Algorithms

Particle Type Identification

Radar targets can be roughly defined by the polarimetric parameters. For example:

  1. Hail
    • High Z, lower ZDR, lower ρHV (when it's typically mixed with rain)
  2. Heavy rain
    • High Z, higher ZDR, high ρHV
  3. Non-meteorological targets
    • Areas of strong attenuation will have low Z but high KDP

Hydrometeor Classification Algorithms (HCA)

Exact boundaries between hydrometeor types are not crisp. There is overlap (i.e. they are "fuzzy"). ZDR cannot discriminate between rain and hail by itself; near-zero values of ZDR may suggest hail or drizzle/cloud droplets because they have nearly spherical shapes. Combining ZDR with Z helps because hail has a much larger reflectivity than drizzle/cloud droplets. 

Many existing algorithms are based on S-band radars, as the introduction of C-band polarimetric radars is very recent. Work on these is on-going.