ERA5.1: Corrections to ERA5 Stratospheric Temperature 2000-2006

In ECMWF Technical Memo 859 released in January 2020, Simmons and his coauthors report that "the ERA5 analyses of lower stratospheric temperature exhibit a pronounced cold bias for the years 2000 to 2006. This is due to specifying background error covariances for the data assimilation that were inappropriate prior to availability during 2006 of GNSS radio occultation data in sufficient numbers to constrain a cold bias of the assimilating ERA5 model. A new set of analyses, termed ERA5.1, has thus been produced for the period from 2000 to 2006 using the background error covariances that were used to produce the ERA5 analyses for the years 1979 to 1999. ERA5.1 also includes the more restrictive ensemble assimilation of SBUV ozone data that was used in production of ERA5 for 1979 to 1999."

"ERA5.1 provides analyses with better global-mean temperatures in the
stratosphere and uppermost troposphere than provided by ERA5. ERA5.1 stands up
well in comparison with ERA-Interim and other reanalyses in the lower stratosphere,
although there are also lower-stratospheric temperature differences between ERA5
and other reanalyses in the 1980s and 1990s. These are due in part to differences
in radiosonde temperature bias adjustment. The pronounced near-tropopause cold bias
of ERA5 from 2000 to 2006 has implications for the representation of stratospheric
humidity, for which ERA5.1 performs better, though by no means perfectly.
ERA5.1 does not exhibit the  spuriously high values of ozone that occur close
to the South Pole in the polar nights of 2003 and 2004 in the ERA5 analyses.
Synoptic evolution in the extratropical stratosphere is seen to be
very similar in two cases involving splitting of the stratospheric polar vortex and
secondary vortex formation by dynamical instability. The ERA5.1 representation of
the QBO agrees slightly better with radiosonde wind data than that of ERA5.
The dataset formed by merging ERA5.1 with ERA5 is generally more homogeneous
over time than ERA5 alone. It nevertheless is problematic for global-mean upper
stratospheric temperature for all but the most recent ten or so years."

"ERA5.1 is very close to ERA5 in the lower and middle troposphere."

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Temporal Range

  • Begin:  2000-01-01T0000+00
    End:  2006-12-31T2300+00

Keywords

Resource Type dataset
Temporal Range Begin 2000-01-01T0000+00
Temporal Range End 2006-12-31T2300+00
Temporal Resolution N/A
Bounding Box North Lat 90.0
Bounding Box South Lat -90.0
Bounding Box West Long -180.0
Bounding Box East Long 180.0
Spatial Representation grid
Spatial Resolution 0.25 degree
Related Links

Related Resource #1 : ERA5
Additional Information N/A
Resource Format WMO GRIB1
NetCDF4
Standardized Resource Format NetCDF
GRIB
Asset Size 175537470.498 MB
Legal Constraints

Creative Commons Attribution 4.0 International License
Access Constraints None
Software Implementation Language N/A

Resource Support Name N/A
Resource Support Email datahelp@ucar.edu
Resource Support Organization N/A
Distributor NSF NCAR Geoscience Data Exchange
Metadata Contact Name N/A
Metadata Contact Email datahelp@ucar.edu
Metadata Contact Organization NSF NCAR Geoscience Data Exchange

Author European Centre for Medium-Range Weather Forecasts
Publisher NSF National Center for Atmospheric Research
Publication Date 2020-06-12
Digital Object Identifier (DOI) https://doi.org/10.5065/CBTN-V814
Alternate Identifier d633002
Resource Version N/A
Topic Category climatologyMeteorologyAtmosphere
Progress completed
Metadata Date 2025-10-09T01:28:17Z
Metadata Record Identifier edu.ucar.gdex::d633002
Metadata Language eng; USA
Suggested Citation European Centre for Medium-Range Weather Forecasts. (2020). ERA5.1: Corrections to ERA5 Stratospheric Temperature 2000-2006. NSF National Center for Atmospheric Research. https://doi.org/10.5065/CBTN-V814. Accessed 24 October 2025.

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