8. Panoramic radar

8.1 Principle. Description

Weather radars known as "panoramic" radars can quantify precipitation intensity over circular areas centered on the radar.

A rotating satellite dish emits radio pulses at a very low frequency, enabling detection ranges of up to 200 km. The electromagnetic waves are reflected by water droplets encountered along their path. The reflection depends on the size and density of the hydrometeors encountered.

The antenna focuses the returned signals onto a receiver. The signals are digitized and processed by a computer associated with the radar, which provides a digital image representing the precipitation.

Each pixel in an image typically represents a geographical area between 1 and 4 km...