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.
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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:
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Best practise to iterate over all hindcastDates of several hindcastYears for ECMWF
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for hindcastYear in hindcastYears |
Web-API examples:
An ECMWF reforecast request for all the available hindcastDates
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organise 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 = "2015-12-03" # 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 to iterateretrieve efficiently over all hindcastDays hindcastDates for a particular ECMWF reforecast model version. Change the variables below to adapt the iterationrequest to your needs """ # Please #Please note: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_%_%s.grb" % (origin, "pfpl", modelVersionDate) ECMWF_reforecast_pf_pl_request("/".join(hindcastDates), pfplTarget) # #Step 5Step 2: Get all the available perturbed forecast, surface data pfsfcTarget = "%s_%s_%_%s.grb" % (origin, "pfsfc", modelVersionDate) ECMWF_reforecast_pf_sfc_request("/".join(hindcastDates), pfsfcTarget) def ECMWF_reforecast_pf_pl_request(hindcastDate, target): """ AAn ECMWF reforecast, perturbed forecast, pressure level, request. The cost of this request is fields and Gbytes Change the keywords below to adapt it to your needs. (eg to add or remove some steps or parameters etc) """ server.retrieve({ "class": "s2", "dataset": "s2s", "date": modelVersionDate, "expver": "prod", "hdate": hindcastDates, "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/768/by/24", "stream": "enfh", "target": target, "time": "00", "number": "1/2/3/4", "type": "pf", }) def ECMWF_reforecast_pf_sfc_request(hindcastDate, target): """ AAn 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": "1/33/34/59/121/122/134/136/146/147/151/165/166/167/168/169/175/176/177/179/180/181/235", "step": "24/to/744/by/24", "stream": "enfh", "target": target, "time": "00", "number": "1/2/3/4", "type": "pf", }) if __name__ == '__main__': retrieve_ECMWF_reforecast() |
Useful links
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