Rain, radiometry, and radar

A remote sensing system is proposed for quantitative operational measurement of the amount of liquid per unit volume in heavy rain. In particular, a 6-GHz radiometer in conjunction with a 10-cm wavelength radar is discussed. An experimental example involving a discrete heavy rain cell with a derived rainrate of 150 mm/h measured by a 6-GHz radiometer/3-GHz radar combination is given. The effect of clear air brightness temperatures, from oxygen and water vapor, on the 6-GHz radiometric rain measurements is analyzed, and an equation relating the 6-GHz brightness temperature from the rain to the radar backscattered power is derived. Design factors important in an operational observing system are also discussed