MSC Introductory Weather Radar Course

A rather shallow layer in the atmosphere through which vertical temperature and moisture gradients trap the radiating energy enabling the radar to detect targets at abnormally long ranges.

The ratio, usually expressed in decibels of maximum to the minimum signal which a system can handle. Most frequently used to describe limits of receivers or cathode ray tubes.

Description

The echo base product provides for each point on the surface, an estimate of the height of the lowest elevation of the first echo return that is above a reflectivity threshold.

Parameters

Product data quantity: altitude
Image size: number of pixels per row (# of columns) and per column (# of rows)
Pixel size: horizontal and vertical extension of the pixel in km
Reflectivity threshold: value in 0.1 dBZ
Level slicing method: list of values in 0.1 km a.s.l. or formula parameters (see section 7 in WD21_99)

Notes

• In areas where precipitation reaches ground or lowest measurement bin, this product shows undefined values.
• The quality of this product depends crucially on number of elevations in the polar volume.

Description

2D-map containing the highest altitude reaching a predefined reflectivity threshold inside the vertical column over each surface point.

Parameters

Product data quantity: altitude
Image size: number of pixels per row (# of columns) and per column (# of rows)
Pixel size: horizontal and vertical extension of the pixel in km
Reflectivity threshold: value in 0.1 dBZ
Level slicing method: list of values in 0.1 km a.s.l. or formula parameters (see section 7 in WD21_99)

Example image

The vertical pointing angle of the antenna; 0° is horizontal, 90° is vertical.

AKA Z_e. The concentration of uniformly distributed small (diameter one sixteenth wavelength or less) water particles which would return the amount of power received. Typically expressed as: dBZ = 10 log Z_e.

Flare echo is caused by the reflection of large hail in the mid levels of the storm. Radar scatters radiation toward the ground, after that it scatters back to hydrometeors, which then scatter some of the radiation back to the radar.

The number of recurrences of a period phenomenon per unit time. Electromagnetic energy is usually specified in hertz (Hz), which is a unit of frequency equal to one cycle per second.

A change in signal power, voltage or current. Usually applied to a change greater than one and expressed in decibels.

Gauge adjustment is a solution to problems connected with range effects, calibration level, and limited extent effects. Gauge adjustment is any procedure that makes partial changes in the characteristics of radar data in order to correspond radar derived measurements to the results given by gauge measurements.