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The objective of this example is to demonstrate how to iterate efficiently over all the available hindcastYears, hindcastMonths and hindcastDays for an ECMWF model version date.
You firstly need to know the model version date and the correct Hindcast Days you wish to request. For more information you may wish to visit
It can be used as a starting point, however you need to keep in mind that you have to adapt it to your needseg to set the keyword values according to your requirements ("param", "levtype", "step" etc).
In this way you can extend this request to download the whole S2S ECMW Freforecast. Don't forget to check ECMWF availability

Please note:

the most efficient way is to request all hindcastDates of a hindcastMonth, in one request, like the example below.
you can use the variable target to write the requested data as you wish. In the example below the data is written per leveltype (sfc, pl) per hindcastMonth.

Code Block

language	py

#!/usr/bin/env python
from ecmwfapi import ECMWFDataServer
server = ECMWFDataServer()

origin = "ecmf"
modelVersionDate = "2015-12-03"

def retrieve_ECMWF_reforecast():
    """
       A function to demonstrate how to iterate efficiently over all hindcastYears, hindcastMonths etc
       for a particular ECMWF_reforecast_request.
       Change the variables below to adapt the iteration to your needs
    """
    # ECMWF availability is every 5 days: 1, 6, 11, 16, 21, 26
    hindcastDays = hindcastDates = ["1995-12-03/", "1996-12-03/", "1997-12-03/", "1998-12-03/", "1999-12-03/", "2000-12-03/",
    "2001-12-03/", "2002-12-03/", "2003-12-03/", "2004-12-03/", "2005-12-03/", "2006-12-03/", "2007-12-03/", 
    "2008-12-03/", "2009-12-03/", "2010-12-03/", "2011-12-03/", "2012-12-03/", "2013-12-03/", "2014-12-03"]

    #Step 1: Iterate over all the available hindcastYear(s)def retrieve_ECMWF_reforecast():
    for"""
 hindcastYear in list(range(hindcastYearStart, hindcastYearEnd + 1)):
 A function to demonstrate how to iterate #Step 2: Iterate efficiently over all the available hindcastMonths(s)       
 hindcastDays 
       for hindcastMontha in list(range(hindcastMonthStart, hindcastMonthEnd + 1)):particular ECMWF reforecast model version.
       Change the variables below to hindcastDates = []
            #Step 3: Create the list of the available hindcastDatesadapt the iteration to your needs
            for hindcastDay in hindcastDays:
       """
         hindcastDate = '%04d%02d%02d' % (
                    hindcastYear, hindcastMonth, hindcastDay)
                hindcastDates.append(hindcastDate)
           
            #Please #Please note: the steps 4 and 5 below could run in parallel
           
            #Step #Step 4: Get all the available perturbed forecast, pressure level data
            pfplTarget = "%s_%s_%04d%02d%_%s.grb" % (
                origin, "pfpl", hindcastYear, hindcastMonthmodelVersionDate)
            ECMWF_reforecast_pf_pl_request("/".join(hindcastDates), pfplTarget)
           
            #Step 5: Get all the available perturbed forecast, surface data
            pfsfcTarget = "%s_%s_%04d%02d%_%s.grb" % (
                origin, "pfsfc", hindcastYear, hindcastMonthmodelVersionDate)
            ECMWF_reforecast_pf_sfc_request("/".join(hindcastDates), pfsfcTarget)

def ECMWF_reforecast_pf_pl_request(hindcastDate, target):
    """
       A ECMWF ECMWFreforecastreforecast, perturbed forecast, pressure level, request.
       The cost of this request is 571,392 fields and 11.1352 Gbytes 
       Change the keywords below to adapt it to your needs.
    """
    server.retrieve({
        "class": "s2",
        "dataset": "s2s",
        "date": modelVersionDate,
        "expver": "prod",
        "hdate": hindcastDatehindcastDates,
        "levtype": "pl",
        "levelist": "10/50/100/200/300/500/700/850/925/1000",
        "origin": origin,
        "param": "130/131/132/133/135/156",
        "step": "24/to/1488768/by/24",
        "stream": "enfh",
        "target": target,
        "time": "00",
        "number": "1/to2/3/324",
        "type": "pf",
    })

def ECMWF_reforecast_pf_sfc_request(hindcastDate, target):
    """
       A ECMWFreforecast, perturbed forecast, sfc request.
       The cost of this request is 383,040 fields and 7.1 GB
       Change the keywords below to adapt it to your needs.
    """
    server.retrieve({
        "class": "s2",
        "dataset": "s2s",
        "date": modelVersionDate,
        "expver": "prod",
        "hdate": hindcastDate,
        "levtype": "sfc",
        "origin": origin,
        "param": "311/33/34/59/121/122/134/136/146/147/151/165/166/167/168/169/175/176/177/179/180/181/235/228086/228095/228096/228141/228143/228144/228164/228228",
        "step": "24/to/1488744/by/24",
        "stream": "enfh",
        "target": target,
        "time": "00",
        "number": "1/to2/3/324",
        "type": "pf",
    })

if __name__ == '__main__':
    retrieve_ECMWF_reforecast()

Useful links

Info
ECMWFreECMWF re-forecast requests ECMWF Web API Home ECMWFreECMWF re-forecast availability A brief description of reforecasts

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