MSC Introductory Weather Radar Course

A 10 centimetre wavelength radar.

The volume in which the radar data for one range bin are measured. Defined by the width of the radar beam (app. 1°) and half the length of the transmitted pulse. 1 µs pulses are 150 m deep, 2 µs pulses are 300 m deep.

Upper limit of dynamic range above which an increase in the input signal produces no detectable change in the output.

A volume scanning procedure designed for the surveillance of one or more particular meteorological phenomena.

Sea clutter is a specific form of spurious echo feature. The main reason of its formation is anomalous propagation of partial radar beam above water bodies, i.e. ducting. Sea clutter can be treated by identifying multiple modes of the reflictivity spectrum and then treating each mode differently.

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Problems caused in radar products

Second trip echos appear much weaker than real echos. Problem exists when PRF is big (thus r_max is small), and strong reflectivities appear high in the troposphere. SQI threshold removes second trip echos, because they are incoherent, but in this case we can lose valuable information.

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Problems caused in radar products

Doppler filter is useless when sidelobes hit the ship because of the movement of the ship. Ships and their sidelobe echos can be detected and removed using pattern recognition methods to polar data.

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Secondary energy maximum located outside the radar beam. Typically contains a small percentage of energy compared to the main lobe.

Problems caused in radar products

Secondary maxima of radar beam is called sidelobes. Echos caused by sidelobes are seen in wrong directions. Typically sidelobes are much weaker than the main one. So the problem exist if only it is very strong echo (hail, ship, ground clutter).

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Description

The Specific Differential Phase K_DP denotes the difference between the propagation constant for the horizontally and vertically polarized wave. In a homogeneous medium K_DP can be directly obtained from the differential phase shift φ_DP at two different locations.

Notes

• K_DP is only affected by anisotropic hydrometeors (rain) and therefore K_DP allows to discriminate between rain and frozen precipitation.