ERA5

ERA5 is a global atmospheric reanalysis dataset produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) as part of the Copernicus Climate Change Service. It provides hourly estimates of a wide range of atmospheric, surface, and near-surface variables on a regular grid for the period from 1950 to the present. ERA5 is designed to yield a consistent, long-term climate record by combining a modern numerical weather prediction model with a comprehensive suite of observations through a data assimilation system.

The dataset has a horizontal resolution of about 0.25 degrees (approximately 25 km) and offers hourly outputs with 137 vertical levels extending up to about 80 km. It covers many atmospheric variables such as temperature, humidity, wind, geopotential, pressure, and precipitation, as well as surface and boundary-layer fluxes and radiation. The information is produced by ECMWF’s Integrated Forecasting System (IFS) using four-dimensional variational data assimilation to optimally blend model information with observations from ground-based stations, ships, aircraft, and satellites.

ERA5 data are freely available via the Copernicus Climate Data Store (CDS) and are widely used in climate research, weather forecasting, hydrology, agriculture, and energy applications. The dataset represents a significant improvement over its predecessor, ERA-Interim, in temporal and spatial resolution, coverage back to 1950, and the breadth of variables. Related products include ERA5-Land, which provides higher-resolution land-surface data. While ERA5 is a reanalysis and not a forecast, users should still consider uncertainties, especially in data-sparse regions and for extreme events.