University of Bergen: Micro Rain Radar (MRR2)
This is a Micro Rain Radar (MRR2), manufactured by Meteorologische Messtechnik GmbH (Metek) installed onboard the NATO Research Vessel Alliance during the Iceland Greenland Seas Project.
The MRR2 is a frequency modulated (FM), continuous wave (CW) Radar (Radio Detection and Ranging) that obtains doppler spectral density at each range gate with a time resolution of 10 s. The terminal velocity of the precipitation targets (vT) is the primarily retrieved variable from these doppler spectral density observations. This instrument belongs to and was operated by University of Bergen.
The MRR2 transmits at a frequency of 24.230 GHz, which is modulated in a saw tooth pattern. This FM method enables the estimation of the target range in CW scanning mode. The height range configuration during the IGP campaign was set from 75 m to 2325 m at 31 range gates (range bin width is 125m). Due to near field effects, the first two range gates (75 m and 150 m) and due to noise the last range gate (2325 m) are discarded, leaving a range of 225 m to 2250 m. The MRR2 obtains doppler spectral density at each range gate with a time resolution of 10 s.
The terminal velocity of the precipitation targets (vT) is the primarily retrieved variable from these doppler spectral density observations. Additionally, drop size distribution and the corresponding moments, for example liquid water content (LWC), rain rate (RR) and Radar Reflectivity (Ze) are retrieved with post processing software, provided by Metek. The software only provides yields reasonable results for liquid precipitation, but erroneous vT estimates and insufficient noise removal can be present during snow events.
Maahn and Kollias (2012) provide a post processing software (IMProToo), that is able to improve the vT estimates, as well as the range gate estimate, by de-aliasing the doppler spectral density. Their software improves the Ze estimates from integrated doppler spectral density. The IGP campaign featured several snow events. Hence, the IMProTool was used in addition to the regular data post processing software by Metek. Both types of data files are included in the IGP dataset.