What are the changes from ERA-Interim to ERA5?

Changes for all ERA5 datasets

	ERA-Interim	ERA5
Period covered	1979 - present	1979 - present
Production Period	August 2006 – end 2018	Jan 2016 – end 2017, then continued in near real-time
Assimilation system	IFS Cycle 31r2 4D-Var	IFS Cycle 41r2 4D-Var
Model input	As in operations (inconsistent SST)	Appropriate for climate (e.g. CMIP5 greenhouse gases, volcanic eruptions, SST and sea-ice cover)
Input observations	As in ERA-40 and from Global Telecommunication System	In addition, various newly reprocessed datasets and recent instruments that could not be ingested in ERA-Interim
Variational bias scheme	Satellite radiances	Also ozone, aircraft and surface pressure data
Satellite data	RTTOV-7, clear-sky, 1D-VAR rainy radiances	RTTOV-11, all-sky for various components
New parameters		tbd
Parameters removed		tbd
Handling of accumulated parameters	Accumulated from the beginning of the forecast	Accumulated from previous post-processing Does this mean from beginning of the Step?
Product main page	http://www.ecmwf.int/en/research/climate-reanalysis/era-interim	http://climate.copernicus.eu/climate-reanalysis
Technical documentation	Berrisford et al 2011: The ERA-Interim archive Version 2.0	ERA5 documentation (not yet...)
Additional innovations		Long-term evolution of CO2 in RTTOV, cell-pressure correction SSU, improved bias correction for radiosondes, EDA perturbations for sea-ice cover

	ERA-Interim	ERA5
Spatial resolution	79 km globally, 60 levels to 0.1 hPa	31 km globally, 137 levels to 0.01 hPa
Output frequency (temporal resolution)	6-hourly analysis, 3-hourly forecast fields	Hourly analysis and forecast fields, 3-hourly for the Ensemble of Data Assimilations (EDA)
Uncertainty estimates	None	From a 10-member Ensemble of Data Assimilations (EDA) at 63 km resolution
Additional innovations		Long-term evolution of CO2 in RTTOV, cell-pressure correction SSU, improved bias correction for radiosondes, EDA perturbations for sea-ice cover
		New parameters:
		Parameters removed: