Replacement For Aging Doppler Radar Being Tested

longacre writes "Due to its limited range and slow scan times, the backbone of weather prediction in the US since the early 1990s, the NEXRAD radar system, is deeply flawed in the eyes of meteorologists. A new system being tested by researchers at the NOAA and four universities called the Collaborative Adaptive Sensing of the Atmosphere (CASA) network aims to fill the holes left by NEXRAD, using radar nodes piggybacked onto existing infrastructure, such as rooftops and cell towers. From the article: 'Based on faster and more comprehensive data collection, [Distributed Collaborative Adaptive Sensing] processing can refocus the CASA radars on a particularly interesting part of a storm (like an area that looks like it might develop a tornado) without losing track of an entire storm cell. "The system is continuously diagnosing the atmosphere and reallocating resources using wireless Internet as a backbone," says [the CASA team director].' Testing has begun in Oklahoma, Houston, and Puerto Rico, and initial installations could begin in 5 years."

Comments

Stealth hunter?

[AHuxley]

In many parts of the world this would be cover for a new passive radar system :-)
http://www.globalsecurity.org/org/news/2001/e20010619stealths.htm

Re:Stealth hunter?

[Rich0]

Such a system may not have much utility in a serious war. There are a few good reasons:

1. At best they give you an idea of where a target is - they're not suitable for guiding missles towards a target and shotting it down. That requires continuous illumination, which is hard when the illuminator doesn't easily get any feedback as to whether it is on target or not, and a missile can't see the reflections reliably.

2. It still depends on RF transmission to illuminate a target, but instead it uses "civilian" transmitters instead of military ones. I use the term civilian very loosly since if your cell phone network is used to illuminate military aircraft it is no longer a civilian technology. In a war with serious stakes an enemy would just fire anti-radiation missiles or artillery at anything that emits RF.

3. Civilian transmitters don't tend to have much in the way of infrastructure redundancy like military ones do. Blow up all the local power stations and batteries should be dead within a day or two, and blow up the fuel depots and even diesel generators aren't going to be much help - cell towers don't typically have huge fuel reserves like a military base would.

The main advantage of this sort of technology would be the ability to use super-cheap transmitters in combination with super-expensive receivers. Since the two are not in proximity it would be much easier to conceal the expensive detection equipment, and transmitters could be made more disposable.

In a less serious war you could rely on the reluctance of an enemy to destroy infrastructure that is primarily civilian in nature. However, in a less-serious war the enemy will probably not be so dependant on defeating your radar system - the only reason wars aren't fought seriously is because the conclusion is evident from the start.

Outdated information

[lpangelrob]

From the article...

Under the current NEXRAD Doppler system, a warning could be statewide, leading to false alarms for most of its residents.

No, not so much. The National Weather Service has started issuing storm-based (polygon-area based) warnings since August 2007. Prior to that, they were county-based warnings, which were a problem (Cook County, IL being about 50 miles tall by 40 miles wide, while average tornado widths are about 100 yards) but nowhere near the "statewide warning" the article claims.

Awful FAQ here: http://www.nws.noaa.gov/sbwarnings/FAQ/engage.html

Re:Outdated information

[morgan_greywolf]

At present USA is the only country in the world where planes have better Met radar capability and a better idea of what goes on in the atmosphere than ground staff even at some of the major airports.

In many areas of the USA, radar is currently being updated and upgraded. One of the most crucial technologies they are adding is

http://www.nssl.noaa.gov/research/radar/dualpol.php

, which bounces both horizontal and vertical waves simultaneously. Such radars can distinguish between a plane, a flock of birds and rain. Some say they are so accurate, they can actually measure a single drop of rain.

One TV news organization in our area already has one, and all of the NEXRADs that NWS uses are supposed to be replaced by like 2010.

Rednecks.

[retech]

I use a very tried and true method of weather prediction - Rednecks. If they are by water, there will be a flood. If they are in a trailer park, there will be a tornado. If they are on a hill - a mudslide. In the woods - forest fires.

We could save millions just watching the rednecks and avoiding those areas.

As a side note, I do enjoy the "seed-neck" on the news. You know the one, holding a beer with a stained tank top and in their boxers they always say stuff like: "We lost everythin' but we's gonna rebuild cuz this is our home." It's an aluminum can, how much needs to rebuilt?

Re:Rednecks.

[Anpheus]

It's still property, it's still their home.

And they still lost it.

Re:Rednecks.

[whereareweheadedto]

Very true. It's funny to make fun of rednecks, but when it comes to tragedy, they are still people. Unless they really make the disaster bigger, than it should be, due to their actions.

Re:Rednecks.

[oodaloop]

Well, when you're poor there aren't many great options of where to live. I'm sure if they could afford better real estate, they would move. When I was poor I lived in an apt near an airport because it was all I could afford. If all I could afford in my area was a trailer in a tornado zone, well then I guess that's where I'd live.

Re:Rednecks.

[oodaloop]

I'M on a high horse? For what, pointing out how poor I've been? You're blaming the victim, calling them stupid for living where they do, making fun of the way they talk, discounting all the hardship and turmoil theses people go through, and I'M on a high horse?

Re:Rednecks.

[baldass_newbie]

Why don't you pay for the general lack of intelligence and house these people?

I do. I'm a taxpayer. I also pay for their insurance claims since I live in a low-risk area. Plus I give to charity.
So what's your point, other than you like to ridicule rednecks who have suffered in a disaster?

Re:Rednecks.

[Talderas]

Build below sea-level in a hurricane region and near a river delta, expect a city to get flooded.

Accoustic detection- listen for

[Anonymous Coward]

The flying cows.

Re:Accoustic detection- listen for

[hcdejong]

That's why it's called "doppler": they detect the frequency shift in the "mooooooo"...

Re:Wireless Internet?

[lufo]

Not necessarily... just anything that could lose connectivity under severe weather condition.

Slow

[Wowsers]

Suppose that doppler radar is slow, and that it takes 5 seconds for it to do a 360 degree sweep. Is a faster system going to improve the generally rubbish weather forecasts of "it might rain today"?

Re:Slow

[oodaloop]

I think we'll see what's going on now with more fidelity, but weather prediction is still limited by chaos. Weather is sensitive to initial starting conditions, so no matter how well we know those starting conditions (today's weather), we will not be able to predict future weather more than about 10 days out with any kind of fidelity. We've also noticed that some weather patterns are more chaotic than others. You may notice sometimes they say stuff like, "The hurricane will make landfall tomorrow morning at 2am here." And sometimes they say, "We really don't know what this storm is going to do. It could land tonight or blow north. We'll have to see." What they do is run several simulations using variables a few decimal places off. Sometimes they all do the same thing, sometimes they vary so much there's no way to know what's going to happen. Adding new radar will not change the fact that weather is inherently chaotic and unpredictable.

Re:Slow

[clyde_cadiddlehopper]

In financial forecasting systems, the critical element is variance reporting. 'How wrong was yesterday's prediction?' leads to a sense of 'How much faith can you put in today's prediction?' Why, pray tell, is it that we NEVER see variance reports on the weather report?

Re:Slow

[giorgist]

At this point the best weather predictor is ...

"Tomorrow will be the same as today"

It beats the weather man by far and wide

G

Re:Slow

[CastrTroy]

The problem with weather forecasting is that they try to forecast way too far in advance. Checking out my local forecast, I see that they have until tuesday on the forecast. An entire week is too long to predict for weather. But they go further. There's now the 14 day trend. None of that is even worth looking at. I only trust the next day or two, and even that is a little fuzzy sometimes.

Re:Slow

[DarthBart]

The radars take several scans of the sky per "update".

They take scans at .5 degrees of dish elevation, 1.45 degrees, 2.4 degrees and 3.35 degrees. Those scans dissect the storm and look for rotation and intensity in different parts of the storm.

  Then the radars take an "echo tops" scan where the dish moves up and down to its limits while scanning horizontal. That lets the radars detect the total height of a storm, which gives another estimate of its strength.

So, its not just the dish spinning around in a single plane.

Re:Slow

[DeadChobi]

Well, if you're an atmospheric scientist doing research into weather, a faster system gives you finer resolution for studying the kind of time-dependent systems that they're interested in. Don't assume that this system won't ever be used to collect scientific data to analyze. One of the advantages of a faster sampling rate is that you can make better predictions based on your data. Essentially, you have a better idea of where some deterministic system has been, and so if you have a pretty good idea of the principles under which it works you can then get a better idea of where it's going. Hell, even if we don't have a technique for making better extrapolations in the face of higher resolution data, someone somewhere will come up with a way.

The other useful thing about this kind of data collection ability is that it can also be used to improve models, especially if it has a better resolution for storm cells than the current doppler system.

Re:Slow

[afidel]

If you don't know why weather radar needs to be faster then you have never been watching during an active thunderstorm. Sweep periods are quite slow in high resolution mode, they can speed things up but it costs significant resolution loss. What is needed is synthetic aperture radar where you can point a small array of antennas at the storm and get multiple different elevation readings simultaneously. We've had the technology for quite some time but it's just now coming down in price to where we can think of using it broadly for weather stations.

Re:Slow

[Hatta]

5 seconds? We had a tornado here in Omaha a couple weeks ago, and the sirens provided no warning because it hit during the 5 minute blind spot in the radar. On one pass it was a severe thunderstorm, on the next pass it was a tornado on the ground.

If they can't make the radar rotate faster, they should add more dishes to the same radar so it's looking in 2 or 3 directions at once.

Re:Slow

[tuxicle]

Surely you mean phased array radar, not synthetic aperture. The idea behind phased arrays is to improve overall volume scan times by allocating the limited energy budget of the radar as appropriate. Conventional radars, by design, will radiate an equal amount of energy over the entire scanned volume (over time). Phased arrays, given their ability to instantly (electronically) position the radar beam to any point in the sky, can allocate more energy to those areas that contain "interesting" targets (such as thunderstorms).

The DCAS part of CASA attempts to do this using multiple radars instead. So instead of each radar doing complete volume scans, a centralized system figures out where the "interesting" regions are, and directs the radars to scan only those sectors. The eventual plan is to use phased arrays at each radar node for even higher update rates.

Re:Better prediction means...

[Anonymous Coward]

luckily, the jam will resolve itself quickly through natural means

Title is misleading

[hcdejong]

because it suggests they'll use some new radar technology to replace doppler radar. In fact, they'll just install lots more radars (which can be cheap, short-range items) to improve coverage. According to the CASA site, they'll use modified marine navigation radars, ie the cheapest type of radar available, and these invariably are doppler radars.

Summary wrong in pretty much every claim

[lakshmanok]

The summary statement gets things wrong in pretty much every respect, so this is mainly for those folks who read the summary and assume it's a fair reflection of the story.

(1) CASA is not designed to replace the existing NEXRAD network. It is designed to supplement it. NEXRADs are designed for long-range surveillance. CASA radars see "under" the NEXRAD umbrella, up to 3km in height. The article makes this clear.

(2) NEXRAD scans are not slow. The fastest volume coverage patterns (VCPs) in NEXRAD, used in severe weather, scan the atmosphere every 4 minutes. The only thing faster is phased array radar and it is still experimental (See: http://www.oar.noaa.gov/spotlite/). CASA radars don't have volume scans, but their antennas are about the same speed as NEXRAD's.

(3) NEXRAD is not limited in range. It goes up to 460 km. A CASA radar's range is only 30 km. If any one thinks that NEXRAD is "deeply flawed" due to its limited range, they need to take it up with the Flat Earth Society (the range limitation is mostly because of the earth's curvature).

Please make sure you understand an article before sending it off to Slashdot!

Re:Better prediction means...

[catmistake]

Right now, NEXRAD affords a 15-20 minute heads up on tornados, and its not clear if that can be increased. Chaos Theory tells us that if we had a grid of sensors in the atmosphere 1 foot apart all around the globe and took a reading, the accuracy of predictions based on that reading would break down in about an hour. Certainly, tornado watches could be issued earlier, but tornado formation happens so quickly there is a limit to how early they could be predicted with any certainty, regardless of how accurate a radar reading.