extract_args.extract_args_firn
==============================

.. py:function:: extract_args.extract_args_firn(args)

   NumbaMinpack gives large performance boosts, but has very crude
   syntax which requires us to place all of our arguments to heateqn in
   a single vector. This function retrieves the relevant
   arrays from the "args" vector and separates them into
   physically-meaningful variables.

   :Parameters: **args** (*float64[:]*) -- Input vector of arguments. Generated using args_array from
                physics.solver.

   :returns: * **T** (*float64[:]*) -- Temperature of each vertical point. [K].
             * **Sfrac** (*float64[:]*) -- Solid fraction of each vertical point. [unitless]
             * **Lfrac** (*float64[:]*) -- Liquid fraction in each vertical point. [unitless]
             * **k_air** (*float64*) -- Thermal conductivity of air.
             * **k_water** (*float64*) -- Thermal conductivity of water.
             * **cp_air** (*float64*) -- Heat capacity of air.
             * **cp_water** (*float64*) -- Heat capacity of air.
             * **dt** (*float64*) -- Timestep. [s]
             * **dz** (*float64*) -- Change in firn height with respect to a step in vertical point [m]
             * **melt** (*Bool*) -- Flag which indicates whether melting has occurred.
             * **exposed_water** (*Bool*) -- Flag which describes whether there is exposed water at the surface.
             * **lid** (*Bool*) -- Flag which indicates whether there is a lid at the surface due to
               refreezing.
             * **lake** (*Bool*) -- Flag which indicates whether there is a lake present.
             * **lake_depth** (*float64*) -- Depth of the lake (in vertical points?)
             * **LW_in** (*float64*) -- Incoming longwave radiation. [W m^-2].
             * **SW_in** (*float64*) -- Incoming shortwave (solar) radiation. [W m^-2].
             * **T_air** (*float64*) -- Surface-layer air temperature. [K].
             * **p_air** (*float64*) -- Surface-layer air pressure. [hPa].
             * **T_dp** (*float64*) -- Dew-point temperature. [K].
             * **wind** (*float64*) -- Wind speed. [m s^-1].