Commercial TV doppler radars question

[Jeremy Miller]

Hi folks,

I was thinking this morning on how much technology in the field of meteorology has progressed. Especially in respect to weather radar. I am curious does anyone know when the first commercial tv doppler radars were used on air live?. There is a brief momment in "the day of the killer tornadoes" about the Xenia Ohio tornado. It showed the TV meteorologist looking at what appeared to me to be a pre-WSR 57 radar with the rotational sweep. Was this a commcerial radar?

What are your opinions on commcerial radar?. Do some tv stations over hype or make thier radars capabilities sound greater than it actually is?. How, do they compare to wsr-88D in detecting precipitation and velocities and the suit of products available from 88D?. I do knew that some commcerial radars anntenuate badly.

What did the TV stations use for radar to show thier viewers before computers and commcerial radars became previlant?.
Now with the wide spread use of tv doppler radars, does anyone think this may cause the public to overestimate the capabilities or reliability of commcerial doppler radar units?. I've seen many commcerials locally and on youtube.com for promos on the in house doppler units and it seems the promo sensationalizes the radar. IE: (The most accurate and powerful private doppler radar in the area!) or " Super Live Doppler radar is most reliable compared to nws radars that take several minutes to update, while super live doppler radar pin points the storm as it is happening now!"

I personally use and prefer the 88D over private tv doppler radars, as I believe (not quite sure) that the WSR-88D is more powerful than what is allowed for commcerial private doppler units. I use weathertap studio and able to access all the products available to the public and get updated imagery every 6 minutes. Unlike TV doppler radar imagery on tv station websites update every 10 minutes some update sooner, however you only see base reflectivity. However, that is only meant for the general public to see where its precitating. So they can prepare appropriately for thier daily activities.

I am interested in hearing (reading rather) what is thought of commcerial radars from those hear.

Take care, Godbless and stay safe out there!

Jeremy

 

[Mike Smith]

To take your questions/comments in order...

There were zero television broadcasts of NWS radars pre-WSR-57. There were several hundred TV hookups to the -57.

Do some stations overhype? Yes. So does the NWS, on occasion (i.e., the press release after the Enterprise tornado that claimed SPC forecast a "high risk" days before the tornado). It may be unfortunate, but it seems that hype is part of our society.

That said, most TV Dopplers do what they say they will do, some with higher resolution than the WSR-88D currently outputs. Yes, they show velocities and spectrum widths. The commercial radars can sample low level echoes more than 12 times as often as the -88D (3 rpm antenna rotation versus 4.1 min. volume scan; some TV radars can do 5 rpm), which is very valuable in tornado and rapidly changing situations.

Where the shortcoming can occur is in the training of the meteorologists who are intepreting that data. Like any other profession, some TV meteorologists are excellent, some are weak.

The first digitized TV color radar display was in summer, 1976, at KARD - TV, Wichita where I was working. Before, we put a black-and-white camera on a cathode ray tube (CRT) repeater scope and gave the audience a black and white radar image that faded rapidly. There was an edge-lighted glass map between the CRT and the camera that showed the state lines and major cities. Digitized, color radar was a huge improvement.

You lose me a bit here:

Now with the wide spread use of tv doppler radars, does anyone think this may cause the public to overestimate the capabilities or reliability of commcerial doppler radar units?. I've seen many commcerials locally and on youtube.com for promos on the in house doppler units and it seems the promo sensationalizes the radar. IE: (The most accurate and powerful private doppler radar in the area!) or " Super Live Doppler radar is most reliable compared to nws radars that take several minutes to update, while super live doppler radar pin points the storm as it is happening now!"

I personally use and prefer the 88D over private tv doppler radars, as I believe (not quite sure) that the WSR-88D is more powerful than what is allowed for commcerial private doppler units. I use weathertap studio and able to access all the products available to the public and get updated imagery every 6 minutes. Unlike TV doppler radar imagery on tv station websites update every 10 minutes some update sooner, however you only see base reflectivity. However, that is only meant for the general public to see where its precitating. So they can prepare appropriately for thier daily activities.

As long as the claim is accurate (i.e., the radar is the most powerful or if it does update 12 times more often than the NWS radar), I don't understand what your concern might be.

Right now, you see the Mac versus PC ads on the air. The purpose is to get people information that they can use to make an informed (assuming the info is accurate) choice between a Mac and PC (obviously, Apple wants you to choose Mac). What's wrong with a TV station accurately pointing out the differences between its radar and a competitor's?

There are private sector radars that are more "powerful" than the -88D, but power has relatively little to do with it. It is the sensitivity of the radar that is far more important as to how well it displays weather.

Television radars are "C" band (shorter wavelength). The -88D is "S" band. TV radars attenuate more (other factors equal) than the -88D.

There are strengths and weaknesses to the NWS volume scan approach and to the TV stations' more rapid view of the lower levels of the storm.

Hope this is helpful.

Mike

 

[John Diel]

I won't answer all of the questions presented here, but I'll stab at a few.

I remember back in the late 60's early 70's, watching KOAM out of Pittsburg, Ks. with a green scope radar. I have no idea what model it was, but I remember the "blobs" being called storms.

I also remember KTUL out of Tulsa with Don the weatherman, Bob Hower the News anchor and Gusty, the weather cartoon. I think that's where I saw my first color "doppler" radar.

TV Stations are in a very large competition for viewers. So if there Radar is named Bigger and Better than station XYZ, then they'll get the viewers (this is simplified, of course). This is especially true of the markets where severe weather is common. Every year there are "Weather Wars" in OKC between the three big stations. They all want your veiwership as that brings in more money.

Take a look at last years Million Watt Radar. (KFOR???) Do they really need a million watts of power? You could have some roast goose come Christmas time, but a million watts of power just to see clouds in the pan handle that you are viewing at the mid-level anyway? I mean really now. But that station pumped it up big time.

So, yeah, they pump it up.

Are they better than the WSR 88D radars? Possibly, Probably. TV Stations spend a lot of money with the makers of the radars to get the biggest, best and latest, so it stands to reason that the Government Low Bidder isn't going to be quite as up to date. The software packages are certainly much nicer than the WSR 88D in terms of "Viewer Friendly". They are designed to be placed on a TV screen and give the viewer something they can relate to. NOAA on the other hand, isn't quite as concerned about the general populace viewing and more geared to the Meteorologist who has an idea of what they're looking at.

TV Radar you see on the web is refreshed by what ever time constraint was placed by the web builder. With a "standard" doppler radar, you are still constrained by the time it takes to make a volume scan. That's why it's 6 minutes for NOAA. It takes that long for the radar to complete it's scan, process the data and get it out to the cutomers.

Now I don't know if the radars used by TV are showing real time (as close as they can get anyway) as the dish makes it's sweep or if they are rendering on the volume scan as NOAA.

My general thoughts are to each his own. If someone can understand a TV Radar better than NOAA radar, more power to them. Since I'm downloading the raw information from the NOAA servers and using a program to render and view that data, I prefer something I have some control over. That's one thing you don't get with TV Radar.

RDale can probably answer the rest better than I can. I believe he works with this stuff every day.

I think Mike and I were typing at the same time. Mike's more an authority than I am, so where we may conflict, take his word. Sheesh! my spelling is way off today!

 

[Jeremy Miller]

I would like to thank both of you for replying to my post.
Mike, I apologize for loosing you in part of my post. My
browser has been acting up lately. I would type a few sentances
and my browser would automaticaly go back one page. Then as I
forward to get back to typing my post it would be blank, I would
have to start over. Just trying to type this reply it has happened.
This is my third attempt at posting without having the page go back
one page, as if someone hit the back button on the browser.


I'll improve in my writing and constructing posts as time goes by. I've only been back to the forums for a couple days.

Again, thanks both of you for the replies. They were very informative and understandable. Very much appreciate. Thanks, Mike and John.

God bless and take care, stay safe!

Jeremy

 

[David Wagener]

Jeremy...

http://en.wikipedia.org/wiki/KWTV

Snip here, there use to be information on their own page before it merged with the Oklahoman's page.

Essentually KWTV was the first station to use a radar system for TV stations, installed in 1959. The first commercial radar was installed in 1981, along with the station in St. Pete.

 

[Morgan Palmer]

Rob will probably chime in with his feelings about this. At my station in East Texas, having live radars (we have two) is invaluable as most of our area is more-or-less in a hole between FWS, SHV, and HGX. In many cases, broadcast station radars are able to sample at a much lower elevation. ADD: I do not mean sample at a lower elevation side by side, but compared to the Tilt 1, many TV radars will end up seeing lower than the 88D at some given location.

The greatest advantage, esp. if your 88D site is nearby is continuous, real-time updates, usually programmed for lowest-level reflectivity. All broadcast radars, to my knowledge, can be cranked for any elevation, so RHI can be displayed, if desired... plus velocity.

Actually, in a super-critical tornado-development situation, real-time velocity is a big, big plus. Even the sub-5 minute update of VCP 12, I feel more comfortable looking at my local real-time velocity, sweep-by-sweep, esp. since the 88D is 8KFT or thereabouts over our central area.

As far as a volume scan of a storm, it can be done with TV station radar, but generally I think most stations rely on ingesting 88D L2 data to build that volume, just like in GR2AE. And that's probably best. We can get the volume look pretty quickly depending on the VCP the 88D sites are using, using our live radars to constantly update that lowest level. After all, that's what we're going to be showing to the viewer that vast majority of the time. Using 88D for volumetric display is usually plenty sufficient.

I will say that regardless of a station's radar, the 88D is of great use for many purposes for television, even if it's just behind the scenes storm diagnostics. Also, some TV radars attenuate more than others, and I think all attenuate to an extent that 88D will always be of great value.

Always, always, look for a timestamp on any web display of a TV station radar. Most stations' timestamps are accurate, but web servers etc can always be slow.

As far as "doppler wars", all I'll say is that TV weather is the most-watched part of most local TV news operations, and often the most heavily-promoted. The "weather wars" are here to stay.

mp

 

[Aaron Kennedy]

Most of the major points appear to have been hit... I'll just add that each system has its own place. A major disadvantages of the TV radars are the often small antenna size. To keep resolution up and costs down, these systems are not S-band like the WSR-88D and have a smaller wavelength (as Mike mentioned). End result is a system prone to attenuation. Not neccesarily a bad thing, just something someone needs to be aware of. The CASA radar network is pretty similar. Small dish, low power, small wavelength.

Another trend I often see associated with the high rotation rates of TV radars is noisy data. To get the high resolution data with a dish rotating rapidly, less pulses can be used for each bin of data. Snce our derived moments are related to pulse statistics, the less samples, the noisier the data. Typically, the stations smooth the data prior to displaying to viewers, however, so you won't notice. This is essentially the technique that will be employed by the WSR-88Ds within a few years to bump up resolution.

 

[Mike Smith]

A major disadvantages of the TV radars are the often small antenna size. To keep resolution up and costs down, these systems are not S-band like the WSR-88D and have a smaller wavelength (as Mike mentioned).

A couple of elaborations...

C-Band radar has wavelengths of approximately 5 cm. S-Band is approximately 10 cm. You only need half the size dish to get the same beamwidth with a C-band as opposed to an S. So, if you see a TV radar with a 12 ft. dish, you are getting the same beamwidth as 10 cm with a 24 ft. diameter dish.

Second, while a C band is less expensive due to the smaller dish, smaller radome and less expensive electronics, the reason there are zero S band TV radars is because the Federal Communications Commission will not license them to TV stations. I have no idea why this the case.

 

[Aaron Kennedy]

I didn't realize FCC dissallows S-band from TV stations. Perhaps this is to prevent inteference... although this wouldn't make much sense considering the TDWR FAA radars are also C-band. I think we can agree, however, that given a C-band and S-band system with the same beamwidth, the C-band would be cheaper given the smaller dish and apparatus needed to keep it in place.


Aaron

 

[Mike Smith]

Aaron,

Absolutely. One of the major cost reductions with "C" is the tower is less expensive because the antenna, pedestal and dome are smaller and weigh less for a given beamwidth. Less weight to support.

Mike

 

[Chris Nuttall]

Some TV stations also do a lot of oversampling and data processing with their own radars. I've seen that at several stations. That will lead to all sorts of things like anamolous propagation, second-trip echoes, side lobes, etc.

But, in my experience with TV, the combination of a local TV radar constantly scanning the lower levels (sector scans, full rotational, etc) used with L2 data from the 88D volume scans is the best combination. Esepcially with the lower level features, the TV mets can use both theis systems and the 88D to compare data. Very useful in determining if your data is "real" (i.e., actual rotation or downburst signature as opposed to a simple velocity fold).

 

[Morgan Palmer]

it was mentioned earlier about scan rates, and if there's an emergency situation where you might have fast moving tornadic storm in a populated area, most radars (I know mine does this) allows you to get azimuth limits, and you can get a back-and-forth sector sweep.

That can be especially helpful if you're going street-level.

As an aside, there was an interesting paper in the NWA journal earlier this year about the displacement of tornado reports from the radar signature. Especially when you have significantly tilted updrafts. Makes complete sense. Certainly something to remember when you go street-level with radar. We all know what is shown on radar may not always be what's happening at the ground.

mp