earthkit.meteo.thermo.array.saturation_ept
==========================================

.. py:function:: earthkit.meteo.thermo.array.saturation_ept(t, p, method='ifs')

   Compute the saturation equivalent potential temperature.

   :param t: Temperature (K)
   :type t: :class:`number` or :class:`array-like`
   :param p: Pressure (Pa)
   :type p: :class:`number` or :class:`array-like`
   :param method: Specifies the computation method. The possible values are: "ifs", "bolton35", "bolton39".
   :type method: :class:`str`, *optional*

   :returns: Saturation equivalent potential temperature (K)
   :rtype: :class:`number` or :class:`array-like`

   The actual computation is based on the ``method``:

   * "ifs": The formula is based on the equivalent potential temperature definition used
      in the IFS model [IFS-CY47R3-PhysicalProcesses]_ (see Chapter 6.11) :

       .. math::

           \Theta_{esat} = \Theta\; exp(\frac{L_{v}\; q_{sat}}{c_{pd}\; t})

   * "bolton35": Eq (35) from [Bolton1980]_ is used:

       .. math::

           \Theta_{e} = \Theta (\frac{10^{5}}{p})^{\kappa 0.28 w_{sat}}\; exp(\frac{2675\; w_{sat}}{t})

   * "bolton39": Eq (39) from [Bolton1980]_ is used:

       .. math::

           \Theta_{e} =
           t (\frac{10^{5}}{p-e_{sat}})^{\kappa} exp[(\frac{3036}{t} - 1.78)w_{sat}(1+0.448\; w_{sat})]

   where:

       * :math:`\Theta` is the :func:`potential_temperature`
       * :math:`e_{sat}` is the :func:`saturation_vapor_pressure`
       * :math:`q_{sat}` is the :func:`saturation_specific_humidity`
       * :math:`w_{sat}` is the :func:`saturation_mixing_ratio`
       * :math:`L_{v}` is the specific latent heat of vaporization (see :data:`earthkit.meteo.constants.Lv`)
       * :math:`c_{pd}` is the specific heat of dry air on constant pressure
         (see :data:`earthkit.meteo.constants.c_pd`)