To demonstrate a basic understanding of the theory and major output of conventional, Doppler, and polarimetric weather radar systems. Although some of this material will be covered during the on-line lectures and the classroom part of the course, the majority will be done through the self-study modules.

Objective 1.1

Explain the basics of conventional and Doppler radar systems providing data to Canadian Weather Offices.

Enabling Objectives

1. Describe the historical development of weather radar and types of radars - pulse, frequency modulated continuous-wave radar (fmcw), precipitation occurrence sensor system (poss), vertically pointing, satellite, wind profiler, doppler, and polarimetric.

2. Describe the distribution of radars in Canada and in U.S. border stations that provide data to Canada

3. Describe and explain the radar equation for a pulsed weather surveillance radar

4. Describe the main components of a radar (antenna, pedestal, transmitter, modulation, receiver, signal processor, etc). Note differences in the hardware/technology used in Canada, the US, CASA, or other wavelengths.

5. Describe the main characteristics of the antenna in terms of:

· Size

· Beamwidth

· Shape

· Feedhorn

· Sidelobes

· Tradeoffs

6. Describe the differences between the transmitter used in U.S/McGill radars with those in MSC radars in terms of:

· wavelength

· tradeoffs

7. Describe the process of pulse modulation and sampling with respect to:

· pulse length

· beamwidth smearing


· range-velocity tradeoff

8. Describe the main characteristics of the receiver in terms of:

· minimum detectable signal

· averaging – why, range, and azimuthal averaging

· signal statistics

· the US super-resolution

9. Describe the main characteristics of the signal processor in terms of:

· ground clutter removal

· US vs Canada

· pulse pair vs FFT,

· configuration

· data quality issues

· dual-polarization considerations

10. Explain the Doppler effect

11. Explain what velocity folding is and why it occurs

12. Describe the representation of true wind velocity by its radial component

13. Describe the limitations of Doppler radar including

· unambiguous range

· second trip echoes

· maximum unambiguous velocity (Nyquist velocity)

14. Explain the Doppler dilemma

15. Describe how the Canadian radar system extends the range of the maximum unambiguous velocity

16. Discuss various scan strategies

· Canada vs US

· Synchronization

· data parameters

· Why do we use different scan strategies?

17. Explain anomalous propagation including the atmospheric conditions which lead to

· super-refraction

· sub-refraction

· ducting

· why does ground clutter twinkle?

18. Describe what causes the following radar artifacts and how you would identify each one

· attenuation

· partial beam filling

· beam blocking (terrain blocking, trees, towers, and buildings)

· beam spreading

· overshooting of the radar beam

· multi-trip echoes

· side lobes

· radome wetting

· sampling error due to cell motion

· variations in precipitation phase

· bright band effect

· variations in the drop size distribution

· anomalously-high intensities due to wet hail

· typical dBZ values - D dependence

· beam propagation as a function of elevation angle - beam height diagram

· virga

19. Describe the effects on the radar signal from the following non-meteorological targets

· obstacles and obstructions:

obvious targets: buildings, mountains

subtle targets: trains, highway traffic, etc.

· biological targets: birds, insects, etc.

· miscellaneous targets: chaff

· dBZ of birds, planes, etc.

20. Explain the method of relating reflectivities to rain/snowfall rates (Z-R and Z-S relationships)

21. Explain the process which produces a bright band in radar reflectivities

Objective 1.2

Explain the basics of polarimetric radar.

Enabling Objectives

1. Explain the difference between standard polarized radar and dual polarized radar

2. Understand the historical development of dual-polarized radar

3. Briefly explain how dual polarized radar can impact weather forecasts

· Improved estimation of rain and snow rates

· Discrimination of hail from rain and possibly gauging hail size

· Identification of precipitation in winter storms

· Identification of electrically active storms

· Identification of aircraft icing conditions

· Signatures for non-meteorological scatterers

Objective 1.3

Describe how the various radar algorithms work with an emphasis on their strengths and weaknesses.

Enabling Objectives

1. Describe the strengths and weaknesses of mosaic generation algorithms

2. Discuss signal processing algorithms such as

· doppler filtering of ground clutter

· point filters

3. Describe the different approaches used in the following:

· Cell Identification

· Cell Selection for Cell View

· Cell Tracking

· Cell Storm Assessment


· Wdraft using reflectivity

· Meso-cyclone

· Hail size, both the US and Australian algorithm

· Microburst detection

· Gust using velocity shear

· Cross-section algorithm

Objective 1.4

Describe the different radar products available in Canadian forecast offices and their use, including US radars that are used by Canadian forecasters.

Enabling Objectives

1. Describe how a volume scan is taken in Canada and in the US. Discuss the various scan strategies and their impacts on:

· Number of samples

· Number of elevations

· Azimuth rotation rate

· Volume scanning time

· Product processing and delivery

2. Explain what is configurable in determining the scan strategy and product processing and what is not.

3. Describe the following radar reflectivity products including an explanation of their use.

· PPI (Plan Position Indicator)

· CAPPI (Constant Altitude PPI)


· Echo top

· Vertical cross section

· 3HR PA (precipitation accumulation)

4. Describe the following summer severe weather products including an explanation of their use


· Max R

5. Describe the following radar products from the Doppler scan including an explanation of their use

· Radial Velocity


· Corrected Log Z

6. Explain how the US NIDS products differ from Canadian products.

7. Describe the following Unified Radar Processor ( URP) products including an explanation of their use:

· Summer composite (SUDDS)

· Winter composite (WIDDS)

· Multi-layer products for a single radar (SERF)

Objective 1.5

Describe how radar can be used to improve QPE estimates and forecasts.

Enabling Objectives

1. Describe how to calibrate a QPE estimates using radar data

2. Describe how to correct a QPE estimate using radar data

3. Describe the differences between the US and Canadian approaches

4. Describe how to improve QPE forecasts using radar data

Last modified: Tuesday, 18 September 2012, 8:38 AM