13 November 2020

ERA5 back extension 1950-1978 (Preliminary version)

ECMWF has announced that the Copernicus Climate Change Service (C3S) has begun the release of the ERA5 back extension data covering the period 1950-1978 on the Climate Data Store (CDS).

Although in many other respects the quality of this dataset is quite satisfactory, the current back extension appears to suffer from tropical cyclones that are sometimes unrealistically intense. This is in contrast with the ERA5 product from 1979 onwards (also available from the CDS and RDA-ds633.0). For more details see the article, ERA5 back extension 1950-1978 (Preliminary version): tropical cyclones are too intense.

For this reason the current release of the back extension is preliminary.

It is therefore available from separate CDS catalogue entries (hourly, monthly, single level and pressure levels), and RDA dataset ds633.4 ERA5 back extension 1950-1978 (Preliminary version). Around the end of 2021 an updated version of the back extension is to be made available which will be added to the ERA5 catalogue entries that currently reach back to 1979. After an overlap period (the duration of which is not yet decided), the preliminary back extension will be deprecated.

The full back extension preliminary dataset is expected to be made available near the end of 2020/early 2021.

22 October 2020

Service Level Expectations for RDA Subset Request Processing

Due to resource constraints, it may take up to 48 hours for an RDA subset/format conversion request to process to completion.  Jobs may hold in status "Q" for 24 hours or more until processing resources become available.

18 September 2020

JMA JRA55 Near Real-Time Datasets

The RDA now hosts two new JRA55 near real-time datasets. For 3-hourly and 6-hourly analysis and forecast data that is auto-updated daily please see ds628.8

JRA-55: Japanese 55-year Reanalysis, Near Real-Time Data

The analysis data has 2 day delay, the forecast data 2 or 3 day delay depending on group.

For monthly mean analysis and forecast data please see ds628.9

JRA-55: Japanese 55-year Reanalysis, Near Real-Time Data -- Monthly Means and Variances

The monthly mean data for a given month is updated within the first few days of the following month. Both of these datasets represent rotating non-permanent archives. The lifetime of the 3-hourly and 6-hourly data is 7 months. The lifetime of the monthly mean data is to be determined. However, all near real-time JRA55 data is archived into their "formal" counterparts ds628.0:

JRA-55: Japanese 55-year Reanalysis, Daily 3-Hourly and 6-Hourly Data

and ds628.1

JRA-55: Japanese 55-year Reanalysis, Monthly Means and Variances

as soon as possible.

31 August 2020

ECMWF Operational and Reanalysis Datasets now accessible for all registers RDA users.

Due to a recent change in ECMWF's data access and usage policies, all registered RDA users can now access any ECMWF dataset hosted in the RDA.  This includes the both the ECMWF operational and ECMWF reanalysis datasets maintained in the RDA.  Please review ECMWF's specific "Terms of Use" for the dataset that you are interested in accessing for further details.  This can be accessed in the "Usage Restrictions" section of the dataset description page.

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