A Radar Rainfall Contouring Device

Abstract

This paper describes a device that indicates rainfall contour lines on radar scopes. For this purpose a range correcting signal γ, a signal K₁γ correcting atmospheric gases attenuation, a signal K₂R^αdγ correcting for attenuation by intervening rain and predetermined B, β signals which show the raindrop characteristics, are compensated for the input signal Pγ which is reflected from the rainfall. After the resultant signals are selected by a predetermined level which corresponds to a certain rainfall, the selected signals are presented on the PPI or the Rill scope as rainfall contours.
It is convenient to use Pγ, γ and B in the logarithmic unit for the circuit construction and the rainfall measurements will range over 60dB.
A mechanism which carries out level selections is added to this device. As the mechanism is constructed so as to synchronize with the radar antenna rotation, the iso patterns are automatically photographed by a 35 mm camera. It is also possible to skip certain levels freely for effective photographing.
Comparisons between rain gages and this device show pretty good agreement, by correcting for the attenuation by intervening rain. But the attenuation will be one of the very important causes of the errors in case we use a 3.2 cm wavelength radar.