ERA40 T85 Monthly Mean Surface Analysis and Surface Forecast Fields, created at NCAR

DS126.0 represents a dataset implemented and computed by NCAR's Data Support Section, and forms an essential part of efforts undertaken in late 2004, early 2005, to produce an archive of selected segments of ERA-40 on a standard transformation grid.

In this case, forty seven ERA-40 monthly mean surface and single level analysis variables were transformed from a reduced N80 Gaussian grid to a 256 by 128 regular Gaussian grid. All fields were transformed using routines from the ECMWF EMOS library, including 10 meter winds which were treated as scalars because of a lack of 10 meter spectral vorticity and divergence. A missing value occurs in the sea surface temperature and sea ice fields to mask grid points occurring over land. Fields formerly archived as whole integers, such as vegetation indices and cloud cover, occur as integers plus a fractional part in the T85 version due to interpolation.

Twenty seven ERA-40 monthly mean surface and single level 6-hour forecast variables were transformed from a reduced N80 Gaussian grid to a 256 by 128 regular Gaussian grid. Four of the variables are "instantaneous" variables, and the remaining twenty three variables are "accumulated" over the 6-hour forecast time. Divide the accumulated variables by 21600 seconds to obtain instantaneous values. (Multiplication by minus one may also be necessary to match the sign convention one is accustomed to.) All fields were transformed using routines from the ECMWF EMOS library, including three pairs of stresses which were treated as scalars because of a lack of spectral precursors.

In addition, all corresponding 00Z, 06Z, 12Z, and 18Z monthly mean surface and single level analysis variables and 6-hour forecast variables were also transformed to a T85 Gaussian grid.

All forecast variables are valid 6 hours after the forecast was initiated. Thus, 00Z 6-hour forecast evaporation is valid at 06Z. Divide the accumulated variables by 21600 seconds to obtain instantaneous values. (Multiplication by minus one may also be necessary to match the sign convention one is to.)

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) [https://www.cesm.ucar.edu/models/atm-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 [https://rda.ucar.edu/datasets/ds627.0/].

To Access Resource:

Questions? Email Resource Support Contact:

  • Dave Stepaniak
    davestep@ucar.edu
    UCAR/NCAR - Research Data Archive

Temporal Range

  • Begin:  1957-09-01T00:00:00Z
    End:  2002-08-31T18:00:00Z

Keywords

Resource Type dataset
Temporal Range Begin 1957-09-01T00:00:00Z
Temporal Range End 2002-08-31T18:00:00Z
Temporal Resolution N/A
Bounding Box North Lat 88.928
Bounding Box South Lat -88.928
Bounding Box West Long -180
Bounding Box East Long 180
Spatial Representation grid
Spatial Resolution 1.406 degree
Related Links

Related Resource #1 : ECMWF's Climate Research web site

Additional Information N/A
Asset Size 12942 MB
Legal Constraints

The data can be used for non-commercial research only.


Access Constraints We are allowed to distribute this data to US scientists, scientists visiting US organizations, and Canadian scientists affiliated with UCAR member organizations only.
Software Implementation Language N/A
Resource Support Name Dave Stepaniak
Resource Support Email davestep@ucar.edu
Resource Support Organization UCAR/NCAR - Research Data Archive
Distributor NCAR Research Data Archive
Metadata Contact Name N/A
Metadata Contact Email rdahelp@ucar.edu
Metadata Contact Organization NCAR Research Data Archive
Author 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
Publisher Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory
Publication Date 2005-05-09
Digital Object Identifier (DOI) https://doi.org/10.5065/D62805PB
Alternate Identifier ds126.0
Resource Version N/A
Topic Category climatologyMeteorologyAtmosphere
Progress completed
Metadata Date 2019-03-12T10:05:02-07:00
Metadata Record Identifier edu.ucar.rda::ds126.0
Metadata Language eng; USA
Suggested Citation 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. (2005). ERA40 T85 Monthly Mean Surface Analysis and Surface Forecast Fields, created at NCAR. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/D62805PB. Accessed 19 April 2019.

Harvest Source