Abstract

We have shown that path-averaged rain rates can be obtained from the raindrop-induced amplitude scintillations of a divergent laser beam (spherical wave case). We found that the rain rate obtained from a divergent beam is less sensitive to drop-size distribution than that from a collimated beam. However, the path-weighting function is heavily weighted toward the receiving end in the spherical wave case, whereas in the plane wave case, it is almost uniformly weighted along the optical path. The theory was confirmed by observations on two optical paths, one using a collimated beam on a 200-m path, the other using a divergent beam on a 1000-m path. The results for the longer path show a saturation effect for rain rates higher than 12 mm/h.

© 1980 Optical Society of America

Simplified optical path-averaged rain gauge

Ting-i Wang, K. B. Earnshaw, and R. S. Lawrence
Appl. Opt. 17(3) 384-390 (1978)

Laser rain gauge: near-field effect

Ting-i Wang, P. N. Kumar, and D. J. Fang
Appl. Opt. 22(24) 4008-4012 (1983)

Measurement of rain parameters by optical scintillation

Ting-i Wang, G. Lerfald, R. S. Lawrence, and S. F. Clifford
Appl. Opt. 16(8) 2236-2241 (1977)

Use of rainfall-induced optical scintillations to measure path-averaged rain parameters

Ting-i Wang and S. F. Clifford
J. Opt. Soc. Am. 65(8) 927-937 (1975)

Measurement of rain parameters by optical scintillation: computer simulation of the correlation method

Ting-i Wang and R. S. Lawrence
Appl. Opt. 16(12) 3176-3179 (1977)