ECMWF offers three file-naming convention templates for real-time product delivery via the ECMWF Production Data Store (ECPDS). These templates can be selected using the Product Requirements Editor (PRED) if you have access, otherwise requests of template change can be made through the ECMWF Support Portal.

LEGACY Template
- Currently used for all real-time IFS products delivered through ECPDS.
- AIFS products are not configurable with this template.
- This template will be phased out in 2026.
ECMWF Template
- Currently used for all real-time AIFS products delivered through ECPDS.
- IFS products are configurable to use this template.
WMO Template
- Configuration for both IFS and AIFS products delivered through ECPDS are supported.

1. LEGACY

Feed	Stream	BasedDate (MMDDHHmm)	ValidDate (MMDDHHmm)	Experiment
A1	D	07 25 00 00	08 08 18 00	1
A1D07250000080818001

Feed: The feed name, as defined in the PREd
Stream: The stream indicator (see table below)
Based Date: The month, day, hour and minute on which the products are based (in MMDDHHmm format)
Valid Date: The month, day, hour and minute at which the products are valid (in MMDDHHmm format)
- MMDDHHmm is set to "MM______" for seasonal forecast products, where MM indicates the valid month
- mm is set to "01" for high resolution forecast (type=fc, step=0)
Experiment: The version number (as EXPVER keyword in MARS, operational files use 1).

1.1. Stream indicator

S	Stream, Type	Description	Forecast Range	Runs Frequency
A	stream=oper, type=wp	HRES Weather Parameter products	15-day	00z/12z daily
B	stream=enfo, type=wp	ENS Weather Parameter products	15-day	00z/12z daily
C	stream=oper/scda, type=tf	HRES Tropical Cyclone trajectory products	10-day	00z/06z/12z/18z daily
D	stream=oper	HRES Atmospheric model products	15-day	00z/12z daily
E	stream=enfo	ENS Atmospheric model products	15-day	00z/12z daily
F	stream=eefo	ENS Subseasonal atmospheric model products	46-day	00z daily
G	stream=waef	ENS Wave model products	15-day	00z/06z/12z/18z daily
H	stream=eefh/eehs	ENS Subseasonal atmospheric model re-forecast products	46-day	00z every other day (1/3/5...)
I	stream=enfh/efhs	ENS Atmospheric model re-forecast products	15-day	00z every four days (1/5/9...)
J	stream=enwh/wehs	ENS Wave model re-forecast products	15-day	00z every four days (1/5/9...)
L	stream=mmsm/mmsf/mmsa	ENS Seasonal model forecasting system products (SEAS)	7-months	00z monthly
M	stream=oper, type=fc	HRES Atmospheric model products for Thermofeel* parameters	15-day	00z/06z/12z/18z daily
N	stream=wasf	ENS Seasonal model products (SEAS-WAM)	7-months	00z monthly
O	stream=enfo, type=pf/cf	ENS Atmospheric model products for Thermofeel* parameters	15-day	00z/06z/12z/18z daily
P	stream=wave	HRES Wave model products (HRES-WAM )	15-day	00z/12z daily
Q	stream=scwv	HRES Wave model products (HRES-WAM )	15-day	06z/18z daily
S	stream=scda	HRES Atmospheric model products	15-day	06z/18z daily
T	stream=enfo, type=tf	ENS Tropical Cyclone trajectory products	15-day	00z/06z/12z/18z daily
U	stream=waef, type=em/efi/sot/ep	ENS Wave model post-processed products	15-day	00z/06z/12z/18z daily
V	stream=weef	ENS Subseasonal wave model products (ENS-WAM)	46-day	00z daily
W	stream=waef	ENS Wave model probabilistic products (ENS-WAM)	15-day	00z/06z/12z/18z daily
X	stream=enfo	ENS Atmospheric model products	15-day	00z/06z/12z/18z daily
Y	stream=enfo, type=em/efi/sot/ep	ENS Post-processed atmospheric model products	15-day	00z/06z/12z/18z daily
Z	stream=weeh/wees	ENS Subseasonal re-forecast wave model products	46-day	00z daily

(*) 2 metre relative humidity (2r), Apparent temperature (aptmp), Globe temperature (gt), Heat index (heatx), Humidex (hmdx), Mean radiant temperature (mrt), Normal effective temperature (nefft), Universal thermal climate index (utci), Wet bulb globe temperature (wbgt), Wind chill factor (wcf)

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2. ECMWF

Destination	Feed	ModelName	Class	Stream	Type	BasedDate (YearMonthDayTHourMinuteSecondsZ)	ValidDate (YearMonthDayTHourMinuteSecondsZ)	Step	Experiment (Optional)
abc	a1	aifs-ens	ai	enfo	pf	20250725T000000Z	20250808T180000Z	354
abc_a1_aifs-ens_ai_enfo_pf_20250725T000000Z_20250808T180000Z_354h

Destination: The destination name used in ECPDS. The file-naming convention will always use the name of the primary destination where the data are installed, even if you receive the files via an alias destination.
Feed: The feed name, as defined in the PREd
ModelName: The model identifier
Class: The class of forecast data
Stream: The stream name
Type: The type of forecast
BasedDate: The base date and time of the product, in the format YYYYMMDDTHHMMSSZ (ISO 8601 format) (This marks when the forecast was initiated)
ValidDate: The date and time for which the product is valid, in the format YYYYMMDDTHHMMSSZ (ISO 8601 format) (This marks the time the forecast is intended to represent)
Step: The forecast step in hours or days
Experiment: The experiment version number (as EXPVER keyword in MARS, operational files use 1) (Not shown when operational)

3. WMO

PFlag	ProductIdentifier (locationIndicator,modelName,destination+ feed+class+stream+type +expver)	OFlag	Originator	ProductionDate (YearMonthDayTHourMinuteSecondsZ)	FreeFormat (ValidDate_Step_FileFormat)	Extension
W	xx-ecmwf-reading,aifs+single,egs+e5+ai+oper+fc+0001	C	ECMF	20250725T000000Z	20250808T180000Z_354h_grib	bin
W_xx-ecmwf-reading,aifs+single,abc+a1+ai+enfo+pf+0001_C_ECMF_20250725T000000Z_20250808T180000Z_354h_grib.bin

PFlag: Indicating how to decode the product identifier field
ProductIdentifier: Comma-separated values indicating the location, model name, and product metadatalocationIndicator
- Location: The WMO location indicator of the production centre
- ModelName: The model identifier
- Destination: The destination name used in ECPDS. The file-naming convention will always use the name of the primary destination where the data are installed, even if you receive the files via an alias destination.
- Feed: The feed name, as defined in the PREd
- Class: The class of forecast data
- Stream: The stream name
- Type: The type of forecast
- Expver: The experiment version number (as EXPVER keyword in MARS, operational files use 1) (Not shown when operational)
OFlag: Indicating how to decode the originator field
Originator: WMO originator code
ProductionDate: Based date and time of the product, in the format YYYYMMDDTHHMMSSZ (ISO 8601 format) (This marks when the forecast was initiated)
FreeFormat: A free-format field containing valid date, step and file format
- ValidDate: The date and time for which the product is valid, in the format YYYYMMDDTHHMMSSZ (ISO 8601 format) (This marks the time the forecast is intended to represent)
- Step: The forecast step in hours or days
- FileFormat: The format of the data file
Extension: The file extension

File Format

About half of ECMWF products are encoded in WMO FM-92 GRIB edition 1, and the other half in GRIB edition 2, unless otherwise specified in our Catalogue of Real-time products.

However, some product subsets use different encoding formats:

HRES Atmospheric model (Product subset I-i-c) and ENS Atmospheric model (III-i-c):
- Model level parameters are encoded in WMO FM-92 GRIB edition 2.
  For more details, see the Migration to GRIB edition 2 Information page.
AIFS model products are encoded in WMO FM-92 GRIB edition 2.
Time Series of Weather Parameters (Product subsets I-ii, III-iv) and Tropical Cyclones (I-iii, III-viii):
- These are encoded in WMO FM-94 BUFR format.

Possible ModelName, Class and Streams for ECMWF and WMO templates

Full Name	ModelName	Class	Stream	Type	Model
IFS High Resolution Data Assimilation	ifs-da	od	oper/wave	an
IFS Medium-range Ensemble Forecast	ifs-ens	od	enfo/waef
IFS Medium-range Control Forecast	ifs-ens-cf	od	oper/wave/scda/scwv
IFS Medium-range Reforecast	ifs-ens-refc	od	enfh/enwh/efhs/wehs
IFS Sub-seasonal Forecast	ifs-subs	od	eefo/weef
IFS Sub-seasonal Reforecast	ifs-subs-refc	od	eefh/weeh/eehs/wees
IFS Seasonal Forecast	ifs-seas	od	mmsf/msmm/mmsa/swmm/wasf
AIFS Single Forecast	aifs-single	ai	oper	fc	aifs-single
AIFS Ensemble Forecast	aifs-ens	ai	enfo	cf/pf	aifs-ens

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File naming convention and format for real-time data

1. LEGACY

1.1. Stream indicator

(*) 2 metre relative humidity (2r), Apparent temperature (aptmp), Globe temperature (gt), Heat index (heatx), Humidex (hmdx), Mean radiant temperature (mrt), Normal effective temperature (nefft), Universal thermal climate index (utci), Wet bulb globe temperature (wbgt), Wind chill factor (wcf)

2. ECMWF

3. WMO