Terminal Doppler Weather Radar

Terminal Doppler Weather Radar (TDWR) is a Doppler weather radar system with a three-dimensional "pencil beam" used primarily for the detection of hazardous wind shear conditions, precipitation, and winds aloft on and near major airports situated in climates with great exposure to thunderstorms in the United States.

[1] As of 2011, all were in-service with 45 operational radars, some covering multiple airports in major metropolitan locations, across the United States & Puerto Rico.

[4][5] Funded by the United States Federal Aviation Administration (FAA), TDWR technology was developed in the early 1990s at Lincoln Laboratory, part of the Massachusetts Institute of Technology, to assist air traffic controllers by providing real-time wind shear detection and high-resolution precipitation data.

[6] The primary advantage of TDWRs over previous weather radars is that it has a finer range resolution—meaning it can see smaller areas of the atmosphere.

[1] The reason for the resolution is that the TDWR has a narrower beam than traditional radar systems, and that it uses a set of algorithms to reduce ground clutter.

[6] TDWR uses a carrier wave in the frequency band of 5600–5650 MHz (5 cm wavelength), with a narrow beam and angular resolution of 0.5 degrees, and has a peak power of 250 kW.

In the case of the TDWR, this means the velocity of precipitations moving at a speed beyond 30 knots (35 mph; 56 km/h) away or toward the radar will be analyzed incorrectly because of aliasing.

It is working in 2009 on better filtering of non-weather echoes, better dealiasing algorithms of velocities, techniques to extract the horizontal component of the wind field from one or multiple radars.