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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

Years of Record

1957/09 to 2002/08
temporal metadataID:
oai:edu.ucar.rda:ds120.0

Formats

Timestep

Sub-daily | Monthly

Data Time Period Extended?

no, data set not being extended

Domain

Global

Spatial Resolution

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

Ocean or Land

Ocean&Land

Missing Data Flag

spatially complete

Data Assimilation Method

3DVAR

Model Resolution used to create reanlaysis

T159, 60 levels

Model Vintage (reanalysis)

2004

Earth system components and main variables

Atmosphere, Air Temperature, Geopotential Height, Water Vapor

Data Access: Please Cite data sources, following the data providers' instructions.

  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

Click the thumbnails to view larger sizes

Thumbnails

Captions
ERA40: January monthly mean potential vorticity at 300hPa.

Cite this page

National Center for Atmospheric Research Staff (Eds). Last modified 01 Mar 2016. "The Climate Data Guide: ERA40." Retrieved from https://climatedataguide.ucar.edu/climate-data/era40.

Acknowledgement of any material taken from this page is appreciated. On behalf of experts who have contributed data, advice, and/or figures, please cite their work as well.

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.

1957-09/2002-08