Spectral analysis of rainfall induced scintillations on a 4.1 km 0.83 μm line-of-sight link over central London

Results for rainfall induced scintillations on a 4.1 km 0.83 μm link across central London are presented. The measurements were taken over a 12 month period between October 1993 and November 1994. Results for rainfall rates ranging from 0.13 to 6 mm/h show bumps above a spectral frequency of a few hertz. The bumps becoming less significant and move to higher frequencies as the rainfall rate increases. This feature of the spectra has been theoretically predicted by Wang and Clifford and is attributed to the interference fringes caused by the interaction of the incident wave and the spherical waves generated by scattering from the raindrops