15 June 2020

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

CISL DECS/RDA is producing a 0.25° 1440x721 regular longitude-latitude grid version of ERA5.1 in GRIB 1 and netCDF4/HDF5 format. As far as we know, ECMWF will not be making ERA5.1 available to the general public via the Copernicus Climate Data Store (CDS). Please refer to

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

and especially the 2020 memo by Adrian Simmons and ECMWF colleagues quoted here:

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."

08 May 2020

ERA5 GRIB Web Files Availability

All ERA5 GRIB files are now available as glade files and online web files via ds633.0

ERA5 Reanalysis (0.25 Degree Latitude-Longitude Grid)

The following table summarizes year-by-year status.

ERA5 GRIB Web Files Availability. This table is updated frequently. IP is "in progress".

YearGlade FilesWhole File Web DownloadSubsetting

31 March 2020

ISPD version 4 subsetting

Regional and temporal subsetting is now available in RDA dataset ds132.2 for the International Surface Pressure Databank version 4 (ISPDv4).  This service is recommended for users who are interested in a local region and time period of interest without resorting to downloading a large volume of data files from the ISPDv4 archive.

To request a subset, go to the ds132.2 Data Access tab, then select "Get a subset".  Enter your time period and region of interest, then follow the instructions to submit your data request.  After submitting your request, the request will be processed on the NCAR computing system and we will send you an email notification with a download link when your data are ready.

Users can also browse an interactive map displaying ISPDv4 observation locations by using the Interactive Station Viewer tool.  Filters can be applied to display observation locations by time period, location, and observation type.

04 March 2020

ERA5 Modes of Interannual Variability

ds633.3: ERA5 Modes of Interannual Variability

represents a suite of climate diagnostics for 56 variables relating to the interannual variability of ECMWF ERA5 monthly mean data. Basic fields for each variable include a monthly mean climatology and standard deviation, corresponding anomalies spanning 40 or more years of data, empirical orthogonal functions (EOFs), principal component (PC) time series, percent variance explained by each EOF, and an estimate of the standard error of the percent variance explained. Dominant modes of variability include El Nino Southern Oscillation (ENSO) in sea surface temperature, and the Antarctic Oscillation (AO) and North Atlantic Oscillation (NAO) in surface pressure. Separate analyses are performed for the entire globe, northern hemisphere only, and southern hemisphere only. There is sufficient information to further explore lagged correlations, teleconnections, and more advanced statistical techniques. Preparation and calculation of this dataset is performed by CISL DECS at NCAR. Code used for computing EOFs of scalar fields can be found at


03 March 2020

RDA External Application API Update

RDA External Application API Update

The RDA has introduced an update to the RDA External Applications API. The REST API will now return JSON encoded responses to queries, which should improve interactivity and allow for more robust error handling.

In addition to the updated HTTPS responses, an updated version of the rdams-client.py script has been released. This new python client can be used as a command line tool (as in the past) or as an imported python module to interact with the response objects directly.

A Jupyter Notebook that outlines how to use the module programmatically can be found here:


The complete API documentation can be found here: REST API and JSON Responses documentation

To demonstrate just one use case,
If you were to do an HTTPS GET call of the following url:
GET https://rda.ucar.edu/json_apps/paramsummary/ds083.2

An Example Response

This response could then be programmatically parsed to find only variables that had a certain unit, or those that were in GRIB2 format.
   "status": "ok",
   "request_duration": "0.173482 seconds",
   "code": 200,
   "messages": [],
   "result": {
      "dsid": "083.2",
      "subsetting_available": true,
      "data": [
            "native_format": "WMO_GRIB2",
            "param": "VIS",
            "GCMD_uuid": "9337898d-68dc-43d7-93a9-6afdb4ab1784",
            "units": "m",
            "param_description": "Visibility"
            "param_description": "Categorical snow (yes=1; no=0)",
            "native_format": "WMO_GRIB2",
            "param": "CSNOW"
            "native_format": "WMO_GRIB2",
            "param": "PEVPR",
            "standard_name": "potential_water_evaporation_flux",
            "GCMD_uuid": "b68ab978-6db6-49ee-84e2-5f37b461a998",
            "units": "W m^-2",
            "param_description": "Potential evaporation rate"
            "native_format": "WMO_GRIB2",
            "param": "T CDC",
            "GCMD_uuid": "acb52274-6c0d-4241-a979-3fa3efca6702",
            "units": "%",
            "param_description": "Total cloud cover"


            "native_format": "WMO_GRIB1",
            "param": "ABSV",
            "standard_name": "atmosphere_absolute_vorticity",
            "ISO_TopicCategoryCode": "climatologyMeteorologyAtmosphere",
            "units": "s^-1",
            "GCMD_uuid": "858a80ff-5aa4-4590-b2e2-e88a802a6ee4",
            "param_description": "Absolute vorticity"
            "native_format": "WMO_GRIB1",
            "param": "VVEL",
            "standard_name": "lagrangian_tendency_of_air_pressure",
            "ISO_TopicCategoryCode": "climatologyMeteorologyAtmosphere",
            "units": "Pa s^-1",
            "GCMD_uuid": "841a7ac7-5981-4e93-895f-1b57c3d892a0",
            "param_description": "Vertical velocity (pressure)"
   "request_end": "2020-03-03T10:52:38.637789",
   "request_start": "2020-03-03T10:52:38.464307"

29 January 2020

Issue with tropical cyclone analysis in JRA-55

JMA (Japan Meteorological Agency) has announced that some tropical cyclones occurring over the Northeast Pacific and the North Atlantic from 1959 to 1987 were erroneously represented as anti-cyclonic vortices in the Japanese 55-year Reanalysis (JRA-55) dataset. A detailed report by JMA with lists of erroneous anti-cyclonic vortices can be found in the RDA documentation for JRA-55. Please refer to the January 2020 entries at:

JRA-55 Documentation

27 January 2020

NOAA-CIRES-DOE Twentieth Century Reanalysis Version 3 Now Available

20CRv3 gridded reanalysis spanning 1836-2015 in netCDF4/HDF5 format are available for download and subsetting via
There are 113 3-hourly analysis, 19 6-hourly analysis, and 71 3-hourly first guess parameters which include 52 vertical levels. Each parameter is separated into a yearly time series. 

12 November 2019

ERA5 0.25 degree monthly mean data available

ERA5 0.25° gridded monthly means spanning 1979-2018 in netCDF4/HDF5 format are available for download and subsetting via

ERA5 Reanalysis (Monthly Mean 0.25 Degree Latitude-Longitude Grid)

There are 227 parameters in 6 groups including pressure level and surface analysis, and surface forecast data. Data prior to 1979 will be added pending public release by ECMWF, and similarly this dataset will be updated post-2018.

28 October 2019

ERA-Interim updated through August 2019

ERA-Interim in the RDA has been updated through August 2019 (the final year and month):

ERA-Interim Project

Further production of ERA-Interim has been ceased by ECMWF. The primary ECMWF reanalysis has now shifted to

ERA5 Reanalysis (0.25 Degree Latitude-Longitude Grid)

spanning January 1979 to July 2019 which is being updated on a monthly basis. ERA5 prior to 1979 (1950-1978) will be made available pending public release by ECMWF.

04 October 2019

Changes to NCAR RDA Maintained ERA5 datasets

The currently available, full time-series of ERA5 has been published under ds633.0 -ERA5 Reanalysis (0.25 Degree Latitude-Longitude Grid) https://rda.ucar.edu/datasets/ds633.0/#!description.  Data are now available from 1979 to the present in ds633.0, and it will continue to be extended in time. Data from 1950 to 1978 will be added once they become available in the Copernicus Climate Data Store. Processing and archiving of data to ds630.0 -ERA5 Reanalysis, https://rda.ucar.edu/datasets/ds630.0/#!description has been discontinued and the web access has been removed as of Oct 3, 2019.  Additionally, NCAR HPC users will no longer be able to access ds630.0 from the glade file system, as the data have been purged to free up storage space.  NCAR HPC users should now access ERA5 data from the ds633.0 dataset directory

For background, processing and publication of data to ds630.0 was stopped in April, 2019, due to the length of time it was taking to update that dataset.  It was estimated that it would take around 6-7 years to download, process, and archive data in ds630.0 using legacy strategies, versus around 1 year to download, process, and archive the full time series (1950 - present)  of the 0.25x0.25 gridded data staged online in the Copernicus Climate Data Store.