Sunday, January 16, 2011

Doppler Radar Doesn't Always 'Measure Up'

The above image was taken from the New Braunfels, TX doppler radar a few moments ago.  It depicts the radar's estimate of storm total rainfall from the rain event we've had over the past 3 days.  

If you believe the radar estimate, approximately 0.15 inch of rain fell at my home near Kyle, TX.  In fact, my official CoCoRaHS rain gauge shows that we've received 1.40 inches of rain since Friday.

What's the deal, you ask?  While the WSR-88D (which is 1988 technology, mind you) does a good job of estimating convective (thunderstorm-related) and other heavy rainfall events, it doesn't always handle the lighter stuff all that well (i.e., pro-longed periods of light rain or drizzle over an extended period of time).

Scientists at the National Severe Storms Laboratory (NSSL) in Norman, OK (the weather and weather radar capital of the universe) are currently experimenting with a new type of radar, called Phased Array.  Not only does that technology promise to improve precipitation estimates in all types of situations, but more importantly will likely lead to even earlier warning of severe and tornadic thunderstorms and other hazards.

Instead of sampling the atmosphere with one single radar beam every 4-7 minutes (as with the current radar system), phased array would sample the atmosphere every 20-30 seconds, and using multiple beams that can be focused on one particular storm or part of a storm for extended evaluation.

The technology is currently being evaluated at the National Weather Radar Testbed in Norman.  

Phased Array Radar in Norman, OK

Schematic of the Phased Array Radar

For more information on the exciting potential of the Phased Array radar in meteorology, go to the NSSL's fact page.

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