Description

The Micro Rain Radar (MRR) instrument is a Biral/Metek 24 GHz (K-band) continuous wave radar that derives profiles of drop size distributions and rain parameters from measured spectral power backscatter intensity. The MRR signal is transmitted vertically into the atmosphere where a small portion is scattered back to the antenna from rain drops or other forms of precipitation. Due to the falling velocity of the rain drops there is a frequency deviation between the transmitted and the received signal (Doppler frequency). This frequency is a measure of the falling velocity of the rain drops. Since drops with different diameters have different falling velocities the backscattered signal consists of a distribution of different Doppler frequencies. The spectral analysis of the received signal yields a power spectrum which is spread over a range of frequency lines corresponding to the Doppler frequencies of the signal. More information about the MRR instrument is available at Biral. 

Measurements

Measures drop size distributions in the range of 0.25 mm to 4.53 mm which covers the size of atmospheric precipitation drops. Larger drops in the atmosphere are affected by the air resistance as they fall and will split into smaller drops. From the drop size distribution other parameters are derived such as rain rates, liquid water content, Doppler velocity of falling drops, and path integrated attenuation. Data are provided as raw observations and time averaged values.

Applications

• Observation of the melting layer (bright band / freezing layer)
• Weather radar signal adjustment
• Cloud physics studies
• Nowcasting of precipitation events / Hydrology studies
• Chemistry changes through precipitation transport