The relationship between attenuation coefficient

k

and radar reflectivity factor

Z

as well as that between k

Zand rainfall rate

I

is influenced by the shape of precipitating raindrops and the orientation of their rotatory axes respect to the polarization direction of the incident radar wave. Provided that the orientation of rotatory axes of poly-disperse small spheroid particles is known

correctable thickness of radar echo for attenuation depends mainly on rainrate. The heavier the rainfall rate

the thinner the correctable thickness. For an 80mm/hour precipitation uniformly distributed along a radial direction

correctable thickness of radar echo is more than 120km for 5.6cm wavelength and about 50km for 3.2cm if correction algorithm R2or R3is used. Orientation information is critically important during attenuation correction. Right k-Zrelationship must be coupled with right orientation status.