The Modern Era Retrospective-Analysis for Research and Applications (MERRA) is a NASA reanalysis integrating satellite observations using a major new version of the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5).
MERRA focuses on historical analyses of the hydrological cycle on a broad range of weather and climate time scales covering the modern satellite era from 1979 to present.
The state-of-the-art GEOS-5 data assimilation system includes many modern observing systems (such as EOS) in a climate framework Specifically, the GEOS-DAS Version 5 implements Incremental Analysis Updates (IAU) to slowly adjust the model states toward the observed state.

MERRA2 is produced with the GMAO/GEOS-5 Data Assimilation System Version 5.12.4 and its native resolution is 0.5° x 0.625° x 72 hybrid sigma/pressure levels. Hourly data intervals are used for two-dimensional products, while 3-hourly intervals are used for three-dimensional products. These may be on the model’s native 72-layer vertical grid or at 42 pressure surfaces extending to 0.1 hPa.
MERRA2 spans from 1979 to present (with about 5 months lag).

The 42 pressure levels are: 1000, 975, 950, 925, 900, 875, 850, 825, 800, 775, 750, 725, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150,100, 70, 50, 40, 30, 20,10, 7, 5, 4, 3, 2, 1,0.7, 0.5, 0.4, 0.3, 0.1 hPa
The 72 native grid levels are:

Information retrieved from NCAR climate re-analysis guide and
GEOS-CHEM MERRA2 wiki. The data was downloaded from the GES DISC data store where
information on all the MERRA-2 products is available.

MERRA2 on raijin


We are hosting a copy of some of the MERRA2 products on raijin in new "Global Observations and Re-analysis Datasets" group rr7, in collaboration with CAWCR.
The data is available in /g/data1/rr7/MERRA2/raw/<MERRA-product>/<year>/<files>
Filenames are <runid>.<collection>.<timestamp>.nc4

Last update on 24th of October 2016: updated to September 2016 included.

We started with the following products, that will be regularly updated:
  • tavg1_2d_rad_Nx
    • MERRA 2D,1-hourly,time-averaged,single-level,assimilation,radiation diagnostics
    • /M2T1NXRAD.5.12.4/yyyy/mm/MERRA2_100.tavg1_2d_rad_Nx.yyyymmdd.nc4
    • resolution: lat/lon - 0.5 /0.625 degrees Timestep: 1 hourly
    • doi: 10.5067/Q9QMY5PBNV1T
    • file size: 209 Mb
  • tavg1_2d_flx_Nx
    • MERRA2 2D 1-hourly,time-averaged,single-level,assimilation,surface flux diagnostics
    • /M2T1NXFLX.5.12.4/yyyy/mm/MERRA2_100.tavg1_2d_flx_Nx.yyyymmdd.nc4
    • resolution: lat/lon - 0.5 /0.625 degrees Timestep: 1 hourly
    • doi: 10.5067/7MCPBJ41Y0K6
    • file size: 380 Mb
  • tavg1_2d_int_Nx
    • MERRA 2D ,1-hourly,time-averaged,single-level,assimilation,vertically integrated diagnostics
    • /M2T1NXINT.5.12.4/yyyy/mm/MERRA2_100.tavg1_2d_int_Nx.yyyymmdd.nc4
    • resolution: lat/lon - 0.5 /0.625 degrees Timestep: 1 hourly
    • doi: 10.5067/Q5GVUVUIVGO7
    • file size: 1.3 Gb
  • inst6d_3d_ana_Np
    • MERRA 3D,6-hourly,instantaneous,pressure-level,analysis,analyzed meteorological fields
    • /M2I1NPANA.5.12.4/yyyy/mm/MERRA2_100.inst6_3d_ana_Np.yyyymmdd.nc4
    • resolution: lat/lon - 0.5 /0.625 degrees Timestep: 6 hourly Levels: 42
    • doi: 10.5067/A7S6XP56VZWS
    • file size: 511 Mb
  • tavg1_2d_slv_Nx
    • MERRA 2D,1-hourly,Time-Averaged,Single-Level,Assimilation,Single-Level Diagnostics
    • /M2T1NXSLV.5.12.4/yyyy/mm/MERRA2_100.tavg1_2d_slv_Nx.yyyymmdd.nc4
    • resolution: lat/lon - 0.5 /0.625 degrees Timestep: 1 hourly
    • doi: 10.5067/VJAFPLI1CSIV
    • file size: 400 Mb
  • inst3d_3d_asm_Np
    • MERRA 3D,3-hourly,Instantaneous,Pressure-Level,Assimilation,Assimilated Meteorological Fields
    • /M2I3NPASM.5.12.4/yyyy/mm/MERRA2_100.inst3_3d_asm_Np.yyyymmdd.nc4
    • resolution: lat/lon - 0.5 /0.625 degrees Timestep: 3 hourly Levels: 42
    • doi: 10.5067/QBZ6MG944HW0
    • file size: 1.2 Gb
  • List of variables available for each product