Following practice at several international operational centres, and recommendations from WMO, we have introduced a relative index to describe the ENSO state in forecasts, as well as in monitoring. Details of the definition of this new index, and its variations through the historical record, are available in the following places:
- a brief C3S article on ENSO impacts
- C3S seasonal documentation pages with additional details on the products descriptions.
- ECMWF blog post “Measuring the strength of El Niño – introducing Relative Niño indices”
Graphical products routinely produced for all the C3S seasonal forecast contributions and the multi-system combination can be found in the C3S seasonal charts page.
