STORM2K

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

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

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

Janie2006 wrote: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

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

Thanks so much wxman57!

WJS3

Cool, thanks wjs3 for pointing me to this thread.

No sweat!