List of MERRA-2 met fields

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MERRA2 is a new NASA/GMAO reanalysis product. It has a horizontal resolution of 0.5° lat x 0.625° lon x 72 vertical levels. The horizontal resolution is 2x coarser than the GMAO "forward processing" product (which we refer to as GEOS-FP). But MERRA2 uses the identical vertical grid as the GEOS-5, MERRA, and the "GEOS-FP" data products used by GEOS-Chem.

NOTE: GEOS-Chem only uses a subset of the entire MERRA2 data archive. On this page we list the MERRA2 met fields that we archive for use with GEOS-Chem.

As of August 2015, we have not finalized this list of MERRA2 met fields that we will archive for GEOS-Chem. If your research requires additional fields not listed below, please contact the GEOS-Chem Support Team.

Constant fields

Overview:

Quantities archived in this file type:
  • Time-invariant fields
    • These are mostly parameters pertaining to the horizontal grid
File naming convention:
  • MERRA2.20110101.CN.05x0625.CH.nc  (Native resolution nested CH grid)
  • MERRA2.20110101.CN.05x0625.EU.nc  (Native resolution nested EU grid)
  • MERRA2.20110101.CN.05x0625.NA.nc  (Native resolution nested NA grid)
  • MERRA2.20110101.CN.05x0625.NA.nc  (Native resolution nested SE grid)
  • MERRA2.20110101.CN.2x25.nc  (2° x 2.5° global grid)
  • MERRA2.20110101.CN.4x5.nc  (4° x 5° global grid)
[MERRA2#MERRA2 time archiving|Timestamps:]]
  • For convenience, we have assigned these data timestamp of 2015/01/01 00:00 UTC


List of MERRA2 data fields in this file type:

Field Units Collection Standard name Notes Where used in GEOS-Chem?
FRLAKE 1 const_2d_asm_Nx fraction_of_lake
  • CH4 simulation,
  • diagnostics
FRLAND 1 const_2d_asm_Nx fraction_of_land
  • Chemistry
  • Hg simulation
  • CH4 simulation
  • PBL mixing
FRLANDIC(E) 1 const_2d_asm_Nx fraction_of_land_ice
  • The original name in the GEOS-FP raw data files is FRLANDICE.
  • We shorten this to FRLANDIC for GEOS-Chem. GEOS-Chem requires 8-character met field names.
  • Hg simulation
  • CH4 simulation
  • PBL mixing
FROCEAN 1 const_2d_asm_Nx fraction_of_ocean
  • Chemistry
  • Hg simulation
  • CH4 simulation
  • Emissions
PHIS m2 s-2 const_2d_asm_Nx surface_geopotential_height
  • Kept for diagnostics

--Bob Y. (talk) 18:19, 3 August 2015 (UTC)

A1 fields

Overview:

Quantities archived in this file type:
  • Various surface fields
File naming convention:
  • MERRA2.YYYYMMDD.A1.05x0625.CH.nc  (Native resolution nested CH grid)
  • MERRA2.YYYYMMDD.A1.05x0625.EU.nc  (Native resolution nested EU grid)
  • MERRA2.YYYYMMDD.A1.05x0625.NA.nc  (Native resolution nested NA grid)
  • MERRA2.YYYYMMDD.A1.025x03125.SE.nc  (Native resolution nested SE grid)
  • MERRA2.YYYYMMDD.A1.2x25.nc  (2° x 2.5° global grid)
  • MERRA2.YYYYMMDD.A1.4x5.nc  (4° x 5° global grid)
Timestamps:
  • 00:30, 01:30, 02:30, 3:30, 4:30, 5:30 ... 23:30 GMT
    • These represent the center of the averaging period


List of MERRA2 data fields in this file type:

Field Units Collection Standard name Notes Where used in GEOS-Chem?
ALBEDO 1 tavg1_2d_rad_Nx surface_albedo
  • Dry deposition
  • Diagnostics
CLDTOT 1 tavg1_2d_rad_Nx total_cloud_area_fraction
  • For all intents and purposes, CLDTOT = the column sum of CLOUD, but at 1-hour resolution.
  • Photolysis
  • Diagnostics
EFLUX W m-2 tavg1_2d_flx_Nx total_latent_energy_flux
  • Kept for diagnostics
EVAP kg m-2 s-2 tavg1_2d_flx_Nx evaporation_from_turbulence
  • Kept for diagnostics
FRSEAICE 1 tavg1_2d_flx_Nx ice_covered_fraction_of_tile
  • We bin FRSEAICE to create the SEAICE** fields listed below.
  • Hg simulation
FRSNO 1 tavg1_2d_lnd_Nx fractional_area_of_land_snowcover
  • PBL mixing
  • Hg simulation
GRN 1 tavg1_2d_lnd_Nx greenness_fraction
  • Kept for diagnostics
GWETROOT 1 tavg1_2d_lnd_Nx root_zone_soil_wetness
  • Kept for diagnostics
GWETTOP 1 tavg1_2d_lnd_Nx surface_soil_wetness
  • CH4 simulation
  • Dust mobilization
HFLUX W m-2 tavg1_2d_flx_Nx sensible_heat_flux_from_turbulence
  • Dry deposition
LAI m2 m-2 tavg1_2d_lnd_Nx leaf_area_index
  • NOTE: GEOS-Chem uses MODIS LAI instead of the GEOS-FP LAI..
  • Kept for diagnostics
LWGNT W m-2 tavg1_2d_rad_Nx surface_net_downward_longwave_flux
  • Kept for diagnostics
LWI 1 - land_water_ice_flags
  • We derive LWI from the FRSEAICE, FROCEAN, and FRLAND fields.
  • GEOS-Chem needs LWI for backwards compatibility.
  • To determine the overall surface type in a grid box
LWTUP W m-2 tavg1_2d_rad_Nx upwelling_longwave_flux_at_toa
  • Kept for diagnostics
PARDF W m-2 tavg1_2d_lnd_Nx surface_downwelling_par_diffuse_flux
  • The name of this data field in the raw data file is "PARDFLAND".
  • Biogenic emissions
PARDR W m-2 tavg1_2d_lnd_Nx surface_downwelling_par_beam_flux
  • The name of this data field in the raw data file is "PARDRLAND".
  • Biogenic emissions
PBLH m tavg1_2d_flx_Nx planetary_boundary_layer_height
  • PBL mixing
PRECANV kg m-2 s-1 tavg1_2d_flx_Nx anvil_precipitation
  • Kept for diagnostics
PRECCON kg m-2 s-1 tavg1_2d_flx_Nx convective_precipitation
  • Soil NOx emissions
  • Wet deposition
PRECLSC kg m-2 s-1 tavg1_2d_flx_Nx nonanvil_large_scale_precipitation
  • Kept for diagnostics
PRECSNO kg m-2 s-1 tavg1_2d_flx_Nx snowfall
  • Kept for diagnostics
PRECTOT kg m-2 s-1 tavg1_2d_flx_Nx total_precipitation
  • Soil NOx emissions
  • Wet deposition
QV2M kg kg-1 tavg1_2d_slv_Nx 2-meter_specific_humidity
  • Kept for diagnostics
Q850 kg kg-1 tavg1_2d_slv_Nx specific_humidity_at_850_hPa
  • Dust mobilization
SEAICE00 1 - sea_area_ice_fraction_0-10%
  • Arctic simulations
  • Diagnostics
SEAICE10 1 - sea_area_ice_fraction_10-20%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE20 1 - sea_area_ice_fraction_20-30%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE30 1 - sea_area_ice_fraction_30-40%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE40 1 - sea_area_ice_fraction_40-50%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE50 1 - sea_area_ice_fraction_50-60%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE60 1 - sea_area_ice_fraction_60-70%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE70 1 - sea_area_ice_fraction_70-80%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE80 1 - sea_area_ice_fraction_80-90%
  • Arctic simulations
  • Planeflight diagnostics
SEAICE90 1 - sea_area_ice_fraction_90-100%
  • Arctic simulations
  • Planeflight diagnostics
SLP Pa tavg1_2d_slv_Nx sea_level_pressure
  • We keep the original units of Pa.
  • We convert to hPa when reading into GEOS-Chem.
  • Kept for diagnostics
SNODP m tavg1_2d_lnd_Nx snow_depth
  • Kept for diagnostics
SNOMAS kg m-2 tavg1_2d_lnd_Nx Total_snow_storage_land
  • Dust mobilization
  • Hg simulations
  • Dry deposition
SWGDN W m-2 tavg1_2d_rad_Nx surface_incoming_shortwave_flux
  • GEOS-Chem carries this as State_Met%RADSWG
  • Soil NOx emissions
  • Hg simulations
  • Dry deposition
SWGNT W m-2 tavg1_2d_rad_Nx Surface net downward shortwave flux
  • Kept for diagnostics
TO3 Dobsons tavg1_2d_slv_Nx total_column_ozone
  • Used as input to photolysis
TROPPT hPa tavg1_2d_slv_Nx tropopause_pressure_based_on_thermal_estimate
  • Original units of TROPPT are Pa.
  • We convert Pa -> hPa because GEOS-Chem expects hPa.
  • Used to determine tropopause height
TS K tavg1_2d_slv_Nx surface_skin_temperature
  • GEOS-Chem carries this as State_Met%TSKIN
  • CH4 simulation
  • Hg simulation
  • Sea salt emissions
T2M K tavg1_2d_slv_Nx 2-meter_air_temperature
  • GEOS-Chem carries this as State_Met%TS
  • GEOS-Chem uses T2M as a proxy for surface air temp.
  • Many locations
T10M K tavg1_2d_slv_Nx 10-meter_air_temperature
  • Dust mobilization
U10M m s-1 tavg1_2d_slv_Nx 10-meter_eastward_wind
  • Dry deposition
  • Dust mobilization
  • Emissions
  • Sea salt aerosols
  • Hg simulations
USTAR m s-1 tavg1_2d_flx_Nx surface_velocity_scale
  • Dry deposition
V10M m s-1 tavg1_2d_slv_Nx 10-meter_northward_wind
  • Dry deposition
  • Dust mobilization
  • Emissions
  • Sea salt aerosols
  • Hg simulations
Z0M m tavg1_2d_flx_Nx surface_roughness
  • Dry deposition

--Bob Y. (talk) 16:21, 3 August 2015 (UTC)

A3cld fields

Overview:

Quantities archived in this file type:
  • Cloud parameters
    • Data are 3-dimensional, stored at the midpoint of each vertical level
File naming convention:
  • MERRA2.YYYYMMDD.A3cld.05x0625.CH.nc  (Native resolution, nested CH grid)
  • MERRA2.YYYYMMDD.A3cld.05x0625.EU.nc  (Native resolution, nested EU grid)
  • MERRA2.YYYYMMDD.A3cld.05x0625.NA.nc  (Native resolution, nested NA grid)
  • MERRA2.YYYYMMDD.A3cld.05x0625.SE.nc  (Native resolution, nested SE grid)
  • MERRA2.YYYYMMDD.A3cld.2x25.nc  (2° x 2.5° global grid)
  • MERRA2.YYYYMMDD.A3cld.4x5.nc  (4° x 5° global grid)
Timestamps:
  • 01:30, 04:30, 07:30, 10:30, 13:30, 16:30, 19:30, 22:30 GMT
    • Timestamps represent the center of the 3-hour averaging period.


List of MERRA2 data fields in this file type:

Field Units Collection Standard name Notes Where used in GEOS-Chem?
CLOUD 1 tavg3_3d_cld_Nv cloud_fraction_for_radiation
  • Photolysis
  • Chemistry
OPTDEPTH 1 none in_cloud_optical_thickness
  • Photolysis
  • Chemistry
QI kg kg-1 none mass_fraction_of_cloud_ice_water
  • Chemistry
  • Aerosol microphysics
QL kg kg-1 tavg3_3d_cld_Nv mass_fration_of_cloud_liquid_water
  • Chemistry
  • Aerosol microphysics
TAUCLI 1 tavg3_3d_cld_Nv in_cloud_optical_thickness_for_ice_clouds
  • Kept for diagnostics
TAUCLW 1 tavg3_3d_cld_Nv in_cloud_optical_thickness_for_liquid_clouds
  • Kept for diagnostics

--Bob Y. (talk) 17:32, 3 August 2015 (UTC)

A3dyn fields

NOTES:

  1. These are 3-hr time-averaged fields, which will have the following filenames:
    • MERRA2.YYYYMMDD.A3dyn.05x0625.CH.nc (Native resolution, nested CH grid)
    • MERRA2.YYYYMMDD.A3dyn.05x0625.EU.nc (Native resolution, nested EU grid)
    • MERRA2.YYYYMMDD.A3dyn.05x0625.NA.nc (Native resolution, nested NA grid)
    • MERRA2.YYYYMMDD.A3dyn.05x0625.SE.nc (Native resolution, nested SE grid)
    • MERRA2.YYYYMMDD.A3dyn.2x25.nc (2° x 2.5° global grid)
    • MERRA2.YYYYMMDD.A3dyn.4x5.nc (4° x 5° global grid)
  2. All A3 fields are 3-dimensional (lon,lat,alt). Data is placed at the vertical center of each grid box.
  3. Timestamps (i.e. center of averaging period): 01:30, 04:30, 07:30, 10:30, 13:30, 16:30, 19:30, 22:30 GMT
  4. The Collection indicates the MERRA2 raw data files in which each field may be found.
    • One MERRA2 raw data file is created for each new date and time.
    • Therefore, the A3dyn data fields listed below will be contained in a single MERRA2 raw data file.


Field Units Collection Standard name Notes Where used in GEOS-Chem?
DTRAIN kg m-2 s-2 tavg3_3d_cld_Nv detraining_mass_flux
  • Cloud convection
OMEGA Pa s-1 tavg3_3d_asm_Nv vertical_pressure_velocity
  • Kept for diagnostics
RH 1 tavg3_3d_cld_Nv relative_humidity_after_moist GMAO computes RH as follows:
  • T > 273.16 K: w/r/t liquid
  • T < 253.16 K: w/r/t ice
  • 253.16 K <= T <= 273.16K: weighted avg w/r/t both liquid and ice
  • Chemistry
  • Wet deposition
  • Aerosol therm. equilib.
  • Aerosol microphysics
U m s-1 tavg3_3d_asm_Nv eastward_wind
  • Advection
V m s-1 tavg3_3d_asm_Nv northward_wind
  • Advection

--Bob Y. (talk) 17:36, 3 August 2015 (UTC)

A3mstC fields

NOTES:

  1. These are 3-hr time-averaged fields, which are stored in the following files:
    • MERRA2.YYYYMMDD.A3mstC.05x0625.CH.nc (Native resolution, nested CH grid)
    • MERRA2.YYYYMMDD.A3mstC.05x0625.EU.nc (Native resolution, nested EU grid)
    • MERRA2.YYYYMMDD.A3mstC.05x0625.NA.nc (Native resolution, nested NA grid)
    • MERRA2.YYYYMMDD.A3mstC.05x0625.SE.nc (Native resolution, nested SE grid)
    • MERRA2.YYYYMMDD.A3mstC.2x25.nc (2° x 2.5° global grid)
    • MERRA2.YYYYMMDD.A3mstC.4x5.nc (4° x 5° global grid)
  2. All A3 fields are 3-dimensional (lon,lat,alt). Data is placed at the vertical center of each grid box.
  3. Timestamps (i.e. center of averaging period): 01:30, 04:30, 07:30, 10:30, 13:30, 16:30, 19:30, 22:30 GMT
  4. The Collection indicates the GEOS-FP raw data files in which each field may be found.
    • One MERRA2 raw data file is created for each date of data.
    • Therefore, the A3mstC data fields listed below will be contained in a single MERRA2 raw data file.


Field Units Collection Standard name Notes Where used in GEOS-Chem?
DQRCU kg kg-1 s-1 tavg3_3d_mst_Nv convective_rainwater_source
  • Conv. updraft scavenging
DQRLSAN kg kg-1 s-1 tavg3_3d_mst_Nv large_scale_rainwater_source
  • Wet deposition
REEVAPCN kg kg-1 s-1 tavg3_3d_mst_Nv evap_subl_of_convective_precipitation
  • Conv. updraft scavenging
REEVAPLS(AN) kg kg-1 s-1 tavg3_3d_mst_Nv evap_subl_of_non_convective_precipitation
  • In the GEOS-FP raw data files, this field is named REEVAPLSAN.
  • In the files created for GEOS-Chem, we change the field name to REEVAPLS.
  • GEOS-Chem requires 8-character met field names for backwards compatibility.
  • Wet deposition

--Bob Y. (talk) 17:46, 3 August 2015 (UTC)

A3mstE fields

NOTES:

  1. These are 3-hr time-averaged fields, which are stored in the following files:
    • MERRA2.YYYYMMDD.A3mstE.05x0625.CH.nc  (Native resolution, nested CH grid)
    • MERRA2.YYYYMMDD.A3mstE.05x0625.EU.nc  (Native resolution, nested EU grid)
    • MERRA2.YYYYMMDD.A3mstE.05x0625.NA.nc  (Native resolution, nested NA grid)
    • MERRA2.YYYYMMDD.A3mstE.05x0625.SE.nc  (Native resolution, nested SE grid)
    • MERRA2.YYYYMMDD.A3mstE.2x25.nc  (2° x 2.5° global grid)
    • MERRA2.YYYYMMDD.A3mstE.4x5.nc  (4° x 5° global grid)
  2. All A3 fields are 3-dimensional (lon,lat,alt). Data is placed on the edges of the grid boxes.
  3. Timestamps (i.e. center of averaging period): 01:30, 04:30, 07:30, 10:30, 13:30, 16:30, 19:30, 22:30 GMT
  4. The Collection indicates the MERRA2 raw data files in which each field may be found.
    • One MERRA2 raw data file is created for new day of data
    • Therefore, the A3mstE data fields listed below will be contained within a single MERRA2 raw data file.


Field Units Collection Description Notes Where used in GEOS-Chem?
CMFMC kg m-2 s-2 tavg3_3d_mst_Ne Upward moist convective mass flux
  • Cloud convection
PFICU kg m-2 s-1 tavg3_3d_mst_Ne 3d flux of ice convective precipitation
  • Conv. updraft scavenging
PFILSAN kg m-2 s-1 tavg3_3d_mst_Ne 3d flux of ice non-convective precipitation
  • Wet deposition
PFLCU kg m-2 s-1 tavg3_3d_mst_Ne 3d flux of liquid convective precipitation
  • Conv. updraft scavenging
PFLLSAN kg m-2 s-1 tavg3_3d_mst_Ne 3d flux of liquid non-convective precipitation
  • Wet deposition

--Bob Y. 14:18, 21 October 2013 (EDT)

I3 fields

NOTES:

  1. These are 3-hr instantaneous fields, which will have the following filenames:
    • MERRA2.YYYYMMDD.I3.025x03125.CH.nc  (Native resolution, nested China grid)
    • MERRA2.YYYYMMDD.I3.025x03125.NA.nc  (Native resolution, nested North America grid)
    • MERRA@.YYYYMMDD.I3.2x25.nc  (2° x 2.5° global grid)
    • MERRA@.YYYYMMDD.I3.4x5.nc  (4° x 5° global grid)
  2. I3 fields are either 2-dimensional (lon,lat) or 3D (lon,lat,alt). 3D data is placed at the vertical centers of the grid box.
  3. Timestamps: Instantaneous values at 00:00, 03:00, 06:00, 09:00, 12:00, 15:00, 18:00, 21:00 GMT
  4. The Collection indicates the MERRA2 raw data files in which each field may be found.
  5. One MERRA2 raw data file is created for each new day of data.
    • Therefore, the I3 data fields listed below will be contained in a single data file.


Field Units Collection Standard name Notes Where used in GEOS-Chem?
PS hPa inst3_3d_asm_Nv surface_pressure
  • We keep the original units of Pa
  • We convert Pa -> hPa when reading the PS field in GEOS-Chem.
  • Advection
  • Many other locations
PV K m2 kg-1 s-1 inst3_3d_asm_Nv ertels_potential_vorticity
  • This field is labeled EPV in the GEOS-FP raw data files.
  • GEOS-Chem renames this to "PV" for backwards compatibility with older met products.
  • Kept for diagnostics
QV kg kg-1 inst3_3d_asm_Nv specific_humidity In GEOS-Chem:
  • QV at time t is converted to g/kg and saved into State_Met%SPHU1;
  • QV at time t+3hr is converted to g/kg and saved into State_Met%SPHU2;
  • QV is then interpolated to the current time.
  • Chemistry
  • Wet deposition
  • PBL mixing
T K inst3_3d_asm_Nv air_temperature In GEOS-Chem:
  • T @ time t is saved into State_Met%TMPU1;
  • T @ time t+3h is saved into State_Met%TMPU2;
  • T is then interpolated to the current time.
  • Many locations

--Bob Y. (talk) 16:27, 3 August 2015 (UTC)

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