4. GEOS-5 products page at GMAO
5. GEOS-5 File Specification Document (version 5.2.0)
6. Glossary of variables produced by the GEOS-DAS

--Bob Y. 12:04, 19 August 2013 (EDT)

GEOS-4

GEOS-4 was produced at higher vertical resolution but slightly coarser horizontal resolution than GEOS-3. There are approximately 20 years of GEOS-4 data available to be used with GEOS-Chem. GEOS-4 has been used extensively by the GEOS-Chem community in various applications.

Please see our GEOS-4 wiki page for more information.

Summary

NOTES:

1. The GEOS-4 data are kept at 55 vertical levels, and are only regridded to coarser horizontal resolution. However, GEOS-Chem has the capability to lump levels on the fly from 72 to 30 vertical levels. This is done for computational expediency.

References

1. GEOS-4 on the GEOS-Chem wiki
2. Documents which describe the validation of GEOS-4 met fields in GEOS-Chem
3. GEOS-4 references
4. List of GEOS-4 met fields
5. Availability of GEOS-4 met fields

--Bob Y. 14:07, 19 August 2013 (EDT)

GEOS-3

GEOS-3 was an improvement over GEOS-1 and GEOS-STRAT. However, because GEOS-3 was a pure-sigma model, there were problems in the stratosphere caused by excess noise in the winds. The GEOS-3 product was extensively used in GEOS-Chem for TRACE-P mission analysis.

NOTES:

1. The GEOS-3 data are kept at 48 vertical levels, and are only regridded to coarser horizontal resolution. However, GEOS-Chem has the capability to lump levels on the fly from 48 to 30 vertical levels. This is done for computational expediency.

--Bob Y. 12:41, 29 July 2010 (EDT)

GEOS-1 and GEOS-STRAT

GEOS-1 was the first GMAO met field data product compatible with GEOS-Chem. GEOS-STRAT was a continuation of GEOS-1, but with a finer vertical grid. Both products have been superseded by newer versions of GMAO met products and are no longer supported in GEOS-Chem.

GEOS-1 features

GEOS-STRAT features

--Bob Y. 16:43, 27 July 2010 (EDT)