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## US Navy's High-Resolution Radar Can See Individual Raindrops In a Storm161

coondoggie writes "The U.S. Naval Research Laboratory (NRL) researchers said recently that a Navy very high-resolution Doppler radar can actually spot individual raindrops in a cloudburst, possibly paving the way for new weather monitoring applications that could better track or monitor weather and severe storms. According to an NRL release, the very high-resolution 'Mid-Course Radar' was used to retrieve information on the internal cloud flow and precipitation structure. The radar was previously used to track small debris shed from the NASA space shuttle missions during launch. 'Similar to the traces left behind on film by sub-atomic particles, researchers observed larger cloud particles leaving well-defined, nearly linear, radar reflectivity "streaks" which could be analyzed to infer their underlying properties,' NRL stated."
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## US Navy's High-Resolution Radar Can See Individual Raindrops In a Storm

• #### useful.... (Score:5, Funny)

on Friday June 29, 2012 @03:05AM (#40491005)
means you can avoid individual rain drops and keep your battleship dry.....
• #### Re: (Score:2)

At least you know what just hit you.

• #### Re: (Score:2)

Signal? Meet noise!

• #### Re: (Score:2)

Huge data set? Meet filtering and modern data-processing!

• #### Re: (Score:2)

Does this count as Big Data?
• #### Re: (Score:1)

by Anonymous Coward

.... not to mention keeping stealth aircraft out of the rain. Hey jim! There appears to be a load of raindrops travelling horizontally at Mach2, I wonder what that could be?

• #### Re:useful.... (Score:5, Insightful)

on Friday June 29, 2012 @09:34AM (#40493021) Homepage

What it means is stealth is now meaningless technology, paying megabucks for a stealth fighter is simply throwing the tax payers money away. Once you can accurately track moisture in the atmosphere, then tracking ex-stealth aircraft is simply a matter of searching for and pinpointing areas of the sky not behaving like other areas of the sky. Specifically those areas of the sky which show a disturbance of where the aircraft has been, contrails http://en.wikipedia.org/wiki/Contrail [wikipedia.org] and where the aircraft actually is shock and compression waves http://en.wikipedia.org/wiki/Shock_wave [wikipedia.org], even subsonic compression of the atmosphere by the passage of an aircraft substantially alters the amount of moisture in close proximity to the aircraft.

The US Navy might as well announce to the world, don't waste your money on the F35 or F22, what you want is a high durability aircraft. Stealth is utterly meaningless especially when the shape impacts durability and performance. Basically the only real defence is flying really low, as fast as possible and being the smallest target possible (cruise missile). Once you get above ground clutter, you'll announce your position, even if you stop and hover, your past passage will show up as well as your thrust plumes, jet or propeller.

No such thing as 'atmospheric' stealth no matter how advanced your technology unless of course you can jam or shut down the detection technology with even more 'advanced' technology (you can guess who I mean), the microchip being such an desirable target for at range energy fluctuations.

• #### Re: (Score:1, Funny)

by Anonymous Coward

Stealth aircraft use electrogravity tech to reduce their weight by a significant amount. You are incredibly misinformed.

• #### Re:useful.... (Score:4, Insightful)

on Friday June 29, 2012 @10:09AM (#40493447)

This may not yet be useful for real-time air defense purposes. The actual equipment my not be field mobile. Not to mention that getting data and analyzing over time it is one thing. Doing that while an aircraft comes at you at Mach 1.2 is a little different. Especially when it has a bomb or an anti-radiation missile with your name on it.

• #### Re: (Score:2)

How well will it work when radar jamming planes in the area jam this sensitive radar?

• #### Re: (Score:2)

For several reasons:
1) once radar is 'jammed' they know something is up and launch planes that have their own radar
2) They will quickly determine where the jamming is coming from, so you need aircraft entering before or at a different area.
3) Decoy
4) To evacuate the target area through another countries air space without alerting that country's general populace.

• #### Re: (Score:3)

high durability aircraft

The return of the A-10?

• #### Re:useful.... (Score:4, Insightful)

on Friday June 29, 2012 @11:47AM (#40494757)

Scientists could detect the individual particles because of a combination of the radar's3MW power, narrow 0.22 degree beamwidth, and an unprecedented range resolution as fine as 0.5m. This combination of radar attributes allows researchers to sample a volume of cloud about the size of a small bus (roughly 14 m3) when operating at a range of 2 km.

In other words, if you know where the stealth aircraft is to within the region of a small bus, this thing can find it!...so long as it isn't more than 2km away.

This radar is completely worthless in finding a stealth aircraft, or any aircraft at all for that matter. As presented, it doesn't even have any uses for that at all. Maybe you could extend it to that, but the narrow bandwidth and high power means it will be pretty well worthless for stealth detection.

• #### Re: (Score:2)

If you have a radar that is sensitive enough to see individual rain drops, you should easily be able to see the low-RCS (also called Stealth) aircraft. They are not invisible, just *less* visible than traditional aircraft. Notice the details in the article, though: these measurements were made at a range of 2 km from the radar, over a volume the size of a small bus. Setting aside the very short range, to search the entire sky with a resolution that high would take a very long time.
• #### Re: (Score:2)

People are well known for being very slow at searching filtering large data sets for an individual piece of information, computers on the other hand are very well known for the exact opposite. Of course this kind of radar could be used to create a continuous national 3 dimensional image of airspace and based upon economies of scale useful for, air traffic control, weather forecasting and alien aircraft detection. So not one radar, but many working together.

• #### Re: (Score:2)

I'm not referring to searching through the data to make a detection, yes computers are awesome at that. Just making the measurements over an appreciable fraction of the sky with such accuracy would take a long time. It has its applications, for example when observing the space shuttle (you only need to search a small volume around the shuttle) or when tracking ballistic missles for interception (which is the original purpose for this radar system). So to obtain useful update rates (say, once every minute) a
• #### Re: (Score:2)

" you can jam or shut down "
that's not how stealth works.
You might want to read up.

• #### Re: (Score:2)

You know what has a larger cross-section than a stealth aircraft?

HARM
• #### Detecting stealth != attacking stealth (Score:2)

Stealth aircraft have always been detectable on radar, the only question is "how much radar power" and "how close", and that still applies to indirect radar measurements as well. It's still harder to detect changes in moisture vs a B-52-sized hunk of aluminum glinting back at 100 km.

The real point of stealth is that mission planners know what range the stealth aircraft is detectable at, and the range that said aircraft detects its targets, and the range of its weapons. If it lines up, stealth craft launch

• #### An obvious BOFH bonus (Score:5, Funny)

on Friday June 29, 2012 @03:09AM (#40491029)

"Boss, I'll need some special equipment to see our data in the cloud ..."

• #### Re: (Score:2)

Just in time for tax!
• #### Re: (Score:2)

I appreciate the humor, but on a practical basis, the data analysis must be very similar to that being done at CERN - assuming they are doing serious data analysis. Trillions (ok, here goes, And Trillions) of drop trajectories, etc.

• #### How many raindrops are there in a storm? (Score:5, Funny)

on Friday June 29, 2012 @03:19AM (#40491073)
How many raindrops are there in a storm?
• #### Re: (Score:2)

And, more importantly, if you remove one drop, is it still a storm?

• #### Re: (Score:2)

And, more importantly, if you remove one drop, is it still a storm?

Only if it falls in the woods

• #### Space technology again (Score:2)

So, another solid example of the "Pure science and engineering" stuff that NASA does bleeding into real world applications.

Kind of.

• #### Re: (Score:1)

Even with the best data in the world, weather reporters would fubar 50% of all forecasts. Individual raindrop tracking seems pointless for predicting weather anyways...
• #### Re: (Score:3)

I wish I could remember the author of a journal article I read a few years ago, but in it a mathematician suggested that the models used by weather forecasters were the problem. Some term or terms that were approximated or left out had bigger impacts then scientists thought. He was able to spot this because error in weather forecasts accumulated as the square root of time over the first few days, rather than the chaos-predicted exponential of time.
• #### Re: (Score:2)

a) errors in weather forecasting in short times arise, significantly, from the limited data available as inputs ("data assimilation") and the quality thereof, and this sounds like this could easily give

b) the chaos-predicted exponential with time applies to 1) infinitesimal perturbations, and in 2) very long time average over a stationary attractor. In reality the local/finite-time Lyapunov exponents can vary very widely (usually high when there is interesting weather/convection).

• #### Re: (Score:2)

Yep, that's what the article was about. Chaos theory predicts that the models _should_ give exponential curves right from the start, but in reality, for the first few days, errors built as the _square root_ of time, then went exponential. The author tested the effect of adding deliberate model errors (on top of the unidentified errors already present) and the square root effect got stronger and lasted longer.
The author was saying that weather forcasting was notoriously inaccurate not (only) due to the ch
• #### Re: (Score:2)

Tracking individual rain drops may not help with storm tracking, but would be an excellent way to track cloud rotation it could give much better warnings.
• #### Re: (Score:2)

15 years ago my ex-girlfriend used to work on an atmospheric research radar design as a part of her thesis which was capable of seeing individual raindrops. Not sure what's the big deal here.

• #### ...Under what circumstances? (Score:3, Interesting)

on Friday June 29, 2012 @03:26AM (#40491107) Homepage Journal

The Space Shuttle generally flew only under clear conditions (Challenger excepted, of course); I can't ever recall seeing a photo of the Shuttle taking off or landing in the rain.

Light rain, I can see this working, but a proper Texas Downpour (a.k.a. "cow pissing on a flat rock") is probably going to block the signal after 300m of heavy rain, even at higher energies. I'd be curious to hear what kind of rainstorms and what region of the country they were testing this in. Light mist in Seattle is very different from a tropical thunderstorm in Miami is very different from a squall line in Dallas.

• #### Re:...Under what circumstances? (Score:5, Funny)

on Friday June 29, 2012 @03:30AM (#40491119) Homepage Journal

Might as well karma whore this myself, because someone else is going to, here's a brilliant quote from HHGTTG:

Rob McKenna had two hundred and thirty-one different types of rain entered in his little book, and he didn't like any of them.

Since he had left Denmark the previous afternoon, he had been through types 33 (light pricking drizzle which made the roads slippery), 39 (heavy spotting), 47 to 51 (vertical light drizzle through to sharply slanting light to moderate drizzle freshening), 87 and 88 (two finely distinguished varieties of vertical torrential downpour), 100 (postdownpour squalling, cold), all the sea-storm types between 192 and 213 at once, 123, 124, 126, 127 (mild and intermediate cold gusting, regular and syncopated cab-drumming), 11 (breezy droplets), and now his least favorite of all, 17.

Rain type 17 was a dirty blatter battering against his windshield so hard that it didn't make much odds whether he had his wipers on or off.

And as he drove on, the rain clouds dragged down the sky after him for, though he did not know it, Rob McKenna was a Rain God. All he knew was that his working days were miserable and he had a succession of lousy holidays. All the clouds knew was that they loved him and wanted to be near him, to cherish him and to water him.

• #### Re: (Score:3)

Light rain, I can see this working, but a proper Texas Downpour (a.k.a. "cow pissing on a flat rock") is probably going to block the signal after 300m of heavy rain, even at higher energies.

Depends how high those higher energies: around 20 kt might improve the visibility for 1-2 km.

• #### Re:...Under what circumstances? (Score:5, Informative)

on Friday June 29, 2012 @05:28AM (#40491531) Homepage Journal

Anyways, my point is, you start beaming enough energy through the atmosphere and you can have some unwanted effects. I'm sure the aluminum frame of a Cessna 172 acts as enough of a Faraday Cage against these sorts of things, but with your balls literally on the line, do you really want to test out that theory? ;)

• #### Re: (Score:3)

Yeap. Got a friend in the Navy who works on radar kit. He took himself down the sperm bank and had a batch frozen. I'd not like to work in a job that can kill your balls; but he didn't seem to be that bothered.
• #### Re: (Score:2)

If it was me, I would have modified an athletic cup to block that radiation.

• #### Re: (Score:2)

... with your balls literally on the line, do you really want to test out that theory? ;)

I've had a vasectomy, so I don't particularly care about "sterility" as a side effect.

• #### Re: (Score:3)

That's a nice story that flies in the face of experimental evidence.

Sorry, doesn't happen.

Why don't you tell us the one about using radar to cook a turkey?

• #### Re: (Score:2)

He has several patents to his name in the field of radar technology and still works in retirement with Raytheon as a consultant. I have no reason to question his experiences on the matter.

• #### So much for stealth (Score:5, Interesting)

on Friday June 29, 2012 @03:28AM (#40491113)

If you can detect indvidual raindrops, I suspect detecting a marble sized radar target flying near or over the speed of sound is no problem whatsoever. While this radar is probably too big to put in a fighter a datalink from a ground based version to the fighter will solve that problem quite nicely.

• #### Re: (Score:2)

While this radar is probably too big to put in a fighter

But not a Navy ship. Which is also likely to have directed energy weapons in the near future too.

Since an enemy sailor on deck has a larger RADAR profile than a raindrop, being one within visible range of one of these US Navy ships will be very bad for your health. With just a little bit of automation, a 'killall' command takes on new meaning.

• #### Re: (Score:2)

While this radar is probably too big to put in a fighter

You can say that again. I don't know if you have seen a tico [wikipedia.org] but the old version of this could never get up in the air, much less on a fighter. (there are a total of four of those huge octagonal panels.)

• #### Military Obsolescence. (Score:3, Insightful)

on Friday June 29, 2012 @03:40AM (#40491159)

>Doppler radar can actually spot individual raindrops in a cloudburst,

A raindrop, you say? Like what, a big one? Ok, that's 5mm across for the largest type. From here: http://hypertextbook.com/facts/2001/IgorVolynets.shtml [hypertextbook.com]

It's only a matter of time that other countries develop "weather radar" as pinpoint as this.

The F22 and F35 radar cross sections have been compared to a metal marble and a metal golf ball, respectively. Their "stealth technology" has just been rendered obsolete.

--
BMO

• #### Their Stealth technology has been obsolete since b (Score:4, Informative)

on Friday June 29, 2012 @04:07AM (#40491271) Homepage

Their Stealth technology has been obsolete since before they came out, as long as you can use a heavy-ass ground (or ship) based radar system. Russian S400 "Triumf" deals with stealth just fine, and so does S300 with minor mods. And by "deals" I mean shoots down stealth aircraft from beyond its missile range. That's why we haven't attacked Iran yet. That's not the point of stealth. The point of stealth is that _other planes_ can't see you, and you can take them out from way beyond _their_ radar range.

• #### Re: (Score:3)

Yes your post is consistent with the fact that the first stealth aircraft was - a bomber.
• #### Re: (Score:2)

Nope. The Fokker E.III was a fighter.

• #### Re: (Score:3)

*: The name of the fighter's mothership shall be left as an exercise for the reader.

• #### Re:Their Stealth technology has been obsolete sinc (Score:5, Informative)

<william.chuang' at' `gmail.com'> on Friday June 29, 2012 @11:18AM (#40494351) Homepage

In any war, drones and cruise missiles will be the vanguard of the strike force. The UAVs will fly in to draw fire and jam radars, and cruise missiles will be used to hit anti-aircraft batteries that fire. Sure, in theory the radars can detect stealth aircraft but what about a real electronic warfare environment where we have jammers, target drones, and cruise missiles lighting up any radar site that turns on? The B-2 has its own electronic warfare suite, and as seen above, it can see radar sites much earlier than the radar sites can see them. And don't make any mistake: the radar sites are well within the reach of many of our aircraft. The S400 has a maximum engagement range of 400 kilometers. That is well within the range of the JSOW-ER with a small jet engine that can hit targets from 300 nm. The JASSM-ER has a range of 575 miles, which can be deployed by the B-2.
The B-2 carries the Joint Standoff Weapon (JSOW), which can hit targets from 60 nautical miles. There's a Small Diameter Bomb that can float 60 nmi. Any guy who turns on his radar will have a bad day, guaranteed.

• #### Re: (Score:2)

Except of course neither Raptor nor JSF can carry JSOW-ER, and it can itself be easily shot down by any SAM produced since early 80's, since it's not stealth. The planes that can carry it can be shredded into confetti by S400 from 400km away. And that's the officially advertised range, real range is likely to be greater than that. In addition, S400 has 360 degree radar detection with a range of 600km. So whoever turns on the radar trying to target it is going to have a really bad day, guaranteed.

• #### Re: (Score:2)

You're missing the point when you conclude that "whoever turns on the radar trying to target it is going to have a really bad day, guaranteed." The first part is not true. Killer birds do not have to turn on its radar to find where your radar sites are. It is the S400 has to turn on its radar to detect targets. Killer birds can sit around passively sucking up radiation to hone in on radar sites. Due to the physics of it all, the killer bird gets to detect the enemy radar passively from a much great range th

• #### Re: (Score:2)

Aside from Iraq (which didn't really have much in the way of weaponry), the US has never won a war in which it was a dominant player. Nuff said. All the bells and whistles, and yet the cave dwelling towelheads in Afghanistan are handing our asses to us. What makes you believe that Russians (or Iranians, with Russian weapons) won't be successful at it, in case a conflict breaks out? Why is the US scared shitless of invading Iran and North Korea, or, for that matter any country which has any decent weapons at

• #### ANALYSIS (Score:2)

Someone wrote: "how many raindrops are there in a cloud?" I ask, "how many terrabytes are there in a cloud?. And will you be able to find the golf-ball in that cloud? Or does the USS Whatchemagot have BigBlue under the deck?
• #### raindrops are not designed to misdirect observatio (Score:3)

Stealth technologies are designed to change how an object that can be detected by RADAR is seen by it. Through various material changes, positioning of openings, angles, and the like, you can change how you appear on a RADAR and to a point minimize detection range. You do not have to penetrate foreign airspace much to get a bomb on target and drones don't incur the political risk of dead pilots.

Oh I do not doubt that current stealth technology can be rendered obsolete if not already in some cases, however w

• #### Re: (Score:2)

>Explaining what stealth is

Dude... don't do that. We know what it is. And for those who don't, google is --->over there.

>Oh I do not doubt that current stealth technology can be rendered obsolete if not already in some cases, however while we read about breakthroughs in RADAR technology when it occurs we rarely read about stealth technologies until they are implemented or already surpassed.

I was talking about the planes we have built. If you can detect a .5mm raindrop, at 2km, you sure as hell

• #### Re: (Score:2)

this radar would have the sensitivity to track a 42mm ball bearing 10km, even though the sizes or significantly different every time your radius doubles the rx power decreases by 1/16 a 1mm diameter raindrop would have -80dB rcs or .0001w a 42mm sphere has an rcs of -25dB or 0.05623w it's about 10km that it could be tracked at bases on those values. At 10km any plane can deploy it's weapons and turn around before it gets any closer leaving the radar to track the missile that will hit it.
• #### Re: (Score:3)

Obsolete... for the USA... yes. I bet most of the guys we sell radars to don't get the new-fangled current-generation radars. They probably get the crappy old ones that still can't see our stealth planes.

And once we do start selling them, I bet we could harass our enemies by shooting golf balls with stealth fighter profile into their air space. That'd be hysterical. Just sit a ship out in international water and use an air cannon or something to fire a constant stream of "stealth fighters" into their airs

• #### Re: (Score:2)

I do have to admit, that I would really like to see the golfball gattling in action
• #### Re: (Score:2)

I bet the Mythbusters would be happy to whip one up on the thinnest excuse of a myth. Just sayin'...
• #### Re: (Score:2)

Oh god, I love that idea. ... and then, in the middle of it, you send the actual attack craft. "Guess which one's real, assholes!"

• #### Re: (Score:2)

Oh god, I love that idea. ... and then, in the middle of it, you send the actual attack craft. "Guess which one's real, assholes!"

Probably the one not following a parabolic arc. If the golf ball "chaff" is going fast enough that the arc is undetectable, you don't need the fighters anyway.

• #### Cause that's the problem (Score:3)

on Friday June 29, 2012 @03:43AM (#40491171)

Seeing individual raindrops, that's the problem with current weather radar technology.

Or could it be that it's already so expensive that they cannot blanket the country like
they need to and there are huge gaps in coverage which makes models less accurate?

-AI

• #### Re: (Score:3)

"And now to Chet Stevens for the weather. Using the State's most accurate Doppler Channel 7 Radar." "Thaaanks Judy, moving to the corner of 5th and High st. we notice that 7,276,544 raindrops have fallen at that intersection in the last 2 minutes. However the recent 5 seconds have only seen 125,465 raindrops indicating that the volume of rain is trending downwards, so if you're waiting at that corner to turn left onto High St. you might just wanna wait a few more seconds before turning for your own safety.
• #### Stealth technology.. (Score:1)

So, now that the current generation of stealth coatings on airplanes is obsolete, how long before the US starts to both A) Sell current-gen stealth to other countries, and B) develop next-gen stealth capability.

Remember, stealth doesn't mean a plane is invisible, it just means that the cross section of the plane is just too small to image using normal radar.
• #### Wavelength and TX power? (Score:2)

I wonder about those two almost insignificant characteristics and related health azards.
Any idea?

• #### Re: (Score:2)

Think putting your balls in a microwave.

• #### Re: (Score:2)

Is that because its an accurate analogy, or because you find it personally amusing?
• #### If you can see the raindrops (Score:2)

Then you can see a stealth aircraft displacing those raindrops.
• #### Re: (Score:2)

Stealth aircraft have a large radar signature than raindrops. Most are atleast golf ball sized. If the radar can process so much information (which I doubt), then yeah they can detect stealth aircraft.

• #### So? (Score:2)

I can do that too. What's the big deal?

• #### Great (Score:1)

Now I can't even take a piss in the woods without the government keeping track of the stream?

• #### Re: (Score:2)

Now I can't even take a piss in the woods without the government keeping track of the stream?

Now I can't even take a piss in the woods without the government taxing the stream?

• #### Re: (Score:3)

I've heard about politicians pissing away money on public projects, but this is really a watershed moment.

• #### To see is one thing, to memorize another... (Score:2)

And to manipulate such quantities of data - yet another thing.

And that another another thing is something to think about here. To calculate from raindrop up, or to take chaos theory shortcuts?

I really don't know much about meteorology and chaos theory, but I am sure people thinking about individual raindrop approach do not know, too!

• #### I have a better idea (Score:1)

Most weather services can't even tell me what the temperature is right now or was yesterday. Maybe they should focus on reliably telling what the temperature will be and what the precipitation will be like before they start calculating individual raindrop trajectories.

Oh and by the way, this is impossible and they're lying. If there's a raindrop 500 feet into a pillar of rainfall, chances are it will be blocked so the radar waves would bounce off a raindrop closer to the edge first before even hitting a
• #### A step towards Total Perspective Vortex (Score:2)

Increase the resolution and apply to fairy cake and we're good to go!

there will eventually exist lawsuits where somebody did not receive their "tornado is hitting your house in 5 minutes" warning phone call/text message.
• #### RTFA: the /. header is non-sensical (Score:5, Insightful)

on Friday June 29, 2012 @10:50AM (#40493987) Journal
Unless you have a radar wavelength smaller than the size of a raindrop (\lambda 0.5 mm seems far-fetched), then you CANNOT SPOT INDIVIDUAL RAINDROPS. Furthermore, to achieve the kind of ANGULAR RESOLUTION required, would necessitate a HUGE-sized dish given that roughly speaking the diffracion limit is \Delta \theta ~ \frac{\lambda}{D}, where D = diameter of the dish. What the article says is that you can understand the size and distribution of MANY small raindrops in a cloud, which presumably before you could not. I am amazed how little basic physics /.-tters seem to know.
• #### Waste (Score:2)

This is good news. Now we can finally settle the question of whether commercial passenger aircraft do, in fact, jettison the contents of their waste tanks in flight.
• #### Back to the drawing board (Score:2)

Well, I guess that plan to infiltrate earth in tiny spaceships disguised as water drops is out the window now.

Thanks to the US Navy!

• #### Skynet (Score:3)

on Friday June 29, 2012 @08:42PM (#40501051)
STOP GIVING SKYNET NEW TOYS!

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