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ERA40 T85 Analysis Fields on Pressure Surfaces, created at NCAR

| DOI: 10.5065/D69S1P26

This historical dataset is recommended for ancillary use only and not as a primary research dataset. It has likely been superseded by a newer, improved dataset.


The ECMWF Re-Analysis (ERA40) is a global atmospheric analysis of many conventional observations and satellite data streams for the period September 1957 to August 2002. There are numerous data products that are separated into dataset series based on resolution, vertical coordinate reference, and likely research applications.

DS124.1 represents a new data set implemented and computed by NCAR's Data Support Section, and forms a substantial part of ongoing efforts to produce an archive of selected segments of ERA-40 on a standard transformation grid. In this case, ERA-40 upper air variables on 23 pressure levels have been transformed from either spherical harmonics (geopotential, temperature, vertical pressure velocity, vorticity, divergence, relative humidity), or a reduced N80 Gaussian grid (potential vorticity, specific humidity, ozone mass mixing ratio), to a 256 by 128 regular Gaussian grid at T85 spectral truncation. In addition, horizontal wind components have been derived from spectral vorticity and divergence and also archived on a T85 Gaussian grid. All fields are available four times per day (00,06,12 and 18 UTC). All scalar fields have been transformed using routines from the ECMWF EMOS library, whereas the horizontal winds have been obtained using NCAR's SPHEREPACK library. The choice of a T85 Gaussian grid was based on considerations of limiting the volume of new data generated to a moderate level, and to match the horizontal resolution of the Community Atmosphere Model (CAM) component of NCAR's Community Climate System Model (CCSM).

The ERA-Interim data from ECMWF is an update to the ERA-40 project. The ERA-Interim data starts in 1989 and has a higher horizontal resolution (T255, N128 nominally 0.703125 degrees) than the ERA-40 data (T159, N80 nominally 1.125 degrees). ERA-Interim is based on a more current model than ERA-40 and uses 4DVAR (as opposed to 3DVAR in ERA-40). ECMWF will continue to run the ERA-Interim model in near real time through at least 2010, and possibly longer. This data is available in ds627.0.

Temporal Range:
1957-09-01 00:00 +0000 to 2002-08-31 18:00 +0000
Usage Restrictions:

Downloading/Accessing data from this dataset implies acceptance of ECMWF's Terms of Use

Convergence Humidity Tropospheric Ozone Upper Air Temperature
Upper Level Winds Vertical Wind Velocity/Speed Vorticity
GRIB parameter table: HTML | XML
Vertical Levels:
See the detailed metadata for level information.
Data Types:
Spatial Coverage:
Longitude Range: Westernmost=180W Easternmost=180E
Latitude Range: Southernmost=88.928S Northernmost=88.928N Detailed coverage information
Data Contributors:
Research Data Archive, Computational and Information Systems Laboratory, National Center for Atmospheric Research, University Corporation for Atmospheric Research
European Centre for Medium-Range Weather Forecasts
Related Resources:
Total Volume:
1.09 TB
Data Formats:
Related RDA Datasets:
ERA-Interim Project
More Details:
View a more detailed summary of the data, including specific date ranges and locations by parameter
Metadata Record:
Data License:
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