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

From Geos-chem
Jump to: navigation, search
(→‎GEOS-5 and MERRA)
(→‎References)
Line 116: Line 116:
 
=== References ===
 
=== References ===
  
−
* [[GEOS-5 issues]]
+
#[[GEOS-5 issues]]
−
* [[List of GEOS-5 met fields]]
+
#[[List of GEOS-5 met fields]]
−
* [[GEOS-5 met field reprocessing]]
+
#[[GEOS-5 met field reprocessing]]
 +
#[http://acmg.seas.harvard.edu/geos/wiki_docs/geos5/GEOS-5.2.0-File_Specification.pdf GEOS-5 File Specification Document (version 5.2.0)]
 +
#[http://acmg.seas.harvard.edu/geos/wiki_docs/geos5/MERRA_FileSpec_DRAFT_09_02_2008.pdf MERRA File Specification Document]
 +
#[http://disc.sci.gsfc.nasa.gov/daac-bin/DataHoldings.pl MERRA data holdings at GSFC]
  
−
--[[User:Bmy|Bob Y.]] 16:49, 28 July 2010 (EDT)
+
--[[User:Bmy|Bob Y.]] 16:56, 28 July 2010 (EDT)
  
 
== GEOS-4 ==
 
== GEOS-4 ==

Revision as of 20:56, 28 July 2010

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&degl 		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:

  1. GEOS-1 and GEOS-STRAT are now obsolete and no longer supported by GEOS-Chem
  2. GEOS-3 is still supported but we recommend users to migrate to GEOS-4 or GEOS-5.
  3. 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:
  • GEOS-5 operational data: 2004-present; some 2003
  • MERRA reanalysis data: 1979-2010
We regridded to:

GEOS-5 operational data:

MERRA reanalysis data:

  • 4° x 5° with 72 hybrid layers
Strengths:
  • High resolution will facilitate comparison to satellites
  • Convection, optical depth better than in GEOS–4
Weaknesses:
  • Large data volume: 1 day of “raw” data files = 3 GB!

References

  1. GEOS-5 issues
  2. List of GEOS-5 met fields
  3. GEOS-5 met field reprocessing
  4. GEOS-5 File Specification Document (version 5.2.0)
  5. MERRA File Specification Document
  6. MERRA data holdings at GSFC

--Bob Y. 16:56, 28 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:
  • 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”

--Bob Y. 16:49, 28 July 2010 (EDT)

References

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

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:
  • 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

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:
  • Long temporal coverage (10 years)
Weaknesses:
  • Very low model top (10 hPa)
  • Strat-trop exchange was too fast by 2-3X

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:
  • 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 Y. 16:43, 27 July 2010 (EDT)

Retrieved from "https://wiki.seas.harvard.edu/geos-chem/index.php?title=Overview_of_GMAO_met_data_products&oldid=4876"