geodata.wind.L_vph
==================

.. py:function:: geodata.wind.L_vph(ds)

   Obuhkov length using virtual potential heat flux term [1] (described in detail in SI [2])

   [1] Emeis, S. (2013). Wind Energy Meteorology. Retrieved from http://link.springer.com/10.1007/978-3-642-30523-8 (Note: error in eq 3.21)
   [2] Rose, S., & Apt, J. (2016). Quantifying sources of uncertainty in reanalysis derived wind speed. Renewable Energy, 94, 157–165.
           https://doi.org/10.1016/j.renene.2016.03.028