Computer Modeling Laboratory 10

Written report due: 18 November

Radar remote sensing of precipitation

Related material:
Lecture 20,21
S: 8.1-8.3, pp.408-410



Weather radar reflectivity is affected by rain, as well as by several other factors. Read a short tutorial. Next, test how well you can interpret radar images. Below are several radar images from November 16, 1997. Identify the dominant echo-producer in each image.

Weather radar tutorial

For each of the four images select all that apply:

  • Ground Clutter
  • Anomalous Propogation
  • Other Transmitters
  • Birds and Insects
  • Clear Air
  • Precipitation

The National Weather Service operates the radar network to monitor 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 determine the rainfall rate is Z=300(Rr)1.4. Use measured radar reflectivity to determine a maximum rain rate in Atlanta. If there is no precipitation in Atlanta today use Boston radar data to determine a maximum rain rate.
  2. On a log-log scale, plot Z-R relationships developed for stratiform rain and orographic rain (see Lecture 21). 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 that would be caused by underestimation of the measured radar signal by a relatively small amount, say 3 dBZ.