Interpretation of Basic Doppler Radar Imagery
You hear the term "Doppler radar" on TV all the time. A Doppler radar is capable of locating precipitation and also assessing its motion toward or away from the radar. The effect is much like the shift in pitch you hear as an ambulance moves toward you and than away from you.
Radar (also known as RAdio Detection And Ranging) has evolved significantly since its first use in weather during World War II.
The reflectivity portion of the radar signal tells meteorologists a lot about how much precipitation is falling, as well as something about the type of precipitation. The more radar energy that is reflected or scattered back to the radar, the higher the reflectivity. Colors are assigned to reflectivity ranges to make "reading the image" easier. Not surprisingly, thunderstorms, rain and snow appear quite differently on radar displays.
The Doppler portion of the radar information only shows the component of motion along radials from the radar. Any other motions will be missed.
|
Lets' assume that all the motion is from the east (as it was on September 5, 2004 over much of Florida's east coast). To the east of the radar, motion is shown as being TOWARD the radar (negative numbers, and coded in blues). To the west of the radar, motion is shown as going AWAY FROM the radar (yellows, reds and purples). In this case, nearly along the north-south radials, all motion is perpendicular, so there is no motion indicated toward or away from the radar.
Because of the tilt of radar and the curvature of the Earth, Doppler radar information is often more difficult to understand than reflectivity information.
With the advent of Doppler radar syatems, meteorologists have developed algorithms (step-by-step computerized mathematical procedures) to detect specific types of weather events like tornadoes, downbursts and hail. Your TV meteorologist may talk about "tornado vortex signatures" and other specific features that these high-tech weather instruments provide.
Getting in contact with How The WeatherworksTM...
Please send comments to webmaster@weatherworks.com.
This page was updated on September 5, 2004
Links to this page are encouraged.
However, all material at this web site, unless otherwise noted, is copyrighted by
How The WEATHERWORKSTM.
Any other reproduction or use of material in full or in part is prohibited without permission.
