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MERRA Products

Analysis Files History Files Chemistry Forcing Files Legend
SPSNOW Diagnostic Error

During the MERRA production, the variable SPSNOW was found to be producing incorrect values, and was patched in the middle of production. Incorrect SPSNOW data occur during the following periods:

19790101-19840101
19890101-19931201
19980101-20011001

SPSNOW is the spurious snow source used to maintain stability and balance in the mass budget. In general it should be a very small term and is included in the output to provide more accurate water budgets.

This error exist is in the data in the MERRA archives, but there are plans to correct the files.

 The Modern Era Retrospective-analysis for Research and Applications (MERRA)

The MERRA products are generated using Version 5.2.0 of the GEOS-5 DAS with the model and analysis each at 1/2x2/3 degrees resolution. Three-dimensional analyses are generated every 6 hours, and 3- dimensional diagnostics, describing the radiative and physical properties of the atmosphere, are 3-hourly. The product suite includes analyses on thenative vertical grid as well on pressure surfaces. Two-dimensional data, including surface, fluxes, and vertical integrals, are produced hourly. The product suite includes monthly and monthly diurnal files. The MERRA production is being conducted in 3 separate streams, 1979 - 1989;1989 - 1998; 1998 - present.Data are being uploaded to the MDISC after undergoing quality assurance in the GMAO.

More information, including an FAQ and the file specification document that explains each of the products in detail, is available at the MERRA web site at the GMAO.

*See Documentation on how to acknowledge the data provider.

Data Information

The EOS Data and Information System (EOSDIS) distribute data through the Distributed Active Archive Centers (DAACs) in the Hierarchical Data Format (HDF) and the Hierarchical Data Format - Earth Observing System (HDF-EOS) as the standard for Earth science data generated by EOS instruments. All the MERRA data products are in HDF and HDF-EOS format.

 

  • The variables that are in each file of MERRA data type, its unit and approximate size are in the data product page linked from the descriptive short name.
  • Click on the red check markto go to the data holding for that access method for the particular product.

 

Short Name

Standard Name

Description

Data Subset

OPeNDAP

GDS

Mirador

Time-independent Variables - These are prescribed 2-dimensional fields that do not vary during the reanalysis.
MAC0NXASM

const_2d_asm_Nx

MERRA DAS 2d constants

Constant_HDF_File
Analysis Files - These are the fields resulting from the GSI analyses performed at the four synoptic times. They are produced on the native horizontal grid and on both model levels and pressure levels in the vertical. The data on model levels are the values actually analyzed.
MAI6NVANA inst6_3d_ana_Nv MERRA 3D analyzed state, meteorology, instantaneous, on model levels, at native resolution red check mark red check mark red check mark red check mark
MAI6NPANA
MAIMNPANA
MAIUNPANA
inst6_3d_ana_Np
instM_3d_ana_Np
instU_3d_ana_Np
MERRA 3D analyzed state, meteorology, instantaneous, on pressure levels, at native resolution

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History Files - These histories are produced from the GCM during the “corrector” segment of the IAU cycle. All collections in this group are at reduced horizontal resolution and 3-D fields are on pressure levels.
MAI3CPASM
MAIMCPASM
MAIUCPASM
inst3_3d_asm_Cp
instM_3d_asm_Cp
instU_3d_asm_Cp
MERRA 3D IAU State, meteorology, instantaneous, on pressure levels, at reduced resolution

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MAT3CPCLD
MATMCPCLD
MATUCPCLD
tavg3_3d_cld_Cp
tavgM_3d_cld_Cp
tavgU_3d_cld_Cp
MERRA 3D IAU diagnostic, cloud properties, time averaged, on pressure levels, at reduced resolution

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MAT3CPMST
MATMCPMST
MATUCPMST
tavg3_3d_mst_Cp
tavgM_3d_mst_Cp
tavgU_3d_mst_Cp
MERRA 3D IAU diagnostic, moist physics, time averaged, on pressure levels, at reduced resolution

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MAT3CPRAD
MATMCPRAD
MATUCPRAD
tavg3_3d_rad_Cp
tavgM_3d_rad_Cp
tavgU_3d_rad_Cp
MERRA 3D IAU diagnostic, radiation, time averaged, on pressure levels, at reduced resolution

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MAT3CPTRB
MATMCPTRB
MATUCPTRB
tavg3_3d_trb_Cp
tavgM_3d_trb_Cp
tavgU_3d_trb_Cp
MERRA 3D IAU diagnostic, turbulence time averaged, on pressure levels, at reduced resolution

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MAT3CPTDT
MATMCPTDT
MATUCPTDT
tavg3_3d_tdt_Cp
tavgM_3d_tdt_Cp
tavgU_3d_tdt_Cp
MERRA 3D IAU tendency, temperature, time averaged, on pressure levels, at reduced resolution

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MAT3CPUDT
MATMCPUDT
MATUCPUDT
tavg3_3d_udt_Cp
tavgM_3d_udt_Cp
tavgU_3d_udt_Cp
MERRA 3D IAU tendency, wind component, time averaged, on pressure levels, at reduced resolution red check mark
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MAT3CPQDT
MATMCPQDT
MATUCPQDT
tavg3_3d_qdt_Cp
tavgM_3d_qdt_Cp
tavgU_3d_qdt_Cp
MERRA 3D IAU tendency, specific humidity, time averaged, on pressure levels, at reduced resolution red check mark
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MAT3CPODT
MATMCPODT
MATUCPODT
tavg3_3d_odt_Cp
tavgM_3d_odt_Cp
tavgU_3d_odt_Cp
MERRA 3D IAU tendency, ozone, time averaged, on pressure levels, at reduced resolution red check mark
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MAT1NXSLV
MATMNXSLV
MATUNXSLV
tavg1_2d_slv_Nx
tavgM_2d_slv_Nx
tavgU_2d_slv_Nx
MERRA 2D IAU diagnostic, single level meteorology, time averaged, single level, at native resolution red check mark
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MAT1NXFLX
MATMNXFLX
MATUNXFLX
tavg1_2d_flx_Nx
tavgM_2d_flx_Nx
tavgU_2d_flx_Nx
MERRA 2D IAU diagnostic, surface fluxes, time averaged, single level, at native resolution red check mark
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MAT1NXRAD
MATMNXRAD
MATUNXRAD
tavg1_2d_rad_Nx
tavgM_2d_rad_Nx
tavgU_2d_rad_Nx
MERRA 2D IAU diagnostic, radiation surface and TOA, time averaged, single level, at native resolution red check mark
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MAT1NXLND
MATMNXLND
MATUNXLND
tavg1_2d_lnd_Nx
tavgM_2d_lnd_Nx
tavgU_2d_lnd_Nx
MERRA 2D IAU diagnostic, land only states and diagnostics, time averaged, single level, at native resolution red check mark
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MAT1NXINT
MATMNXINT
MATUNXINT
tavg1_2d_int_Nx
tavgM_2d_int_Nx
tavgU_2d_int_Nx
MERRA IAU 2D vertical integrals and budget terms, time averaged, single level, at native resolution red check mark
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MAI1NXINT
MAIMNXINT
MAIUNXINT
inst1_2d_int_Nx
instM_2d_int_Nx
instU_2d_int_Nx
MERRA IAU 2D vertical integrals and budget terms, instantaneous, single level, at native resolution red check mark
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Chemistry Forcing Files - These histories are intended for forcing off-line chemistry/aerosol models with the results of the reanalysis. Like other histories, they are produced from the GCM during the “corrector” segment of the IAU cycle.
MAC0FXCHM const_2d_chm_Fx MERRA 2-D invariants on chemistry grid Constant_HDF_File
MAT3FVCHM tavg3_3d_chm_Fv MERRA chem 3D IAU states cloud precip, time averaged, 3D model levels, at reduced FV resolution

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MAT3FECHM tavg3_3d_chm_Fe MERRA chem 3D IAU, precip mass flux, time averaged, 3D model levels, at reduced FV resolution red check mark red check mark red check mark red check mark
MAT3FXCHM
MATMFXCHM
MATUFXCHM
tavg3_2d_chm_Fx
tavgM_2d_chm_Fx
tavgU_2d_chm_Fx
MERRA chem 2d IAU diagnostics, fluxes and meteorology, time averaged, single level, at reduced FV resolution
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MAT3NVCHM tavg3_3d_chm_Nv MERRA Chem 3D IAU C-Grid Wind and Mass Flux, time averaged, 3D model levels, at native resolution red check mark red check mark red check mark red check mark
MAT3NECHM tavg3_3d_chm_Ne MERRA chem 3D IAU C-Grid edge mass flux, time averaged, 3D model levels, at native resolution red check mark red check mark red check mark red check mark
MAI3NECHM inst3_3d_chm_Ne MERRA chem 3D IAU edge pressure, instantaneous, 3D model levels, at native resolution red check mark red check mark red check mark red check mark

Short Name and Standard Name Legend

Both the short names and standard names adhere to conventions as described below:

 

Short Name Legend
MCTFHVGGG

Standard Name Legend
ffffN_dd_ggg_Hv

MCTFHVGGG

C: Configuration
, where C is one of:

A = Assimilation; F = Forecast; S = Simulation
ffffN_dd_ggg_Hv

ffff: Frequency Type
, where ffff is one of:

inst = Instantaneous; tavg = Time average; const = Time independent
MCTFHVGGG

T: Time Description
, where T is one of:

I = Instantaneous; T = Time Averaged; C = Time Independent
ffffN_dd_ggg_Hv

N: Frequency
, where N is one of:

1 = 1-hourly; 3 = 3-hourly; 6 = 6-hourly; M = Monthly Mean; U = Monthly Diurnal Mean; 0 = Not Applicable;
MCTFHVGGG

F: Frequency
, where F is one of:

1 = 1-hourly; 3 = 3-hourly; 6 = 6-hourly; M = Monthly Mean; U = Monthly Diurnal Mean; 0 = Not Applicable
ffffN_dd_ggg_Hv

dd: Dimensions
, where dd is one of:

2d = 2-dimensional fields only; 3d = Mix of 2- and 3-dimensional fields
MCTFHVGGG

H: Horizontal Resolution
, where H is one of:

N = Native (2/3 x 1/2 deg); F = Reduced Resolution Version of Model Grid (1.25 x 1 deg); C = Reduced Resolution (1.25 x 1.25 deg)
ffffN_dd_ggg_Hv

ggg: Group
, where ggg is one of:

ana = Direct analysis products; asm = Assimilated state variables; tdt = Tendencies of temperature; udt = Tendencies of eastward and northward wind components; qdt = Tendencies of specific humidity; odt = Tendencies of ozone; lnd = Land surface variables; flx = Surface turbulent fluxes and related quantities; mst = Moist processes; cld = Clouds; rad = Radiation; trb = Turbulence; slv = Single level; int = Vertical integrals; chm = Chemistry forcing
MCTFHVGGG

V: Vertical Location
, where V is one of:

X = Two-dimensional; P = Pressure; V = Model Layer Center; E = Model Layer Edge
ffffN_dd_ggg_Hv

H: Horizontal Resolution
, where H is one of:

N = Native (2/3 x 1/2 deg); F = Reduced Resolution Version of Model Grid (1.25 x 1 deg); C = Reduced Resolution (1.25 x 1.25 deg)
MCTFHVGGG

GGG: Group
, where GGG is one of:

ANA = Direct analysis products; ASM = Assimilated state variables; TDT = Tendencies of temperature; UDT = Tendencies of eastward and northward wind components; QDT = Tendencies of specific humidity; ODT = Tendencies of ozone; LND = Land surface variables; FLX = Surface turbulent fluxes and related quantities; MST = Moist processes; CLD = Clouds; RAD = Radiation; TRB = Turbulence; SLV = Single level; INT = Vertical integrals; CHM = Chemistry forcing
ffffN_dd_ggg_Hv

v: Vertical Location
, where v is one of:

x = Two-dimensional; p = Pressure; v = Model Layer Center; e = Model Layer Edge

 

 

 

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