|Hail from a shower like the one on the radar plot shown above.
Vaisala’s HydroClass™ software takes conventional dual polarisation technology to a new level as it utilises observations made in both horizontal and vertical polarisation modes, formatting measurements as polarisation parameters that can be added to standard radar moments.
HydroClass™ is able to identify phenomena in real time at each observation point, exploring the full radar range on a sweep-by-sweep basis, every 10 to 15 seconds. This is a major advantage over conventional methods, which analyse vertical reflectivity structures and have a latency of up to 15 minutes for full-volume scans.
Classification results are presented by labelling each bin with the hydrometeor class most compatible with the observations in question. A threshold parameter is used to specify bins for which the class is ambiguous, such as non-meteorological targets.
Key application areas for Vaisala’s new dual-polarisation weather radar units include:
- Hail detection
- Lightning hazard potential forecasting
- Highway snow removal
- Airport terminal operation
- Rain/snow line demarcation
- Melting height detection
- Weather modification for hail mitigation
- Insurance claims verification
- Chaff detection
- Hydrological modelling.
Why go for dual polarisation?
The reason why Vaisala was keen to go for dual polarisation was quite simple really: the technique generates better-quality data that adds a new dimension to the accuracy of weather monitoring.
Vaisala’s C-band Doppler weather radar formats its dual polarisation measurements along three parameters – differential reflectivity (Zdr), specific differential phase (Kdp), and cross-channel correlation coefficient (Phv) – which are added to standard radar moments.
The additional information this generates enables scatter elements present in the atmosphere, such as rain, hail, and snow to be identified very precisely. Non-meteorological targets, such as clutter, insects, and chaff can also be isolated from weather-specific data and discarded.