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Version

Date

Description of modifications

Chapters / Sections

1.0

18/07/2018

First draft

Whole document

2.0

10/06/2019

  • Extended information about adjustments to data fields
  • Addition of ERA5 to dataset
  • Update to ERA- Interim fields from v1. to v2., with differences described

Whole document

3.0

28/11/2019

- Update of ERA5 surface air temperature fields from v01 to v02 and of 12-month running mean statistics to v02 (ERA5) and v03 (ERA-Interim) with differences
described

GRIB codes and version numbers, p. 10-11.

4.0

01/03/2021

- Introduction of additional reference period (1991-
2020).


5.002/02/2022Table 3 updated (December column)Known Issues
6.016/05/2022Formatting of documentation updated
7.022/12/2022new known issue added (Incomplete retrieval of ERA5 during DHS move affecting RH used in the Climate bulletin)Known issues


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table1
table1
Table 1: Main variables and note on adjustments 

Origin

Variable

Units

Time period for
monthly means

Time period for
monthly anomalies

Base line period for
monthly climatology

Adjustments

ERA5

0-7cm volumetric soil moisture

m3m-3

1979 - present

1979 - present

1981-2010
1991-2020

Yes, see here

ERA5

Total precipitation

m day-1

1979 - present

1979 - present

1981-2010
1991-2020

No

ERA5

Sea-ice cover

(0 - 1)

1979 - present

1979 - present

1981-2010
1991-2020

No

ERA5

Surface air relative humidity

%

1979 - present

1979 - present

1981-2010
1991-2020

No

ERA5

Surface air temperature

K

1979 - present

1979 - present

1981-2010
1991-2020

Yes, see here

ERA-Interim

0-7cm volumetric soil moisture

m3m-3

1979 - present

1979 - present

1981-2010

Yes, see here

ERA-Interim

Total precipitation

m day-1

1979 - present

1979 - present

1981-2010

No

ERA-Interim

Sea-ice cover

(0 - 1)

1979 - present

1979 - present

1981-2010

No

ERA-Interim

Surface air relative humidity

%

1979 - present

1979 - present

1981-2010

Yes, see here

ERA-Interim

Surface air temperature

K

1979 - present

1979 - present

1981-2010

Yes, see here

ERA5

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era5surftempadj
era5surftempadj
Surface air temperature

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Table 2: Information about GRIB codes, version numbers and differences between version numbers.

Origin

Variable

GRIB
code

Grid

Version number

Difference between v01
and v02

Difference between
v02 and v03

ERA5

0-7cm volumetric soil moisture

39

.25/.25

v02

12 m running mean statistics reprocessed


ERA5

Total precipitation

228

.25/.25

v02

12 m running mean statistics reprocessed


ERA5

Sea-ice cover

31

.25/.25

v02

12 m running mean statistics reprocessed


ERA5

Surface air relative humidity

157

.25/.25

v02

12 m running mean statistics reprocessed


ERA5

Surface air temperature

167

.25/.25

v02

Reprocessing adjustment over Great Lakes only, updated interpolation package for regridding to regular grid.* 12 m running mean statistics reprocessed


ERA-Interim

0-7cm volumetric soil moisture

39

.25/.25

v02/v03

Applied masking over sea, ice sheets and deserts;
Grid changed to regular

12 m running mean statistics reprocessed

ERA-Interim

Total precipitation

228

.25/.25

v02/v03

Grid changed to regular

12 m running mean statistics reprocessed

ERA-Interim

Sea-ice cover

31

.25/.25

v02/v03

Grid changed to .25/.25

12 m running mean statistics reprocessed

ERA-Interim

Surface air
relative humidity

157

.25/.25

v02/v03

Grid changed to regular; GRIB code changed

12 m running mean statistics reprocessed

ERA-Interim

Surface air temperature

167

.25/.25

v02/03

Adjustments over ice-free seas applied; GRIB code changed

12 m running mean statistics reprocessed

Known issues

  • Update from v01 to v02 of ERA5 surface air temperature:

...

The outdated and new maps of hydrological variables for Europe for October highlight the main difference between the dataset containing the erroneous values and the new one based on the consolidated ERA5. The issue is very apparent in Central Asia in the soil moisture maps and, to some extent, for the other variables too. 


Old erroneousNew corrected

Image Modified

Image Modified

Figure 1: Anomalies in precipitation, the relative humidity of surface air, the volumetric moisture content of the top 7 cm of soil and surface air temperature for October 2021 with respect to October averages for the period 1991-2020. The darker grey shading denotes where soil moisture is not shown due to ice cover or climatologically low precipitation. Data source: Left ERA5T (erroneous), Right: ERA5 consolidated (new & corrected) Credit: Copernicus Climate Change Service/ECMWF.

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table3
table3
Table 3: Original erroneous and the new corrected versions of data and graphics.


  • Incomplete retrieval of ERA5 during DHS move affecting RH used in the Climate bulletin 

The “Essential climate variables for assessment of climate variability from 1979 to present" dataset constitutes the basis for the C3S monthly Climate Bulletin 

In the frame of a major hardware change at ECMWF, and for a limited period, the services usually provided by the Data Handling System, from which this dataset is retrieved, were distributed across different systems. For this, a bespoke retrieval script was developed, within which an error led to the incomplete retrieval of surface air relative humidity data for the month of September 2022. Instead of covering the period 1-30 September, the retrieved files only contained the data for the period 07-30 September. This one-off problem, had an impact on all data and information derived from those, namely the data for September and October 2022. Upon publication of data for November 2022, the problem was identified and the data for the month of September 2022 correctly retrieved. As of mid-December 2022, the published "Essential climate variables for assessment of climate variability from 1979 to present" data have thus been replaced on the CDS for each of the affected months with a new version.   

 In turn, related maps, time-series and data of the monthly climate bulletin have been accordingly updated and replaced for the affected months in the respective bulletin. The table of the bottom of the page outlines which months have been updated to date.  

 

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table4
table4
Table 4: Original erroneous and the new corrected versions of data and graphics. 

 

 

September 

October 

Old erroneous 

Zip-file of data and graphics (1981-2010, 1991-2020) 

Zip-file of data and graphics (1981-2010, 1991-2020) 

New corrected graphics and time-series data 

September monthly summary 

October monthly summary 

Corrected spatial data available in the CDS entry? 

yes 

yes 

Date of correction 

22/12/2022 

22/12/2022 

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references
references
References

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