.. _flexpart_plotting_cross_sections:

FLEXPART - Plotting cross sections
##################################
 
For preparations and running the simulation needed for this tutorial :ref:`click here ... <flexpart_forward_simulation>`

.. note::

  To start this tutorial please enter folder 'forward'.
  
The macro to plot a vertical cross section is 'plot_xs.mv'. We will see how this macro works.

First, we define the parameter and time step for the cross section then call :func:`flexpart_filter` to extract the data. 
The result is a fieldset with units of "kg m**-3", which we scale explicitly to "ng m**-3" units for plotting.

.. code-block:: python
  
  dIn="result_fwd/"
  inFile=dIn  & "conc_s001.grib"
  
  #Define parameter and step
  par="mdc" 
  step=48
  
  #Get fields for all levels for a given step
  g=flexpart_filter(source: inFile,
                    param: par,
                    levType: "hl", 
                    step: step)
  
  #Scale into ng/m3 units
  g=g*1E12
  
Next, we define the contouring:  
  
.. code-block:: python
  
  #The contour levels
  cont_list=[1,10,50,100,150,200,250,500,750,1000,2000,5000,7000]
  
  #Define contour shading
  conc_shade = mcont(
      legend  :   "on",
      contour :   "off",  
      contour_level_selection_type    :   "level_list",
      contour_level_list  : cont_list,
      contour_label   :   "off",
      contour_shade   :   "on",
      contour_shade_method    :   "area_fill",
      contour_shade_max_level_colour  :   "red",
      contour_shade_min_level_colour  :   "RGB(0.14,0.37,0.86)",
      contour_shade_colour_direction  :   "clockwise",    
      contour_method: "linear"
      )
  
Then, we define the cross section view along this line:

.. image:: /_static/flexpart_plotting_cross_sections/image2017-10-25_14-58-40.png
  
.. code-block:: python
  
  xs_view = mxsectview(
      bottom_level    :   0,
      top_level   :   16000,
      line    :   [63.31,-25,63.31,9]
      )
  
and finally generate the plot:  
  
.. code-block:: python
  
  plot(xs_view,g,conc_shade)
  
Having run the macro we will get a plot like this:

.. image:: /_static/flexpart_plotting_cross_sections/image2017-10-25_10-22-43.png