Ice Cloud Content from Radar Reflectivity

The ice equivalent radar reflectivity factor (Zi = 5.3Ze) is found from previous measurements to be related to the precipitation rate (R mm h−1) and ice mass content (M, g m−3) of ice crystal clouds by R = 0.067Zi0.804 and M = 0.037Zi0.696. Comparison with other empirical equations suggests that changes in the ice crystal size distribution accompanying the formation of precipitation particles begin to modify these relations within deep-ice clouds and lead to a different class of relations for snowfall. Accordingly, the above equations are considered valid for Zi ≲ 10 dBZ, and should be particularly appropriate for short-wavelength radar observations of cirrus clouds.