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Info
for hindcastYear in hindcastYears
    for hindcastMonth in hindcastMonths        
        for hindcastDay in hindcastDays             
            hindcastDate = hindcastYear-hindcastMonth-hindcastDay               
            S2S-request(hindcastDate)

Web-API examples:

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An ECMWF reforecast request for all the available hindcastDates

Info
  • The objective of this example is to demonstrate how to iterate efficiently over all the available hindcastYears, hindcastMonths and hindcastDays for a ECMWFreforecast request
  • 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 ECMWFreforecast. Don't forget to check ECMWFavailabilityECMWF availability (warning)

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

origin = "ecmf"
modelVersionDate = "2014-01-01"

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
    """
    hindcastYearStart = 1981
    hindcastYearEnd = 2013
    hindcastMonthStart = 1
    hindcastMonthEnd = 12
    # ECMWFavailabilityECMW Favailability is every 5 days: 1, 6, 11, 16, 21, 26
    hindcastDays = [1, 6, 11, 16, 21, 26]

    #Step 1: Iterate over all the available hindcastYear(s)
    for hindcastYear in list(range(hindcastYearStart, hindcastYearEnd + 1)):
        #Step 2: Iterate over all the available hindcastMonths(s)       
        for hindcastMonth in list(range(hindcastMonthStart, hindcastMonthEnd + 1)):
            hindcastDates = []
            #Step 3: Create the list of the available hindcastDates
            for hindcastDay in hindcastDays:
                hindcastDate = '%04d%02d%02d' % (
                    hindcastYear, hindcastMonth, hindcastDay)
                hindcastDates.append(hindcastDate)
           
            #Please note: the steps 4 and 5 below could run in parallel
           
            #Step 4: Get all the available perturbed forecast, pressure level data
            pfplTarget = "%s_%s_%04d%02d.grb" % (
                origin, "pfpl", hindcastYear, hindcastMonth)
            ECMWF_reforecast_pf_pl_request("/".join(hindcastDates), pfplTarget)
           
            #Step 5: Get all the available perturbed forecast, surface data
            pfsfcTarget = "%s_%s_%04d%02d.grb" % (
                origin, "pfsfc", hindcastYear, hindcastMonth)
            ECMWF_reforecast_pf_sfc_request("/".join(hindcastDates), pfsfcTarget)

def ECMWF_reforecast_pf_pl_request(hindcastDate, target):
    """
       A ECMWFreforecast, 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": hindcastDate,
        "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/1488/by/24",
        "stream": "enfh",
        "target": target,
        "time": "00",
        "number": "1/to/32",
        "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": "31/34/121/122/136/146/147/151/167/168/169/175/176/177/179/180/181/235/228086/228095/228096/228141/228143/228144/228164/228228",
        "step": "24/to/1488/by/24",
        "stream": "enfh",
        "target": target,
        "time": "00",
        "number": "1/to/32",
        "type": "pf",
    })

if __name__ == '__main__':
    retrieve_ECMWF_reforecast()

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