Abstract
The microwave attenuation produced by rain is calculated by taking account of the drop size distribution. Attenuation constants thus obtained are scattered about in some ranges, and the width of scatter is wider at X-band. The width at 10 mm /hr is respectively about 1.2, 6.2, 3.3, 0.9 db for the wave lengths of 8.6 mm,3.2 cm,5.6 cm,10cm, whereas the reflectivity Z varies by about 8 db for distribution of the same precipitation rate and the same drop size distribution.
As a result, the measurement of rainfall by the attenuation of Kband has a merit that it is less influenced by the drop size distribution.