Radar Application in Weather ForecastEECS 725Chao Jiang05/01/2015

Radar Application in Weather Forecast• Introduce to Weather Radar

• Typical Weather Radar Specification

• Limitation and Future Development

Weather Radar• Most of the weather radars are monostatic radars.

• Capable of detecting location of precipitation, calculating the motion of rain droplets, and its intensity.

• Usually operates in S-band and C-band.

• X-band weather radar is used only to detect nearby target, and Ka-band is used to research small-particle phenomenon.

• Ground, Airborne, and Spaceborne.

Introduce to WSR-88D Weather Radar• WSR-88D Network (160 Radars), operated by National Weather

Service

• Deployed across the US in the 1990s.

• Was the first radar able to detect particle motions.

• Operates in S-band (Frequency: 3.1 GHz; wavelength: 10.5 cm)

Basic Structure

Dual-polarization

Dual-polarization• Differentiating Rain and Snow.

• Detecting Hail Cores.

• Debris from Significant Tornadoes.

Limitations (Beam Height)• Due to the curvature of the Earth.

Limitations (Beam Height)

Limitations (Attenuation)• Occurs when large objects scatter most of the microwave.

• Makes the storms behind the large object appear weaker

Limitations (PRF constraints)• PRFmin = 2 ΔfD

• PRFmax = c/2Rmax

• Multiple scans at each angle

• Change PRF at the radar depending on the situation

Future development (Phased Array)• Consists of four stationary panels.

• Providing rapid scanning. Able to scan the sky in less than 1 minutes (more than 4 times faster than WSR-88D).

• Making the observation more accurate and reduce false alarms.

Phased Array Radar in Norman, Oklahoma

Reference• http://www.meteor.iastate.edu

• http://www.wdtb.noaa.gov

• http://www.nssl.noaa.gov