Wind speed for ocean BPDF (in m/s) at present only available with
rte_solver montecarlo.
bpdf_tsang_u10 value
The BPDF model has been developed by Tsang1985.
The wind speed is the most important parameter affecting the ocean reflectance
matrix. The BPDF model also takes into account shadowing by surface waves.
The model has been implemented in a FORTRAN routine by Mishchenko
(http://www.giss.nasa.gov/staff/mmishchenko/brf/)
which has been included into libRadtran.