Coastal Radar Site and The Radars You Don't Hear About

Several of you have asked questions about the new coastal radar at Langley Hill. To address these inquiries I have created a web site dedicated to this new system (click on link to open):

http://www.atmos.washington.edu/~cliff/Langleyradar.html

If there is anything I am missing, let me know. The site will be regularly updated.

There some other local radars you might not know about. For example, at Seattle and at Westport there are two radar wind profilers. I have shown you the output of this machine quite a few times. Here is a sample:

The plot shows the winds and temperatures from the surface to 2-km in time for ONE location: Seattle Sand Point. Very different from radars, which give you lots of 3-D spatial information. But radars don't give you high resolution temperatures and winds above one point--something that can be very useful at times (like deciding how the freezing level is changing).

Here is what the device looks like (this is not the Seattle or Westport unit but ours look very similar):

The central unit is a Doppler radar with three beams: up and two perpenicular directions. Instead of tracking precipitation, they follow variations of atmospheric density. Doppler radars tell you whether the target is approaching or moving away, and it turns out that using the Doppler information from the three beams and a little trigonometry (that's right kids, trig has its uses!) one can figure out the winds with height. Pretty neat.

But there is more! You see those castle-like towers around the radar? Those are BIG speakers that emit powerful multi-frequency tones (you should hear my version of it!). This sound propagates into the atmosphere and disturbs the density variations aloft. The radar unit can then track the density variations and thus the sound waves. Since the speed of sound depends on temperature, this unit can determine the speed of the sound waves and thus temperature variations with height. The fancy name for this hardware is RASS--Radio Acoustic Sounding System.

In another blog I will talk about the Canadian and TV radars.....

Two nice days ahead, by the way. But don't worry, it won't last....