This documentation shows how to use these python scripts to extract ECMWF ERA-Interim data and generate WINDFIELDS for running FLEXPART.
### Overview ###
To run FLEXPART with ECMWF ERA-Interim data, you first need to retrieve ECMWF ERA-Interim GRIB fields and generate FLEXPART WINDFIELDS to run FLEXPART.
The two main programs are called respectively `getEIdata.py` and `prepareFLEXPART.py`.
To get the usage of these programs, use `-h` option:
`getEIdata.py -h`
Optional arguments are mentionned in squared brackets.
*`getEIdata.py`
This program allows you to download ECMWF ERA-Interim data from ECMWF using [ecmwfapi](https://software.ecmwf.int/wiki/display/WEBAPI/ECMWF+Web+API+Home).
It requires `ecmwfapi` python library (see Requirements below). Check with your local IT group as it may be already available.
--area=area area defined as north/west/south/east with default
90.0/-179.0/-90.0/180.0
--outputdir=outputdir
root directory for storing output files
}}}
*`prepareFLEXPART.py`
This program allow you to generate FLEXPART WINDFIELDS (inputs for FLEXPART). It requires python interface to grib_api and `CONVERT2` program (located in `src` directory with instruction on how to compile it). You also need to provide a namelist for CONVERT2 (see test_1).
--inputdir=inputdir root directory for reading input files
--outputdir=outputdir
root directory for storing output files
`
### Requirements ###
| Python Support |
|----------------------:|
| python | [http://www.python.org](http://www.python.org) | We have use [python Anaconda](https://store.continuum.io/cshop/anaconda/) for our testings
| python-numpy | [http://www.numpy.org/](http://www.numpy.org/) | Not necessary if you have installed python Anaconda
| ecmwfapi | [https://software.ecmwf.int/wiki/display/WEBAPI/ECMWF+Web+API+Home](https://software.ecmwf.int/wiki/display/WEBAPI/ECMWF+Web+API+Home) | You also need to install your API key (as explained in the documentation)
| Utilities |
|----------------------:|
| grib-api | [https://software.ecmwf.int/wiki/display/GRIB/Home](https://software.ecmwf.int/wiki/display/GRIB/Home) | Make sure you install GRIB-API with JPEG support and python GRIB-API.
|----------------------:|
| FLEXPART programs | to run these programs (prepareFLEXPART.py), you need to compile CONVERT2 program (located in preproc/src). See separate README file to get instructions on how to compile this code.
|----------------------:|
### Installation ###
* Environment
At UIO, Red Hat 6 Linux systems (64 bits) were used for testing. We use the [Module package](http://modules.sourceforge.net/) to set-up user environment.
* Getting the source code
In the directory of your choice:
`
git clone git@bitbucket.org:flexpart/flexpart.git
`
This command will create a subdirectory called flexpart: it contains the latest FLEXPART version.
Set then environment variable `FLEXPART_HOME`:
** Korn-shell or Bash users:
`
cd flexpart
export FLEXPART_HOME=$PWD
`
** C-shell users:
`
cd flexpart
setenv FLEXPART_HOME=$PWD
`
* Installation
Make sure your first generate `CONVERT2` program (see separate instructions in `preproc/src`).
Users need to be able to execute prepareFLEXPART.py and getEIdata.py so make sure they have the correct unix permissions:
`
cd preproc/python
chmod uog+rx getEIdata.py prepareFLEXPART.py
`
These two programs must be in the user PATH. At UIO this is done automatically when loading flexpart. If not, you would need to do the following:
** Korn-shell or Bash users:
`
export PATH=$FLEXPART_HOME/preproc/python:$PATH
`
** C-shell users:
`
setenv PATH $FLEXPART_HOME/preproc/python:$PATH
`
Where `$FLEXPART_HOME` is the directory where FLEXPART
* Testing your installation
First check that grib-api python interface is correctly installed on your platform:
`
python
>>> from gribapi import *
>>>
`
Use `CTRL-D` to quit python.
Then check that `ecmwfapi` is properly installed:
`
python
>>> from ecmwfapi import *
>>>
`
If the two previous tests were successful, you can run `tests/preproc` (See separate instructions in `tests/preproc`).
If any of these two tests fail, this probably means that either `ecmwfapi` or `grib-api` have not been installed properly.
