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A user of our ERA-Interim dataset asked: How does ERA-Interim deal with lakes, specifically Lake Victoria?

  • Is it open water (not eg. some kind of marsh)?
  • If yes, where does its surface temperature come from?


The answer from our scientists:

In ERA-Interim the surface water temperature of Lake Victoria and most open-water bodies (with the exception of US Great-lakes) are specified by a monthly climatology and therefore will not display any variability year-after-year which might be particularly inaccurate in anomalously warm years.

The climatology was generated by a 2m temperature gridded field (at low resolution of about 1degree) lagged by one month to represent some of the thermal inertia effect of lakes. Over lake Victoria that is particularly poor due to orography discrepancy of the lake surface elevation.

Lake Victoria temperatures are expected to be more accurate in the ERA5 reanalysis (in which lake thermodynamics is represented by a dedicated scheme).

ERA-Interim production to stop on 31st August 2019

As ERA5 is now available (What are the changes from ERA-Interim to ERA5?), we are preparing to stop the production of ERA-Interim on 31st August 2019. This means that the complete span of ERA-Interim data will be from 1st January 1979 to 31st August 2019.

Keeping in mind that ERA-Interim is published with an offset of about three months from the dataset's reference date, ERA-Interim August 2019 data will be made available towards the end of 2019.

For the time being and until further notice, ERA-Interim shall continue to be accessible through the ECMWF Web API. ERA5 is available from the Climate Data Store (CDS).