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In general it is organised, as a huge tree, with the indentation below, showing different levels down that tree:

• type of data (analysis, forecast, 4D analysis increments)level 
  •  date
    
    •  time
      
      • steps, origins (ie Centres), members
  • year
    
    • month
      • type of level (model level, pressure level, surface) dates, times, steps, levels, parameters (same tape file )
        

The idea is to request as much data as possible from the same tape file . The natural way to group requests would be:
all parameters, all levels, all time-steps, all dates of a month

Note the following:

1. 'all' means 'all' that the user wants. It doesn't have to be all parameters.
2. If a user is interested only on z500,  he may request more months in one go, since the overall request will not be so big.

  The best approach is to iterate over the dates and for each date iterate over the times. At this point you may wish to  check TIGGE availability.

• The objective of this example is to demonstrate how to iterate efficiently over some years, for a particular ERA interim request. You may wish to have a look on the  ERA interim availabilitydates (eg '2014-10-01' and '2014-11-01')  two requests  for 'perturbed forecast', 'pressure' and 'sfc' level, for TIGGE, ECMWF Center.
• It The request below can be used as a starting point,however you need to   please keep in mind that you have to adapt it to your needseg to set the keyword, values according to your requirements (eg add or remove "param", "levtype", "step" 'param', 'levtype', 'step' etc).
• In this way you can extend this example to download the whole ERA interim dataset. these requests to download more data or a longer period of TIGGE.

The most efficient way to organise your requests is per dates and times

ie select a set of 'dates' and 'times' and add  the 'steps', 'origins', 'levels' and 'parameters' that you need.

   It is not efficient to organise your requests You can use the variable target to organise the requested data in files as you wish. per parameter, per  origin  or per step. (eg to submit a different request per parameter or per origin for a list of dates)

#!/usr/bin/env python
import calendar
from ecmwfapi import ECMWFDataServer
server = ECMWFDataServer()
   
def retrieve_tigge_interimdata():
    """       
       A function to demonstrate how to iterate efficiently over all days and months,
dates = ['2014-10-01', '2014-11-01']
    times = ['00', '12']
    for date in dates:
         for time in times:
             target = 'ecmwf_sfc_%s_%s.grb' % (date, time)
             tigge_pf_sfc_request(date, time, target)
             target = 'ecmwf_pl_%s_%s.grb' % (date, time)
        for years 2014 and 2015 for a particular interim_request. 
 tigge_pf_pl_request(date, time, target)

def tigge_pf_pl_request(date, time, target):
    '''
       A TIGGE request for perturbed forecast, pressure level, ECMWF Center.
       Please note Youthat a cansubset extendof the number of years available data is requested below.
       Change the keywords below to adapt theit iteration to your needs. (ie to add more parameters, or numbers etc)
    '''
    server.retrieve({
        'class': 'ti',
  You can also use the variable 'targetdataset': to'tigge',
 organise the requested data in files as you wish.'date': date,
       In the example below the data are organised in files per day. (eg '2015-12-01.grb').
    """'expver': 'prod',
        'grid': '0.5/0.5',
        'levelist': '200/250/300/500/',
        'levtype': 'pl',
    yearStart = 2014    'number': '1/TO/10',
    yearEnd = 2015
    'origin': 'ecmf',
     monthStart = 1   'param': '130/131/132/133',
    monthEnd = 12
    'step': '0/TO/96/BY/12',
        'target': target,
        'time': time,
     for  year in list(range(yearStart, yearEnd + 1)):
'type': 'pf',
    })

def tigge_pf_sfc_request(date, time, target):
    '''
       A TIGGE request for month in list(range(monthStart, monthEnd + 1)):
 perturbed forecast, sfc, ECMWF Center.
       Please note that a subset of the available data is requested below.
       Change the keywords below to adapt it to your needs. (ie to add more parameters, or numbers etc)
    '''
    server.retrieve({
         'class': 'ti',
         'dataset': 'tigge',
         'date': date,
         'expver': 'prod',
    numberOfDays = calendar.monthrange(year, month)[1]
     'grid': '0.5/0.5',
         'levtype': 'sfc',
         'number': '1/TO/10',
         'origin': 'ecmf',
         'param': '146/147/151/165/166/167/168/176/177',
         'step': '0/TO/96/BY/12',
         'target': target,
      for day in list(range(numberOfDays)):
 'time': time,
         'type': 'pf',
        requestDate})

if __name__ == '%04d%02d%02d' % (__main__':
    retrieve_tigge_data()
                                          

• ECMWF Web API Home
• ERA interim TIGGE availabilityA brief description of ERA interim
• TIGGE Home