Computer Modeling Laboratory 9

Written report due: 20 April

Radar remote sensing of precipitation

Related material:
Lecture 12
S: 8.1-8.3, pp.408-410



Weather radar reflectivities are affected by rain, as well as by several other factors. Read a short tutorial and then take Quiz to test how well you can interpret radar images. Report your answers along with correct quiz's answers.


The National Weather Service operates the radar network to monitor the precipitation. See FAQs for more information.

  1. The radar reflectivity-rain rate relationship (called Z-R relationship) used operationally by the National Weather Service to calculate the rainfall rate is Z=300(Rr)^1.4. There is no precipitation in Atlanta today but plenty of heavy rain is the Boston area. Using today's radar data for Boston, calculate a maximum rain rate.
  2. On a log-log scale, plot Z-R relationships developed for stratiform rain and orographic rain (see Lecture 12). On your plot, indicate rain rates corresponding to radar reflectivities of 40 dBZ and 60 dBZ for each type of rain. Explain the differences. HINT: Think about size spectra of rain drops.
  3. Estimate an error in retrieved rain rates due to the underestimation of the measured radar signal by a relatively small amount, say 3 dBZ.