.. _number_density:

Number Density
^^^^^^^^^^^^^^

Ozone and nitrogen profiles are given in units of mol/m\ :sup:`3`. To convert them to number density
profiles with units of molecules per cm\ :sup:`-3`, multiply by 6.02214076e+17.

.. code-block:: python

    import os
    import xarray as xr
    import matplotlib.pyplot as plt

    # load data and set time as the dimension
    v7_folder = r'path\to\v7_data'
    data = xr.open_mfdataset(os.path.join(v7_folder, '*.nc'))
    data = data.swap_dims({'profile_id': 'time'})

    avogadro_factor = o3.ozone_concentration.multiplication_factor_to_convert_to_molecules_percm3
    data['ozone_number_density'] = data['ozone_concentration'] * avogadro_factor
    data.ozone_number_density.where((data.latitude < 10) & (data.latitude > -10))\
                             .resample(time='MS').mean(dim='time')\
                             .plot.contourf(x='time', figsize=[9, 4])

.. image:: ../images/o3_number_density.png
   :align: center