An ECMWF reforecast request for all the available hindcastDates of an ECMWF model version date
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Table of Contents
What is the objective of this page?
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To help users to improve S2S ECMWF MARS requests performance via the WebAPI. A good understanding of the MARS efficiency issues is essential especially for users that are interested in downloading large amounts of data. |
How is the S2S reforecast data organised in MARS?
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In general it is organised, as a huge tree, with the indentation below, showing different levels down that tree:
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What would be the natural way to group requests?
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The idea is to request as much data as possible from the same tape file. The natural way to group requests would be: Note the following:
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Best practise to iterate over all hindcastDates of several hindcastYears for ECMWF
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The best approach is to iterate over the hindcastYears. For each hindcastYear iterate over all the available hindcastMonths and for each hindcastMonth iterate over all the available hindcastDays. At this point you may wish to check ECMWF availability and to view a ECMWF request |
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for hindcastYear in hindcastYears |
Web-API examples:
A ECMWF reforecast request for all the available hindcastDates
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Please note:
You can use the variable target to writeorganise the requested data in files as you wish . In the example below the data is written per leveltype (sfc, pl) per hindcastMonth. |
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#!/usr/bin/env python from ecmwfapi import ECMWFDataServer server = ECMWFDataServer() origin = "ecmf" # Step 1: Select a Model Version Date modelVersionDate = "20142015-0112-0103" 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 # ECMWFavailability 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 2: Set the hindcast Dates you wish to request # For the model version "2015-12-03" the available hindcast dates are listed below: 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"] def retrieve_ECMWF_reforecast(): """ A function to demonstrate how #Stepto 3:retrieve Createefficiently the list of the available hindcastDates all hindcastDates for hindcastDaya inparticular hindcastDays: ECMWF reforecast hindcastDate = '%04d%02d%02d' % (model version. Change the variables below to adapt the request to hindcastYear, hindcastMonth, hindcastDay)your needs hindcastDates.append(hindcastDate)""" # Please note #Please note: that the steps"sfc" 4and and"pl" 5requests below could run in parallel # #Step 4Step 1: 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 5Step 2: 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): """ An AECMWF ECMWFreforecastreforecast, perturbed forecast, pressure level, request. TheChange costthe ofkeywords thisbelow requestto isadapt 571,392it fieldsto andyour 11needs.1352 Gbytes(eg to add or remove some steps or Change the keywords below to adapt it to your needs.parameters etc) """ 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": "1/2/to3/324", "type": "pf", }) def ECMWF_reforecast_pf_sfc_request(hindcastDate, target): """ An A ECMWFreforecast, perturbed forecast, sfc request. TheChange costthe ofkeywords thisbelow requestto isadapt 383,040it fieldsto andyour 7needs.1 GB (eg to add or remove some steps Changeor the keywords below to adapt it to your needs.parameters etc) """ 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": "1/2/to3/324", "type": "pf", }) if __name__ == '__main__': retrieve_ECMWF_reforecast() |
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