List of MERRA-2 met fields

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MERRA-2 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 MERRA-2 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 MERRA-2 data archive. On this page we list the MERRA-2 met fields that we archive for use with GEOS-Chem.

As of August 2015, we have not finalized this list of MERRA-2 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:
  • MERRA2.20150101.CN.05x0625.CH.nc  (Native resolution nested CH grid)
  • MERRA2.20150101.CN.05x0625.EU.nc  (Native resolution nested EU grid)
  • MERRA2.20150101.CN.05x0625.NA.nc  (Native resolution nested NA grid)
  • MERRA2.20150101.CN.05x0625.NA.nc  (Native resolution nested SE grid)
  • MERRA2.20150101.CN.2x25.nc  (2° x 2.5° global grid)
  • MERRA2.20150101.CN.4x5.nc  (4° x 5° global grid)
Timestamps:
  • For convenience, we have assigned these data timestamp of 2015/01/01 00:00 UTC


List of MERRA-2 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 1-hour averaging period


List of MERRA-2 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 MERRA-2 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

Overview:

Quantities archived in this file type:
  • Dynamical fields (e.g. winds, relative humidity, detrainment fluxes)
    • Data are 3-dimensional, stored at the midpoint of each vertical level
File naming convention:
  • 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)
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 MERRA-2 data fields in this file type:

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

Overview:

Quantities archived in this file type:
  • Precipitation and sublimation fields
    • Data are 3-dimensional, stored at the midpoint of each vertical level
File naming convention:
  • 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)
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 MERRA-2 data fields in this file type:

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

Overview:

Quantities archived in this file type:
  • Precipitation and convection fields
    • Data are 3-dimensional, stored at the edges of each vertical level
File naming convention:
  • 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)
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 MERRA-2 data fields in this file type:

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. (talk) 18:52, 3 August 2015 (UTC)

I3 fields

Overview:

Quantities archived in this file type:
  • Pressure, temperature, humidity
    • Data are 3-dimensional, stored at the midpoint of each vertical level
File naming convention:
  • MERRA2.YYYYMMDD.I3.05x0625.CH.nc  (Native resolution, nested China grid)
  • MERRA2.YYYYMMDD.I3.05x0625.EU.nc  (Native resolution, nested Europe grid)
  • MERRA2.YYYYMMDD.I3.05x0625.NA.nc  (Native resolution, nested North America grid)
  • MERRA2.YYYYMMDD.I3.05x0625.SE.nc  (Native resolution, nested SE Asia grid)
  • MERRA2.YYYYMMDD.I3.2x25.nc  (2° x 2.5° global grid)
  • MERRA2.YYYYMMDD.I3.4x5.nc  (4° x 5° global grid)
Timestamps:
  • 00:00, 03:00, 06:00, 09:00, 12:00, 15:00, 18:00, 21:00 GMT
    • Timestamps represent instantaneous ("snapshot") values every 3 hours.


List of MERRA-2 data fields in this file type:

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) 18:56, 3 August 2015 (UTC)