dB scale for the Reflectivity Field

  • dB, or log scale is used for the radar reflectivity field since the returned power to the radar can vary over 8 orders of magnitude!!!!
  • db= 10 log(x)
  • so receiver takes the log of the signal (in base 10)
  • for meteorological radars, typical dB units used are:

where Z = radar reflectivity (more on this later)

  • the dBZ unit is used extensively and varies over a range from -20 to 70 dBZ
  • In the old days, dBZ was turned into VIP (Video Integrator Processor) levels --->
VIP Level   corresponding dBZ   Precip Intensity
1   less than 30   light
2   30-40   moderate
3   40-45   heavy
4   45-50   very heavy
5   50-57   intense
6   greater than 57   extreme