Disdrometer

DD IN CCRES

Disdrometers (DD) measure the size distribution and falling velocity of precipitation at the surface. The measured drop size distribution is then used to derive other moments of the size distribution, such as reflectivity. For warm precipitation (rainfall), the radar reflectivity for any radar frequency can be derived reliably, using the appropriate dielectric factor and Mie scattering calculations for the specific radar frequency. The derived radar reflectivity during rain periods is then used to track the calibration of the cloud radar through comparison with the cloud radar reflectivity measured at the lowest reliable altitude range that the radar provides.