Overview of GMAO met data products
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.
Contents
GMAO met field comparison chart
GEOS-1 | GEOS-STRAT | GEOS-3 | GEOS-4 | GEOS-5 | MERRA | |
---|---|---|---|---|---|---|
Native # of levels | 20 sigma | 26 sigma | 48 sigma | 55 hybrid | 72 hybrid | 72 hybrid |
Native grid | 2° x 2.5° | 2 x 2.5 | 1° x 1° | 1° x 1.25° | 0.5° x 0.666° | 0.5° x 0.666° and 1° x 1.25° |
Native file format | Binary | Binary | HDF4-EOS | HDF4-EOS | HDF4-EOS | HDF4-EOS |
Regridded to | 2° x 2.5° 4 x 5 |
2° x 2.5° 4° x 5° |
1° x 1° nested °2 x 2.5° 4° x 5°l |
2° x 2.5° 4° x 5° |
0.5° x 0.666° nested 2° x 2.5° 4° x 5° |
4° x 5° |
Temporal coverage | 1985 - 1995 | 1996 - 1998 | 2000 - 2002 | 1985 - 2007 | 2004 - present | 1979 - 2010 |
NOTES:
- GEOS-1 and GEOS-STRAT are now obsolete and no longer supported by GEOS-Chem
- GEOS-3 is still supported but we recommend users to migrate to GEOS-4 or GEOS-5.
- MERRA data will be made available at 4 x 5 resolution in the near future. MERRA is a long-term reanalysis done with version GEOS-5.2.0.
--Bob Y. 16:24, 27 July 2010 (EDT)
GEOS-5 and MERRA
GEOS-5 is the current GMAO data product. It is the first ultra-high-resolution data product that GMAO has produced. MERRA is a multi-year reanalysis done with the GEOS-5 GCM (version 5.2.0).
Summary
Assimilation GCM used: | NCAR fvCCM GCM + NASA convection modules |
Native horizontal grid: |
|
Native vertical grid: | 72 hybrid levels; model top at 0.01 hPa |
Native file format: | HDF4-EOS |
Temporal coverage: |
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We regridded to: |
GEOS-5 operational data:
MERRA reanalysis data:
|
Strengths: |
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Weaknesses: |
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NOTES:
- 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.
- In the GEOS-Chem data archive:
- Data from 2003/12/01 to 2008/08/31 is version GEOS-5.1.0
- Data from 2008/09/01 to present is version GEOS-5.2.0
References
- List of GEOS-5 met fields used by GEOS-Chem
- GEOS-5 issues encountered w/r/t GEOS-Chem
- Reprocessing of GEOS-5 met data for GEOS-Chem (completed Jul 2009)
- GEOS-5 products page at GMAO
- GEOS-5 File Specification Document (version 5.1.0)
- GEOS-5 File Specification Document (version 5.2.0)
- MERRA File Specification Document
- MERRA data holdings at GSFC
--Bob Y. 13:06, 29 July 2010 (EDT)
GEOS-4
Summary
Assimilation GCM used: | NCAR fvCCM GCM |
Native horizontal grid: | 1° x 1.25° |
Native vertical grid: | 55 hybrid levels; model top at 0.01 hPa |
Native file format: | HDF4-EOS |
Temporal coverage: | 1985-2006; some 2007 |
We regridded to: | 4° x 5° at 55 sigma layers |
Strengths: |
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Weaknesses: |
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NOTES:
- 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
- Documents which describe the validation of GEOS-4 met fields in GEOS-Chem
- GEOS-4 references
- List of GEOS-4 met fields
- Availability of GEOS-4 met fields
--Bob Y. 12:40, 29 July 2010 (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.
Assimilation GCM used: | NASA/GSFC GEOS–3 GCM |
Native horizontal grid: | 1° x 1° |
Native vertical grid: | 48 sigma levels; model top at 0.01 hPa |
Native file format: | HDF4-EOS |
Temporal coverage: | 2000-2002 |
We regridded to: | 1° x 1° nested grids, 2° x 2.5°, 4° x 5° at 48 sigma layers |
Strengths: |
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Weaknesses: |
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NOTES:
- 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 superceded by newer versions of GMAO met products and are no longer supported in GEOS-Chem.
GEOS-1 features
Assimilation GCM used: | NASA/GSFC GEOS1 GCM |
Native horizontal grid: | 2° x 2.5° |
Native vertical grid: | 20 pure-sigma layers, model top at 10 hPa |
Native file format: | NASA PHOENIX format (binary Fortran unformatted) |
Temporal coverage: | 1985-1995 |
We regridded to: | 4 x 5; 20 pure-sigma layers |
Strengths: |
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Weaknesses: |
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GEOS-STRAT features
Assimilation GCM used: | NASA/GSFC GEOS1 GCM |
Native horizontal grid: | 2° x 2.5° |
Native vertical grid: | 46 pure-sigma layers, model top at 0.1 hPa |
Native file format: | NASA PHOENIX format (binary Fortran unformatted) |
Temporal coverage: | 1996-1997 (some 1998) |
We regridded to: | 4 x 5; 26 pure-sigma layers |
Strengths: |
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Weaknesses: |
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--Bob Y. 16:43, 27 July 2010 (EDT)