Using the GUI
=============

In order to be available for a broader audience, a GUI is also provided.
However, the GUI is not part of the pypi or conda package yet. You have to download it
mannually [from the git repo](https://gricad-gitlab.univ-grenoble-alpes.fr/webersa/pyPSCF/) (
[direct link](https://gricad-gitlab.univ-grenoble-alpes.fr/webersa/pyPSCF/raw/4df7205f742d1e0ba3c1d7faa68993e6fd9de4c3/GUI.pyw?inline=false) ).

There are several way to run the GUI, depending on what you are familiar with.

* From the terminal: navigate where the `GUI.pyw` file is, then enter
    
```bash
python3 GUI.pyw
```

* Using spyder/ipython

```py
%run GUI.pyw
```

* Graphically: simply double click on `GUI.pyw`. It may work. Maybe.

If it doesn't start, ensure that you are running python 3 and not python 2.

Initialization
--------------

The script looks for files in `parameters` named `localParamBackTraj.json`,
`localParamPSCF.json`, `locationStation.json`.
The package gives you the same three file, with a `_default.json` extension.
Copy and rename them in order to have the correct one in `parameters`:

```
parameters
├── SETUP_backTraj.CFG
├── localParamBackTraj.json
├── localParamBackTraj_default.json
├── localParamPSCF.json
├── localParamPSCF_default.json
├── locationStation.json
└── locationStation_default.json
```


Compute the back-trajectories
-----------------------------

### Hysplit

The back-trajectories have to be computed before running the PSCF script.
We use here the HYSPLIT program from the NOAA.
As HYSPLIT is a relatively big software with many option and configuration, we
developed a tool to compute the back trajectory in a easy way.  However, you
still need the HYSPLIT program. 
You can found it at [http://ready.arl.noaa.gov/HYSPLIT.php](http://ready.arl.noaa.gov/HYSPLIT.php).

### GUI description

![](../static/img/BackTrajGUI.png "BackTrajGui")

Once the script starts, you should see the window presented in the figure above.
Navigate to the `Back-trajectory` tab on the top if it is not already open.
This window presents the different parameters use to compute the back-trajectories.
Let's describe each of its field.

* Button frame

  * *Run Back-traj*: Save the parameters show in this tab in
    `parameters/localParamBackTraj.json` then compute the back-trajectories with
    theses parameters.
  * *Save BackTraj*: Save the parameters in the
    `parameters/localParamBackTraj.json` file without running the computation.
  * *Exit*: Quit the GUI without saving the parameters.

* *Meteo (GDAS) directory*: select the path to the GDAS files. GDAS is a file
  format uses to store meteorological data and are freely available from the
  [NOAA website](http://ready.arl.noaa.gov/archives.php) or 
  [ftp](ftp://arlftp.arlhq.noaa.gov/pub/archives/gdas1/).
* *Hysplit directory*: select the root path of the Hysplit directory's
  installation. It should contain the subdirectories *working, exec,
  script* etc.  
* *Output directory*: select where the back-trajectories files will be save.

* *Station frame*

  * *Station*: select the desired reference point. If the station is not in
    the list you have to add yourself the station in the
    `parameters/locationStation.json` file.
  * *Longitude/Latitude*: enter the longitude/latitude of the station. It should
    be updated automatically with the selection of the station.
  * *Altitude*: enter the altitude (in meter from the surface) of the
    back-trajectory starting point.