ERA40

ERA40

ERA 40 is a second generation reanalysis. It is the first reanalysis to directly assimilate satellite radiance data (TOVS, SSM/I, ERS and ATOVS). Cloud Motion Winds are also used. The result is better circulation over the tropics and southern hemisphere. However, unless comparing  to previous ERA-40 based results, it is recommended that the 3rd generation reanalyses, ERA-Interim or MERRA, be used for new research.

Key Strengths

Assimilates satellite radiances directly (TOVS, SSM/I, ERS and ATOVS data).

Cloud Motion Winds will be used from 1979 onwards.

Key Limitations

Tropical moisture (precipitation, total column water vapor) larger than observed from 1991 onward

Precipitation greatly exceeds evaporation

Brewer Dobson circulation is too intense; Spurious Arctic temperature trends

Please cite data sources, following the data providers' instructions
Suggested Data Citation
None
Dataset DOIs
None
Hosted Climate Index Files
None
Data Access
  1. ECMWF Portal
  2. NCAR Rsearch Data Archive listing of ERA-40 Products
  3. NCAR Research Data Archive ERA-40 2.5deg monthly mean surface data
  4. NCAR CAS Data Catalog derived mass, moisture, energy budgets
Usage Restrictions

Research only; no redistribution

Key Figures

ERA40: January monthly mean potential vorticity at 300hPa.

Other Information

Years of record
to
Metadata ID
oai:edu.ucar.rda:ds120.0
Data time period extended
No, data set not being extended
Timestep
Sub-daily, Monthly
Domain
Global
Formats:
GRIB, netCDF
Input Data
None
Vertical Levels:
None
Missing Data Flag
Spatially complete
Ocean or Land
Ocean & Land
Spatial Resolution

2.5°x2.5° / 1.125°x1.125°; 60 levels 0.1 hPA top

Model Resolution (reanalysis)

T159, 60 levels

Data Assimilation Method
3DVAR
Model Vintage (reanalysis)

2004