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download_CAMS_daily.py
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README.md

download_CAMS

This tool is designed to download daily CAMS near-real-time forecast products from ECMWF. Otherwise, the graphical interface provided by ECMWF is available here: http://apps.ecmwf.int/datasets/data/macc-nrealtime/levtype=sfc/

The tool downloads several types of fields :

  • the Aerosol Optical Thickness AOT, for 5 types of aerosols, which are stored in the AOT file
  • the mixing ratios of each aerosol types as a function of altitude (expressed as model levels), stored in MR file
  • the Relative Humidity as a function of altitude expressed in pressure levels, stored in the RH file.

These files are available currently twice a day, and some of the aprameters are only availble as a 3 hour forecast, and not an analysis. The files are downloaded in netCDF format and look like this:

CAMS_AOT_yyyymmdd_UTC_hhmm.nc
CAMS_MR_yyyymmdd_UTC_hhmm.nc
CAMS_RH_yyyymmdd_UTC_hhmm.nc

The files are then converted in one archive using the Earth Explorer format, which was selected as the standard format for MAJA external data.

Configuration

{
"url" : "https://api.ecmwf.int/v1",
"key" : "your_key",
"email" : "your_email_address"
}

Example

python download_CAMS_daily.py -d 20180101 -f 20180102 -w /path/to/my/CAMSfolderNetCDF -a /path/to/my/CAMSfolderNetDBL

Parameters

The user can choose the following parameters with the command line:

  • w: where CAMS files will be stored

  • d,f: min/max range of dates to download

  • w: path to folder where netcdf data are stored (can be considered as a temporary file)

  • a: path to folder where DBL/HDR files are stored

  • k: to keep the netcdf files

  • p: The platform identifier

Other parameters could be accessed within the code :

  • step: forecast step in hours (default 3, ony value available so far)

  • type of file to download: surface, pressure or model (default all)

  • name of output files

  • grid: spatial resolution of downloaded files

  • format: grib or netcdf

Info on downloaded files

  • Surface files: Aerosol Optical Thickness (AOT) at 550 nm for the five aerosol models (BlackCarbon, Dust, Sulfate, SeaSalt and OrganicMatter).
Variable name	  Description
suaod550	  Sulphate Aerosol Optical Depth at 550nm
bcaod550	  BlackCarbon Aerosol Optical Depth at 550nm
ssaod550	  SeaSalt Aerosol Optical Depth at 550nm
duaod550	  Dust Aerosol Optical Depth at 550nm
omaod550	  OrganicMatter Aerosol Optical Depth at 550nm

From 2019/07/10 onwards, the format changed. The follwing AOT models were added:

Variable name     Description
niaod550          Nitrate Aerosol Optical Depth at 550nm
amaod550          Ammonium Aerosol Optical Depth at 550nm
  • Model files: mass Mixing Ratios (MR: expressed in kg of aerosol per kg of dry air [kg/kg]) of the aerosol models at 60 different altitude levels (model levels).
Variable name	  Description
aermr01	 	  Sea Salt Aerosol (0.03 - 0.5 um) Mixing Ratio
aermr02		  Sea Salt Aerosol (0.5 - 5 um) Mixing Ratio
aermr03		  Sea Salt Aerosol (5 - 20 um) Mixing Ratio
aermr04		  Dust Aerosol (0.03 - 0.55 um) Mixing Ratio
aermr05		  Dust Aerosol (0.55 - 0.9 um) Mixing Ratio
aermr06		  Dust Aerosol (0.9 - 20 um) Mixing Ratio
aermr07		  Hydrophobic Organic Matter Aerosol Mixing Ratio
aermr08		  Hydrophilic Organic Matter Aerosol Mixing Ratio
aermr09		  Hydrophobic Black Carbon Aerosol Mixing Ratio
aermr10		  Hydrophilic Black Carbon Aerosol Mixing Ratio
aermr11		  Sulphate Aerosol Mixing Ratio

From 2019/07/10 onwards, the format changed. The follwing mixing ratios were added:

Variable name     Description
aermr16           Nitrate fine mode aerosol mass mixing ratio
aermr17           Nitrate coarse mode aerosol mass mixing ratio
aermr18           Ammonium aerosol mass mixing ratio
  • Pressure files: Relative Humidity (RH: expressed in %) at 22 different altitude levels (pressure levels).
Variable name	  Description
r	 	  Relative Humidity

Information about these variables can also be found at http://atmosphere.copernicus.eu/ftp-access-global-data under the “Forecast surface parameters” and “Forecast model level parameters” sections, or at http://apps.ecmwf.int/codes/grib/param-db/