Overview of GMAO met data products

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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

NASA/GMAO ceased production of GEOS-5.2.0 as of June 2013. Therefore, you will not be able to use GEOS-5.2.0 to run GEOS-Chem global or nested grid simulations for model dates after June 2013. But you can still run GEOS-Chem simulations using our archive of GEOS-5 meteorology.

The MERRA reanalysis product ceased production in mid-2015. It was superseded by MERRA-2 (aka GEOS-5.12.4), which is now the current GMAO reanalysis product.

The current operational GMAO met data product is now what we call GEOS-FP, which corresponds to GEOS-5.7.2 and later versions. We are processing GEOS-FP data for 2012 up to present day. You will be able to use GEOS-FP for both global and hi-res (0.25° x 0.3125°) nested-grid simulations in GEOS-Chem v9-02 and later GEOS-Chem versions.


The following table is a quick summary of the GMAO meteorological data products that have been used to drive GEOS-Chem simulations. For a more detailed listing of the GMAO operational data products by GMAO version number, please see our Version history of GMAO met data products wiki page.

  GEOS-1 GEOS-STRAT GEOS-3 GEOS-4 GEOS-5 MERRA MERRA-2 GEOS-FP
Data product type Operational Operational Operational Operational Operational Reanalysis Reanalysis Operational
Is this data still being produced? NO NO NO NO NO NO YES YES
Is this data still compatible with GEOS-Chem? NO NO NO YES YES YES YES YES
Native vertical grid 20 sigma 26 sigma 48 sigma 55 hybrid 72 hybrid 72 hybrid or
42 pressure
72 hybrid 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°
0.5° x 0.625° 0.25° x 0.3125°
Native file format Binary Binary HDF4-EOS HDF4-EOS HDF4-EOS HDF4-EOS netCDF4/HDF5 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° 0.5° x 0.625° global
0.5° x 0.625° nested
2° x 2.5°
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 - 2012
partial 2003
partial 2013
1979 - present;
we have archived
up to 2010
1979 - present 2012 - present

NOTES:

  1. This table only lists the met fields produced by NASA/GMAO. GEOS-Chem also can perform simulations for GCAP, with met fields archived from one or more different GISS-GCM model simulations. Please see our GCAP wiki page for more information.
  2. GEOS-1, GEOS-STRAT and GEOS-3 are now obsolete and are no longer supported for GEOS-Chem.
  3. MERRA is a long-term reanalysis done with version GEOS-5.2.0. It is no longer being produced.
  4. MERRA-2 is a long-term reanalysis done with version GEOS-5.12.4.
  5. 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).
  6. Please also see our GEOS-Chem vertical grids wiki page for more information about how the sigma and hybrid grids are defined.

--Bob Yantosca (talk) 17:43, 7 December 2016 (UTC)

GEOS-FP

GEOS-FP is the GEOS-Chem data archive corresponding the GMAO GEOS-5 FP ("forward processing") met data product. This is the current operational GMAO data product that can be used to drive GEOS-Chem simulations.

Summary

GEOS-Chem met archive name: GEOS-FP
GMAO data assimilation system that was used to create these data files: GEOS Data Assimilation System (GEOS-DAS)
Native horizontal grid: 0.25° (lat) x 0.3125° (lon)
Native vertical grid: 72 hybrid levels; model top at 0.01 hPa
Native file format: netCDF4 (based on HDF5)
Temporal coverage: 2011-present
We regridded to:
Strengths:
  • Ultra-high resolution will facilitate comparison to satellites
  • Detailed nested-grid simulations with GEOS-Chem are possible at 0.25° x 0.3125° resolution
Weaknesses:
  • Large data volume: 1 day of GEOS-FP “raw” data files for GEOS-Chem > 21 GB!

NOTES:

  1. GEOS-FP was introduced in 2011 as GEOS-5.7.2, which was the version of the GEOS5-DAS 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 resolution. 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.
  4. Please also see our Version history of GMAO met data products wiki page for more information about the GMAO data versions that are contained in our GEOS-FP archive.

--Bob Yantosca (talk) 19:24, 23 November 2016 (UTC)

References

For more information about the GMAO "forward processing" data product, 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
  9. Molod, A., L. Takacs, M. Suarez, J. Bacmeister, I. Song, and A. Eichmann, The GEOS-5 Atmospheric General Circulation Model: Mean Climate and Development from MERRA to Fortuna, Technical Report Series on Global Modeling and Data Assimilation, 28, Ed: Max J. Suarez, NASA GMAO, Goddard Space Flight Center, Greenbelt, MD, April 2012. (PDF)

--Bob Yantosca (talk) 19:22, 23 November 2016 (UTC)

MERRA-2 reanalysis

MERRA-2 is the GEOS-Chem data archive corresponding to the GMAO MERRA-2 reanalysis met data product. This is the current GMAO reanalysis data set. It contains more than 30 years of assimilated data that can be used to drive GEOS-Chem simulations.

Summary

GEOS-Chem met archive name: MERRA-2
GMAO data assimilation system that was used to create these data files: GEOS Data Assimilation System (GEOS-DAS)
Native horizontal grid: 0.5° (lat) x 0.625° (lon)
Native vertical grid: 72 hybrid levels; model top at 0.01 hPa
Native file format: netCDF4 (based on HDF5)
Temporal coverage: 1980's thru 2010's
We are regridding to:
Strengths:
  • Ultra-high resolution will facilitate comparison to satellites
  • Detailed nested-grid simulations with GEOS-Chem are possible at 0.25° x 0.3125° resolution
Weaknesses:
  • Large data volume

NOTES:

  1. Please also see our Version history of GMAO met data products wiki page for more information about the GMAO data versions that are contained in our GEOS-FP archive.

--Bob Yantosca (talk) 20:18, 23 November 2016 (UTC)

References

For more information about the MERRA-2 reanalysis data product, please see:

  1. MERRA-2 on the GEOS-Chem wiki
  2. List of MERRA-2 met fields used by GEOS-Chem
  3. MERRA-2 grid structure
  4. MERRA-2 file naming convention
  5. MERRA-2 data file collections (aka file types)
  6. MERRA-2 time archiving
  7. Glossary of variables produced by the GEOS-DAS

--Bob Yantosca (talk) 21:00, 9 February 2016 (UTC)

MERRA reanalysis

The MERRA reanalysis product ceased in mid-2015. It has been superseded by MERRA-2 (aka GEOS-5.12.4), which is now the current GMAO reanalysis product.

Summary

GEOS-Chem met archive name: MERRA
GMAO data assimilation system that was used to create these data files: GEOS Data Assimilation System (GEOS-DAS)
  • Version GEOS-5.3.0, used to create 3 separate data streams:
    • MERRA100: 01 Jan 1979 - 31 Dec 1992
    • MERRA200: 01 Jan 1993 - 31 Dec 2000
    • MERRA300: 01 Jan 2001 - present (scheduled to be turned off in 2015)
Native horizontal grid:
Native vertical grid:
  • 1 layer (surface fields)
  • 72 hybrid levels; model top at 0.01 hPa
  • 42 pressure levels (certain 3-D fields, such as moist quantities)
Native file format: HDF4-EOS
Temporal coverage: 1979-May 2015
  • NOTE: the GEOS-Chem data archive only includes data to the end of 2013.
We regridded to:
Strengths:
  • High resolution will facilitate comparison to satellites
  • Convection, optical depth better than in GEOS–4
Weaknesses:
  • Large data volume: 1 day of MERRA “raw” data files > 2 GB!

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.
  3. Please also see our Version history of GMAO met data products wiki page for more information about the individual data versions that are part of the MERRA archive.

--Bob Yantosca (talk) 20:23, 23 November 2016 (UTC)

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 Yantosca (talk) 20:23, 23 November 2016 (UTC)

GEOS-5

NASA/GMAO ceased production of GEOS-5.2.0 data as of June 2013. Therefore, you will not be able to use GEOS-5.2.0 met fields to run global or nested grid simulations for model dates after June 2013. But you can still run GEOS-Chem simulations using our archive of GEOS-5 meteorology for years 2004 through mid-2013.

The current operational GMAO met data product is now what we call GEOS-FP, which corresponds to GEOS-5.7.2 and later versions). We are processing GEOS-FP data for 2012 up to present day. You will be able to use GEOS-FP for both global and hi-res (0.25° x 0.3125°) nested-grid simulations in GEOS-Chem v9-02 and later GEOS-Chem versions.

GEOS-5 is the GEOS-Chem data archive corresponding to the GMAO GEOS-5.1.0 and GEOS-5.2.0 data products.

Summary

GEOS-Chem met archive name: GEOS-5
GMAO data assimilation system that was used to create these data files: GEOS Data Assimilation System (GEOS-DAS)
Native horizontal grid: 0.5° x 0.666°
Native vertical grid: 72 hybrid levels; model top at 0.01 hPa
Native file format: HDF4-EOS
Temporal coverage:
  • 2004-2012
  • Partial coverage for 2003 and 2013
We regridded to:
Strengths:
  • High resolution will facilitate comparison to satellites
  • Convection, optical depth better than in GEOS–4
Weaknesses:

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").
  4. Please also see our Version history of GMAO met data products wiki page for more information about the individual data versions that are part of the GEOS-5 archive.

--Bob Yantosca (talk) 20:27, 23 November 2016 (UTC)

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

GMAO no longer produces GEOS-4 data. But you can still run GEOS-Chem simulations using our 20-year archive of GEOS-4 meteorology.

The current operational GMAO met data product is now what we call GEOS-FP, which corresponds to GEOS-5.7.2 and later versions. We are processing GEOS-FP data for 2012 up to present day. You will be able to use GEOS-FP for both global and hi-res (0.25° x 0.3125°) nested-grid simulations in GEOS-Chem v9-02 and later GEOS-Chem versions.

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

GEOS-Chem met archive name: GEOS-4
GMAO data assimilation system that was used to create these data files: 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:
Strengths:
  • Long temporal horizon – 20 years of consistent met data
  • U and V winds are 6-hr averages, not instantaneous
  • Much better STE than any prior GEOS met fields
Weaknesses:
  • Convection variables totally different than GEOS–3
  • GMAO was unhappy w/ the convection results
  • Cloud OD’s are too low; J-values, chemistry are “too hot”

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.

--Bob Yantosca (talk) 20:32, 23 November 2016 (UTC)

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 Yantosca (talk) 20:32, 23 November 2016 (UTC)

GEOS-3

GMAO no longer produces GEOS-3 data. GEOS-Chem v9-01-03 (released on 12 Sep 2014) and higher versions no longer support the GEOS-3 met data.

The current operational GMAO met data product is now what we call GEOS-FP, which corresponds to GEOS-5.7.2 and later versions. We are processing GEOS-FP data for 2012 up to present day. You will be able to use GEOS-FP for both global and hi-res (0.25° x 0.3125°) nested-grid simulations in GEOS-Chem v9-02 and later GEOS-Chem versions.

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.

GEOS-Chem met archive name: GEOS-3
GMAO data assimilation system that was used to create these data files: 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:
Strengths:
  • High resolution made 1° x 1deg; nested sims possible
  • Higher model top
Weaknesses:
  • P to sigma vertical interpolation had to be done
  • STE still not realistic
  • U, V winds were very noisy at the top of the atmosphere

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 Yantosca (talk) 20:38, 23 November 2016 (UTC)

GEOS-1 and GEOS-STRAT

GMAO no longer produces GEOS-1 or GEOS-STRAT data. GEOS-1 and GEOS-STRAT are no longer supported in GEOS-Chem.

The current operational GMAO met data product is now what we call GEOS-FP, which corresponds to GEOS-5.7.2 and later versions. We are processing GEOS-FP data for 2012 up to present day. You will be able to use GEOS-FP for both global and hi-res (0.25° x 0.3125°) nested-grid simulations in GEOS-Chem v9-02 and later GEOS-Chem versions.

GEOS-1 was the first GMAO met field data product compatible with GEOS-Chem. GEOS-STRAT was a continuation of GEOS-1 (officially known as "GEOS-1-STRAT"), 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-Chem met archive name: GEOS-1
GMAO data assimilation system that was used to create these data files: 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° with 20 pure-sigma layers
Strengths:
  • Long temporal coverage (10 years)
Weaknesses:
  • Very low model top (10 hPa)
  • Strat-trop exchange was too fast by 2-3X

--Bob Yantosca (talk) 20:56, 23 November 2016 (UTC)

GEOS-STRAT features

GEOS-Chem met archive name: GEOS-STRAT
GMAO data assimilation system that was used to create these data files: 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° with 26 pure-sigma layers
Strengths:
  • Higher model top, better stratospheric representation
Weaknesses:
  • Vertical grid did not correspond to GEOS–1
  • STE still too fast by 2-3X
  • Surface data had a 6-hr temporal resolution, we had to interpolate to a 3-hr temporal resolution ourselves

--Bob Yantosca (talk) 20:58, 23 November 2016 (UTC)