Radar beam heights

[wjs3]

Hi:

With some of the posts in the "Talkin' Tropics" forum and a recent microburst here in my area that was identified using doppler velocity

http://www.crh.noaa.gov/crnews/display_ ... 3&source=0

I am starting to become interested in using the tool more and more.

I know the basics of doppler velocities--for instance, I knw the difference between (and the basic applications of) storm-relative and base velocities. I've even used velocites while sailing (I was on an distance race and had an internet connection) to estimate windspeeds in incoming convection...but...

As I play with it more and more, I realize that I am missing an important part of the equation...how do I calculate the beam height? Assuming (and I'm assuming this) I can estimate how far away from the radar site the doppler velocity I am looking at is, how do I establish how high up it was?

For instance, when I used it while sailing (on Lake Michigan), I was far away from any radar sites. But I failed to take into account the beam height, so misestimated the winds we'd see.

I'm also interested in taking a look at more landfalling tropical cyclones to use Doppler velocity to validate/estimate intensity...anyway...

How do I calculate beam height?

Thanks

WJS3

[Aslkahuna]

There are usually tables around that give that information-might contact your nearest NWS WSFO to see if they can provide a copy or direct you to a site that has such information. Under typical atmospheric refraction conditions a radar beam through the troposphere describes an arc with a radius of 3/2 Earth radius but this depends a bit on wavelength and can be different under inversion or moisture inversion conditions.

Steve

[Janie2006]

The Refractive Index nomogram might be helpful....but most of the time I'm very happy to let the computer do the work!

[wjs3]

The Refractive Index nomogram might be helpful....but most of the time I'm very happy to let the computer do the work!

Yeah--I basically shoudl jsut get GRlevel 3 or some other radar analysis softare and let it do the plugging for me, I've decided.

Thanks

WJS3

[wxman57]

Here's an online beam height calculator. Just input beam elevation and distance to target:

http://www.wdtb.noaa.gov/tools/misc/bea ... width.html

[wjs3]

Thanks so much wxman57!

WJS3

[Rainband]

Cool, thanks wjs3 for pointing me to this thread.

[wjs3]

No sweat!