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Illustrations of model levels, model half levels and model layers
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Figure 1. An illustration of IFS model levels, showing | Figure 2. An illustration of IFS model levels, model half-levels and model layers. The pressure |
Geopotential on model levels
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We use a Python script to download the ERA5 data from the MARS catalogue using the CDS API. The procedure is:
- Copy the script below to a text editor on your computer
- Edit the date, type, step, time, grid and area in the script to meet your requirements
- Save the script (for example with the filename as 'get_data_geopotential_on_ml.py')
- Run the script
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#!/usr/bin/env python
import cdsapi
c = cdsapi.Client()
# data download specifications:
cls = "ea" # do not change
expver = "1" # do not change
levtype = "ml" # do not change
stream = "oper" # do not change
date = "2018-01-01" # date: Specify a single date as "2018-01-01" or a period as "2018-08-01/to/2018-01-31". For periods > 1 month see https://confluence.ecmwf.int/x/l7GqB
tp = "an" # type: Use "an" (analysis) unless you have a particular reason to use "fc" (forecast).
time = "00:00:00" # time: ERA5 data is hourly. Specify a single time as "00:00:00", or a range as "00:00:00/01:00:00/02:00:00" or "00:00:00/to/23:00:00/by/1".
c.retrieve('reanalysis-era5-complete', {
'class' : cls,
'date' : date,
'expver' : expver,
'levelist': '1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22/23/24/25/26/27/28/29/30/31/32/33/34/35/36/37/38/39/40/41/42/43/44/45/46/47/48/49/50/51/52/53/54/55/56/57/58/59/60/61/62/63/64/65/66/67/68/69/70/71/72/73/74/75/76/77/78/79/80/81/82/83/84/85/86/87/88/89/90/91/92/93/94/95/96/97/98/99/100/101/102/103/104/105/106/107/108/109/110/111/112/113/114/115/116/117/118/119/120/121/122/123/124/125/126/127/128/129/130/131/132/133/134/135/136/137', # For each of the 137 model levels
'levtype' : 'ml',
'param' : '130/133', # Temperature (t) and specific humidity (q)
'stream' : stream,
'time' : time,
'type' : tp,
'grid' : [1.0, 1.0], # Latitude/longitude grid: east-west (longitude) and north-south resolution (latitude). Default: 0.25 x 0.25
'area' : area, #example: [60, -10, 50, 2], # North, West, South, East. Default: global
}, 'tq_ml.grib')
c.retrieve('reanalysis-era5-complete', {
'class' : cls,
'date' : date,
'expver' : expver,
'levelist': '1', # Geopotential (z) and Logarithm of surface pressure (lnsp) are 2D fields, archived as model level 1
'levtype' : levtype,
'param' : '129/152', # Geopotential (z) and Logarithm of surface pressure (lnsp)
'stream' : stream,
'time' : time,
'type' : tp,
'grid' : [1.0, 1.0], # Latitude/longitude grid: east-west (longitude) and north-south resolution (latitude). Default: 0.25 x 0.25
'area' : area, #example: [60, -10, 50, 2], # North, West, South, East. Default: global
}, 'zlnsp_ml.grib')
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- Copy the script below to a text editor on your computer
- Edit the date, type, step, time and grid in the script to meet your requirements. Note the 'area' keyword can also be used. The output filename can be modified accordingly.
- Save the script (for example with the filename as 'get_data.py')
- Run the script i.e.
python3 get_data.py
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# **************************** LICENSE START ***********************************
#
# Copyright 2022 ECMWF. This software is distributed under the terms
# of the Apache License version 2.0. In applying this license, ECMWF does not
# waive the privileges and immunities granted to it by virtue of its status as
# an Intergovernmental Organization or submit itself to any jurisdiction.
#
# ***************************** LICENSE END ************************************
import cdsapi
c = cdsapi.Client()
c.retrieve('reanalysis-era5-complete', {
'class': 'ea',
'date': '2021-01-01',
'expver': '1',
'levelist':'1/to/137',
'levtype': 'ml',
'param': '130/152',
'step': '0',
'stream': 'oper',
'time': '00/to/06/by/1',
'type': 'an',
'grid': '1.0/1.0'
}, 'output_00_06_130_152_1x1.grib') |
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