Atmospheric general circulation component

Table 1a: Key characteristics of the atmospheric component of the IFS based on Cycle 49r1

	Forecast / Analysis	Number of members	Horizontal resolution	Vertical levels	Pressure at model top (hPa)	Perturbation models
CTRL (former HRES) Atmospheric Model control forecast Data Graphical products	Forecast 0–15 days	1	Native ⁽¹⁾: O1280 ~9km Interpolated ⁽²⁾: 0.1° ~9km	137	0.01 hPa	No
ENS Ensemble - Atmospheric Model Data Graphical products	Forecast 0–15 days	51	Native ⁽¹⁾: O1280 ~9km Interpolated ⁽²⁾:0.1°	137	0.01 hPa	Yes⁽⁴⁾
ENS Sub-seasonal Atmospheric Model Sub-seasonal forecast Data Graphical products	Forecast 0–46 days once a day at 00 UTC	101	Native ⁽¹⁾: O320 ~36km Interpolated ⁽²⁾: 0.4°	137	0.01 hPa	Yes ⁽⁴⁾
4DVAR 4-Dimensional data assimilation Data (See Analysis in HRES) Graphical products	Analysis	1	N128/N160/N200/N256 inner loop minimisations 4 outer loops at O1280 resolution	137	0.01 hPa	No
EDA Ensemble of data assimilations Data	Analysis	51	N200/N200/N256 inner loop minimisations 3 outer loops at O1280 resolution	137	0.01 hPa	Yes ⁽⁵⁾
SEAS5 2017 version Cycle 43r1 Seasonal forecast Data Graphical products	Forecast long-range forecast run monthly from 0 to 7 months annual range forecast run quarterly from 0 to 13 months	51 15	Native ⁽¹⁾:O320 ~36km Interpolated ⁽²⁾: 0.4°	91	0.01 hPa	Yes ⁽⁴⁾

Ensemble and seasonal re-forecasts

Table 1b: Key characteristics of the ENS and SEAS re-forecasts of the ECMWF IFS

Forecast/Analysis

Number of members

Horizontal resolution

Vertical levels

Pressure at model top (hPa)

Perturbation models

Number of years

ENS medium range

0–15 days
runs of 1/5/9/13/17/21/25/29 of the month
(excluding 29 February)

11

Native ⁽¹⁾: O640
Interpolated⁽²⁾: 0.25° ~28km

137

0.01 hPa

Yes ⁽⁴⁾

Most recent 20

ENS sub-seasonal range

0–46 days
runs of 1/3/5/7/9/11/13/15/17/19/21/23/25/27/29/31
of the month (excluding 29 February)

11

Native ⁽¹⁾: O320 ~36km
Interpolated ⁽²⁾: 0.4°

137

0.01 hPa

Yes ⁽⁴⁾

Most recent 20

SEAS5 Cycle 43r1

Seasonal forecast

Forecast

run monthly
0–7 months (monthly)

run quarterly 0-13 months (annual range)

25

15

Native ⁽¹⁾:O320 ~36km
Interpolated ⁽²⁾: 0.4°

91

0.01 hPa

Yes ⁽⁴⁾

36 (1981-2016)

Ocean general and sea ice

Table 1c: Key characteristics of the ocean component general circulation models of the ECMWF IFS

Forecast/Analysis

Number of members

Horizontal resolution

ORCA grid

Vertical levels

NEMO (LIM-2)

Forecast

daily (HRES and ENS)
run monthly
0–7 months (monthly)
run quarterly 0-13 months (annual range)

51

0.25°

75

Oceans

OCEANS-BRT (Behind Real-Time)
OCEANS-RT (Real-Time)

Analysis

Reanalysis

5

0.25°

75

Ocean-wave component

Table 1d: Key characteristics of the ocean-wave component of the ECMWF IFS

	Forecast/Analysis	Domain	Number of members	Horizontal resolution
CTRL-WAM Ocean Wave coupled to the atmospheric model Data Graphical products	Analysis and forecast 0–15 days	Global	1	Native ⁽¹⁾: O1280 ~9km Interpolated ⁽²⁾: 0.1° ~9km
ENS-WAM medium range Ensemble wave medium range forecast Data Graphical products	Forecast 0-15 days	Global	51	Native ⁽¹⁾: O1280 ~9km Interpolated ⁽²⁾: 0.1°
ENS-WAM sub-seasonal range Ensemble wave sub-seasonal forecast Data Graphical products	Forecast 0-46 days	Global	101	Native ⁽¹⁾: O320 ~36km Interpolated ⁽²⁾: 0.4°
SEAS-WAM Seasonal wave forecast	Forecast run monthly 0–7 months (monthly) run quarterly 0-13 months (annual range)	Global	51	Native ⁽¹⁾: O320 ~36km Interpolated ⁽²⁾: 0.4°

Atmospheric and Ocean-wave reanalysis ERA5

ERA5, based on IFS Cycle 41r2, is used to initialise ensemble reforecasts.

	Forecast/Analysis	Number of members	Horizontal resolution	Vertical levels	Pressure at model top (hPa)	Perturbation models
ERA5 Atmospheric high resolution reanalysis Data Documentation	Analysis Forecast	1	~ 31km, 0.28125 degrees (at the equator) Depending on the parameter, the data are archived either as spectral coefficients with a triangular truncation of T639 or on a reduced Gaussian grid with a resolution of N320.	137	0.01	No
ERA5 EDA Atmospheric reduced resolution ensemble Data Documentation	Analysis Forecast	10	~ 63km, 0.5625 degrees (at the equator) Depending on the parameter, the data are archived either as spectral coefficients with a triangular truncation of T319 or as N160 reduced Gaussian grid.	137	0.01	Yes ⁽⁵⁾
ERA5 wave Ocean wave model (WAM) reanalysis Data Documentation	Analysis Forecast	1	0.36 degrees	1	-	No
ERA5 wave EDA Ocean wave reduced resolution ensemble Data Documentation	Analysis Forecast	10	1.0 degrees	1	-	Yes ⁽⁵⁾

4D-Var data available for all the 4 entries.

⁽¹⁾ Native: as produced by the model on reduced Gaussian grids or spherical harmonics.

⁽²⁾ Interpolated to lat/lon

⁽³⁾Native: as produced by the model on reduced lat/lon grids.

⁽⁴⁾ in analysis and model physics

⁽⁵⁾ in observations and model physics