MSC Introductory Weather Radar Course

Reflectivity weighted average velocity of targets in a given volume sampled. Usually determined from a large number of successive pulses. Also called mean radial velocity.

A.K.A: MDS. In a receiver, the smallest input signal that will produce a detectable signal at the output. This value is a measure of receiver sensitivity.

Miscalibration influences compositing and produces biases in the rainfall rate estimates. It is difficult to correct precipitation attenuation because of it. An overestimate of Z produces an exponentially increasing error.

Example Image

A radar system in which the same antenna is used for transmission and reception of energy.

Description

2D-array of horizontal wind vectors, based on measurements of two doppler radars located typically less than 100 km from each other. .

Parameters

Product data quantity: array of speed (tenths of m/s and direction (degrees) of wind
Image size: number of arrays per row (# of columns) and per column (# of rows)
Coordinates of central point of the image
Array spacing: km
Upper limit altitude: m a.s.l.
Lower limit altitude: m a.s.l.
Maximum unambigious speed
Unfolding method used
Fallspeed correction method used if any

Notes

• The barbs cannot be used at area where the beams of the two radars are almost parallel. From this and other reasons, a quality indicator is essential.

Signal returns from a pulse other than the most recent. See also Range Folding.

When the radial component of target velocity exceeds one half wavelength (or 180 degrees) the measurement of the phase change between transmitted and received pulses is ambiguous. This results in radial velocity which is aliased. The velocity at which this occurs is the Nyquist Velocity.

V_N = PRF*λ/4

A combination of scanning strategies and product mixes tailored to one or more meteorological situations.

The precipitation process can be enhanced by the seeder-feeder mechanism. Convective cells aloft can produce large precipitation particles, falling through a lower cloud layer and growing at the expense of the water content at the lower cloud.

Radar pictures get infected by microwaves coming from other radars and microwave links. Most of the emitters can be discovered by pattern recognition from polar data.

Example Image