Gain Control

Gain control is normally set in Calibrated mode, since this will provide return images that have been calibrated to represent a reference thunderstorm with accurate weather mode intensity depictions (Fig. 16). When setting the gain control to manual control and then moving the control from the Calibrated position, precipitation will be over or underrepresented. For this reason, it is best to leave the control in Calibrated mode for normal scanning.

While analyzing a return, and trying to determine the intensity of precipitation, it may be helpful to temporarily place the system into manual gain control, and then to adjust the control to the lowest level. This reduces the displayed intensity by 16 dBZ (Fig. 17), so that any remaining yellow returns would exceed the normal yellow threshold of 33 dBZ by 16 dBZ. These yellow returns would represent returns at minimum of 49 dBZ, indicating extreme precipitation and possibly large hail. A return showing in green in this case would have an actual return level of at least 39 dBZ, indicating moderate to heavy precipitation.

NOTE: The 16 color scale used in the GWX™  75 weather radar and GWX 80 eliminates the need for using gain control to determine return intensities.

KEY POINT: Always return the gain control to Calibrated mode when done exploring the intensities.

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