Hourly weather and climate snapshots starting in 1940 are now available

Hourly weather and climate snapshots starting in 1940 are now available

The Copernicus Climate Change Service (C3S*) now provides an additional 19 years of reanalysis data from ERA5, the fifth generation reanalysis of global climate and weather from the European Center for Medium-Range Weather Forecasts. This extends the ERA5 data record back over 83 years, from 1940 to the present day.

C3S actively monitors the evolution of our weather and climate. However, to understand the current climate and measure change over time, it is necessary to first understand the past. This is where ERA5 comes into play. The ERA5 reanalysis provides hourly snapshots of the global atmosphere, land surface and ocean waves, providing data on many key climate variables. ERA5 is updated daily with a latency of about 5 days.

As such, ERA5 is the backbone of many C3S products and services, including its monthly climate bulletins. “With more than 100,000 registered users, ERA5 is a very popular dataset in the C3S Climate Data Store (CDS) with a wide range of user profiles,” said Hans Hersbach, C3S Reanalysis Team Leader.

Three hourly snapshots of the 1941 Iberian Storm, showing mean ERA5 sea level pressure (profiles, in hPa) and the hourly 10-meter maximum (colors, in m/s). The locations of the absorbed pressure and offshore wind observations from which these ERA5 reanalysis fields were generated are shown as dark red circles.

ERA5 combines historical weather observations with state-of-the-art computer models of the Earth system to build a complete global picture of climate over the past decades. The dataset covers temperature, surface pressure, wind, ocean wave height and much more, and creates “gapless maps” by filling in places where observations are lacking – for example at times when clouds prevent satellites from observing the Earth’s surface, or Places like the Arctic that are difficult to reach with ground tools.

For the early ERA5 period, the number of input observations available is limited. “This is where the presented ERA5 ensemble adds important value to evaluate the accuracy of time- and location-dependent early posterior extension filling,” Hersbach said.

“This new update to ERA5 extends the data record back in time, enriching its collection of extreme weather events and providing important information for the reinsurance industry,” said Carlo Bontempo, Director, C3S. “One example is the ERA5 representation of a record storm over the Iberian Peninsula 82 years ago – in February 1941.” (see above)

The initial ERA5 rear extension was already available from 1950 to 1958 – access to this initial product will be discontinued in due course, as it is replaced by the new ERA5 extension.

*C3S is implemented by the European Center for Medium-Range Weather Forecasts on behalf of the European Commission.

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