MERRA-2 |
A subset of the MERRA-2 (Modern-Era Retrospective analysis for Research and Applications version 2 ) reanalysis is available on ClimServ.
MERRA-2 is a NASA atmospheric reanalysis for the satellite
era using the Goddard Earth Observing System Model, Version 5 (GEOS-5)
with its Atmospheric Data Assimilation System (ADAS), version 5.12.4.
The MERRA project focuses on historical climate analyses for a broad
range of weather and climate time scales and places the NASA EOS suite
of observations in a climate context. MERRA-2 output data resemble output at frequencies higher than the 6-hourly analyses. Two-dimensional diagnostics (surface fluxes, radiation, single level meteorology for those archived at IPSL) are produced at 1-hour intervals. These data products and the 3-hourly three-dimensional atmospheric analyses are also available at the full spatial resolution (1/2 degrees latitude × 2/3 degrees longitude). The original files extracted at NASA GES DISC are in netcdf-4 format on ClimServ. Four MERRA-2 datasets are available on ClimServ: -M2I3NVASM (inst3_3d_asm_Nv): 3d,3-Hourly,Instantaneous,Model-Level,Assimilation,Assimilated Meteorological Fields (Thanks to B. Legras -LMD for his help for the 3d data access) -M2T1NXFLX (tavg1_2d_flx_Nx): MERRA IAU 2D diagnostics, surface fluxes, time averaged, single level, at native resolution -M2T1NXRAD (tavg1_2d-rad_Nx) :MERRA IAU 2D diagnostics, radiation surface and TOA, time averaged, single level, at native resolution -M2T1NXSLV (tavg1_2d_slv_Nx): MERRA IAU 2D diagnostics, single-level meteorology, time averaged, single level, at native resolution
Spatial coverageGlobal area native horizontal resolution: 1/2 degrees latitude × 2/3 degrees longitude (longitude: 540, latitude : 361) Temporal resolution
Temporal coverageThe MERRA-2period is: 1980-present; we will complete the dataset progessively on ClimServ.
LevelsModel levelsThe GEOS-5 model layers used for MERRA products are on a terrain-following hybrid sigma-p coordinate. Model-level data are output on the LM=72 layers; the indexing for the GEOS-5 vertical coordinate system in the vertical is top to bottom, i.e., layer 1 is the top layer of the atmosphere, while layer LM is adjacent to the earth’s surface.
Available parameterssurface constant parameters (2D parameters):
|
Variable Name |
Description |
Units |
---|---|---|
EFLUX | Latent heat flux (positive upward) | W m-2 |
EVAP | Surface evaporation | kg m-2s-1 |
HFLUX | Sensible heat flux (positive upward) | W m-2 |
TAUX | Eastward surface wind stress | N m-2 |
TAUY | Northward surface wind stress | N m-2 |
TAUGWX | Eastward gravity wave surface stress | N m-2 |
TAUGWY | Northward gravity wave surface stress | N m-2 |
PBLH | Planetary boundary layer height | m |
DISPH | Displacement height | m |
BSTAR | Surface buoyancy scale | m s-1 |
USTAR | Surface velocity scale | m s-1 |
TSTAR | Surface temperature scale | K |
QSTAR | Surface humidity scale | kg kg-1 |
RI | Surface Richardson number | nondimensional |
Z0H | Roughness length, sensible heat | m |
Z0M | Roughness length, momentum | m |
HLML | Height of center of lowest model layer | m |
TLML | Temperature of lowest model layer | K |
QLML | Specific humidity of lowest model layer | kg kg-1 |
ULML | Eastward wind of lowest model layer | m s-1 |
VLML | Northward wind of lowest model layer | m s-1 |
RHOA | Surface air density | kg m-3 |
CDH | Surface exchange coefficient for heat | kg m-2s-1 |
CDQ | Surface exchange coefficient for moisture | kg m-2s-1 |
CDM | Surface exchange coefficient for momentum | kg m-2s-1 |
CN | Surface neutral drag coefficient | nondimensional |
TSH | Effective turbulence skin temperature | K |
QSH | Effective turbulence skin humidity | kg kg-1 |
FRSEAICE | Fraction of sea-ice | fraction |
PRECANV | Surface precipitation flux from anvils | kg m-2s-1 |
PRECCON | Surface precipitation flux from convection | kg m-2s-1 |
PRECLSC | Surface precipitation flux from large-scale | kg m-2s-1 |
PRECSNO | Surface snowfall flux | kg m-2s-1 |
PRECTOT | Total surface precipitation flux | kg m-2s-1 |
PGENTOT | Total generation of precipitation | kg m-2s-1 |
PREVTOT | Total re-evaporation of precipitation | kg m-2s-1 |
The parameters in blue are those extracted from the original M2T1NXRAD dataset full list below:
Variable Name |
Description |
Units |
---|---|---|
EMIS | Surface emissivity | fraction |
TS | Surface skin temperature | K |
ALBEDO | Surface albedo | fraction |
ALBNIRDF | Diffuse beam NIR surface albedo | fraction |
ALBNIRDR | Direct beam NIR surface albedo | fraction |
ALBVISDF | Diffuse beam VIS-UV surface albedo | fraction |
ALBVISDR | Direct beam VIS-UV surface albedo | fraction |
LWGEM | Emitted longwave at the surface | W m-2 |
LWGAB | Absorbed longwave at the surface | W m-2 |
LWGABCLR | Absorbed longwave at the surface with no clouds | W m-2 |
LWGABCLRCLN | Absorbed longwave at the surface with no clouds or aerosol | W m-2 |
LWGNT | Net downward longwave flux at the surface | W m-2 |
LWGNTCLR | Net downward longwave flux at the surface for cloud-free sky | W m-2 |
LWGNTCLRCLN | Net downward longwave flux at the surface for clear sky | W m-2 |
LWTUP | Upward longwave flux at top of atmosphere (TOA) | W m-2 |
LWTUPCLR | Upward longwave flux at TOA assuming clear sky | W m-2 |
LWTUPCLRCLN | Upward longwave flux at TOA assuming clear clean sky | W m-2 |
SWTDN | TOA incident shortwave flux | W m-2 |
SWGDN | Surface incident shortwave flux | W m-2 |
SWGDNCLR | Surface incident shortwave flux assuming clear sky | W m-2 |
SWGNT | Surface net downward shortwave flux | W m-2 |
SWGNTCLR | Surface net downward shortwave flux assuming clear sky | W m-2 |
SWGNTCLN | Surface net downward shortwave flux assuming clean sky | W m-2 |
SWGNTCLRCLN | Surface net downward shortwave flux assuming clear clean sky | W m-2 |
SWTNT | TOA net downward shortwave flux | W m-2 |
SWTNTCLR | TOA net downward shortwave flux assuming clear sky | W m-2 |
SWTNTCLN | TOA net downward shortwave flux assuming clean sky | W m-2 |
SWTNTCLRCLN | TOA net downward shortwave flux assuming clear clean sky | W m-2 |
TAUHGH | Optical thickness of high clouds | dimensionless |
TAULOW | Optical thickness of low clouds | dimensionless |
TAUMID | Optical thickness of mid-level clouds | dimensionless |
TAUTOT | Optical thickness of all clouds | dimensionless |
CLDHGH | High-level (above 400 hPa) cloud fraction | fraction |
CLDLOW | Low-level (1000-700 hPa) cloud fraction | fraction |
CLDMID | Mid-level (700-400 hPa) cloud fraction | fraction |
CLDTOT | Total cloud fraction | fraction |
The parameters in blue are those extracted from the original M2T1NXSLV dataset full list below:
Variable Name |
Description |
Units |
---|---|---|
SLP | Sea level pressure | Pa |
PS | Time averaged surface pressure | Pa |
U850 | Eastward wind at 850 hPa | m s-1 |
U500 | Eastward wind at 500 hPa | m s-1 |
U250 | Eastward wind at 250 hPa | m s-1 |
V850 | Northward wind at 850 hPa | m s-1 |
V500 | Northward wind at 500 hPa | m s-1 |
V250 | Northward wind at 250 hPa | m s-1 |
T850 | Temperature at 850 hPa | K |
T500 | Temperature at 500 hPa | K |
T250 | Temperature at 250 hPa | K |
Q850 | Specific humidity at 850 hPa | kg kg-1 |
Q500 | Specific humidity at 500 hPa | kg kg-1 |
Q250 | Specific humidity at 250 hPa | kg kg-1 |
H850 | Height at 850 hPa | m |
H500 | Height at 500 hPa | m |
H250 | Height at 250 hPa | m |
OMEGA500 | Vertical pressure velocity at 500 hPa | Pa s-1 |
U10M | Eastward wind at 10 m above displacement height | m s-1 |
U2M | Eastward wind at 2 m above the displacement height | m s-1 |
U50M | Eastward wind at 50 m above surface | m s-1 |
V10M | Northward wind at 10 m above the displacement height | m s-1 |
V2M | Northward wind at 2 m above the displacement height | m s-1 |
V50M | Northward wind at 50 m above surface | m s-1 |
T10M | Temperature at 10 m above the displacement height | K |
T2M | Temperature at 2 m above the displacement height | K |
QV10M | Specific humidity at 10 m above the displacement height | kg kg-1 |
QV2M | Specific humidity at 2 m above the displacement height | kg kg-1 |
TS | Surface skin temperature | K |
DISPH | Displacement height | m |
TROPPV | PV based tropopause pressure | Pa |
TROPPT | T based tropopause pressure | Pa |
TROPPB | blended tropopause pressure | Pa |
TROPT | Tropopause temperature | K |
TROPQ | Tropopause specific humidity | kg kg-1 |
CLDPRS | Cloud-top pressure | Pa |
CLDTMP | Cloud-top temperature | K |
The parameters in blue are those extracted from the original M2I3NVASM dataset full list:
Variable Name |
Dims |
Description |
Units |
---|---|---|---|
PS | 2D | Surface pressure | Pa |
OMEGA |
3D |
Vertical pressure velocity |
Pa s-1 |
T | 3D | Air temperature | K |
U | 3D | Eastward wind component | m s-1 |
V | 3D | Northward wind component | m s-1 |
QV | 3D | Specific humidity | kg kg-1 |
QI | 3D | mass fraction of cloud ice water | kg kg-1 |
QL | 3D | mass fraction of cloud liquid water | kg kg-1 |
The access to this dataset is restricted to the members of IPSL.
You can access data by several ways :
The data files are in the netCDF-4 format, classical model and are compatible with the CF convention. It defines the meaning of attributes, the units, the coordinate variables.
The files are organized by variable, by day.
- FFF: format (NC)
- RESOL: is the resolution: native_resol
- XXX: is the temporal resolution (daily)
- LL: LL is the level type (SF for surface, ML for Model Level)
- YYYY: year
- MM: month
- NAME: is the netcdf parameter name (see parameters lists)
- MERRAID: MERRA-2 dataset name ID
- YYYYMMDD: date
http://gmao.gsfc.nasa.gov/research/MERRA-2/
http://goldsmr4.sci.gsfc.nasa.gov/opendap/MERRA2/
http://disc.sci.gsfc.nasa.gov/uui/search/%22MERRA-2%22
http://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/docs/
File specification: http://gmao.gsfc.nasa.gov/pubs/docs/Bosilovich785.pdf
MERRA pages on the Climate data guide web site (from NCAR): https://climatedataguide.ucar.edu/reanalysis/nasa-merra
Web site for reanalysis intercomparisons: http://www.reanalyses.org
To cite the data in publications:
Global Modeling and Assimilation Office (GMAO) (2015),MERRA-2 inst1_2d_asm_Nx: 2d,3-Hourly,Instantaneous,Single-Level,Assimilation,Single-Level Diagnostics,version 5.12.4, Greenbelt, MD, USA:Goddard Space Flight Center Distributed Active Archive Center (GSFC DAAC), Accessed Enter User Data Access Date at doi:10.5067/3Z173KIE2TPD