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 | GEOS-FP (formerly GEOS-5.7.2) | |
---|---|---|---|---|---|---|---|
Notes on GEOS vertical grids | 20 sigma | 26 sigma | 48 sigma | 55 hybrid | 72 hybrid | 72 hybrid or 42 pressure |
72 hybrid |
Native horizontal 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° 1.25° x 1.25° 1° x 1.25° |
0.25° x 0.3125° |
Native file format | Binary | Binary | HDF4-EOS | HDF4-EOS | HDF4-EOS | HDF4-EOS | netCDF4/HDF5 |
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° |
2° x 2.5° 4° x 5° |
0.5° x 0.666° nested 2° x 2.5° 4° x 5° |
4° x 5° | 0.25° x 0.3125° nested 2° x 2.5° 4° x 5° |
Temporal coverage | 1985 - 1995 | 1996 - 1998 | 2000 - 2002 | 1985 - 2007 | 2004 - present | 1979 - 2010 | 2011 - |
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.
- 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).
- 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. 10:28, 19 August 2013 (EDT)
GEOS-FP
MERRA
GEOS-5.2.0
The GEOS-5 family of products
- GEOS5-FP (which we refer to as GEOS-FP) is the current operational GMAO data product. NASA/GMAO is currently producing this product with version 5.11.0 of the GEOS-DAS. GEOS-FP was introduced in 2011 as GEOS-5.7.2, which reflected the version of the GEOS-DAS that was used at the time.
- GEOS-5.2.0 (which we refer to as GEOS-5) was the previous operational data set. This now has been completely replaced by GEOS-FP.
- MERRA is a multi-year reanalysis done with version 5.2.0 of the GEOS-DAS.
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: |
|
Temporal coverage: |
|
We regridded to: |
GEOS-FP operational data
GEOS-5.2.0 data:
MERRA reanalysis data:
|
Strengths: |
|
Weaknesses: |
|
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
- 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.
- 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
- 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 on the GEOS-Chem wiki
- MERRA grid structure
- MERRA file naming convention
- MERRA mainstream and spinup data
- List of MERRA met fields used by GEOS-Chem
- MERRA File Specification Document
- MERRA data holdings at GSFC
- GEOS-5.7.2
- List of GEOS-5.7.2 met fields for use with GEOS-Chem
--Bob Y. 16:33, 2 August 2011 (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
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: |
|
Weaknesses: |
|
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
Removal of support for GEOS-3
This update was tested in the 1-month benchmark simulation v9-01-03h and approved on 09 Mar 2012.
Bob Yantosca wrote:
- As you may know, the GEOS-3 met (for data years 2000-2001) is now several versions behind the current GMAO operational product. If there is no longer a significant demand to keep GEOS-3 met, then I would propose removing the GEOS-3 specific source code (denoted by “#if defined( GEOS_3 )” statements). This will help to clean up the source code, which in turn will facilitate the work that Mike Long and I are doing on the Grid-Independent GEOS-Chem project.
Support for GEOS-3 meteorology will be removed in GEOS-Chem v9-01-03.
--Melissa Payer 12:18, 2 March 2012 (EST)
Summary
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: |
|
Weaknesses: |
|
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: |
|
Weaknesses: |
|
--Bob Y. 16:43, 27 July 2010 (EDT)