In 2024, the World Meteorological Organization (WMO) approved the inclusion of global climate reanalysis in its WMO Integrated Processing and Prediction System (WIPPS), which means it is now formally an operational activity. This will ensure that global reanalyses are continually produced and made available to users, alongside clear documentation and visualisation tools. ECMWF is one of three current designated centres, contributing the ERA5 reanalysis, and it is also the lead centre of this activity.
WMO WIPPS
The WMO has an intergovernmental mandate for coordinating the generation and exchange of weather, climate, and water information across its members. It has successfully coordinated the production and provision of weather forecasts and climate predictions from international operational centres, from short-range to medium-range, sub‑seasonal, seasonal and decadal timescales.
In June 2024, the WMO Executive Council (EC-78) approved the inclusion of two WIPPS-Designated Centres (DCs) related to climate reanalysis:
- WIPPS-DCs for Global Climate Reanalysis
- WIPPS-DCs for Coordination of assessment of multiple climate reanalysis
After the approval by EC‑78, climate reanalysis is now formally an operational activity within WIPPS and is on a par with forecasting activities.
Designated centres
At present, there are three WIPPS‑DCs for Global Climate Reanalysis: ECMWF, the China Meteorological Administration (CMA), and the US National Aeronautics and Space Administration (NASA).
The Japanese Meteorological Agency (JMA) is not formally part of the project yet but hopes to be made an official WIPPS‑DC during the summer of 2025.
CMA, ECMWF, and NASA will provide CRA-40 (1979–present), ERA5 (1940–present), and MERRA2 (1980–present), respectively. Finally, JMA will contribute JRA-3Q (September 1947–present) once it is officially a designated centre. The approximate horizontal resolutions of CRA‑40, ERA5, MERRA2, and JRA-3Q are 34, 31, 50, and 40 km, respectively.
ECMWF is the WIPPS‑DC for Coordination of assessment of multiple climate reanalysis. In this capacity, ECMWF will facilitate intercomparison of global reanalysis products from different centres, with the provision of comparable data on identical grids, graphical products, and visualisation tools.
Development phases
During the initial phase of this activity, we are gathering historical monthly mean data from 1991–2020 (the WMO climatological period). We are starting with three principal variables of total precipitation, 2 m temperature, and mean sea level pressure.
In the future, additional mandatory products at the surface will be added, including pressure, land–sea mask, topography, sea‑surface temperature, sea-ice cover, snow water equivalent, incoming short-wave radiation, outgoing long-wave radiation, 2 m specific humidity, 10 m winds, alongside geopotential height, temperature, winds, and specific humidity data on pressure levels.
Along with the inclusion of more variables, in future phases we will gather data at higher temporal resolution, and within no more than 60 days behind real time.
Global climate reanalyses are widely used in a range of diverse applications, and this significant step forward in making them operational will benefit many sectors. We are working closely with CMA, JMA, and NASA on the provision of initial data for phase 1 and will ultimately host a platform with several mandatory products that are regularly updated, with the ability to visualise data and conduct intercomparisons.
ECMWF’s web page on being the lead centre for global climate reanalyses is here: https://confluence.ecmwf.int/display/GCR/WMO+Lead+Centre+for+Global+Climate+Reanalyses+LC-GCR.