| Note |
ERA-Interim combines information from meteorological observations with background information from a forecast model, using the data assimilation approach developed for numerical weather prediction. The reanalysis process blends observations (over a 12 hour period) with a short forecast to produce analyses, from which the short forecasts are run.
ERA-Interim runs a few days behind real time. The ERA-Interim monthly means are generated by averaging 6 hourly analyses and 6 hourly forecast fields from the twice daily forecasts. Once ERA5 is available for the period 1979 to the present, ERA5 will be used to generate monthly products. ERA5 monthly means are generated from hourly fields.
Potentially, all the observations, over the whole globe from the surface of the Earth to the top of the atmosphere for the whole 12 hours, as well as the forecast (which depends on past observations) can have an impact on any field at a given location in time and space. However, some in-situ observations will have a larger impact on a particular product than others. |