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I'm not really fond of PIPS2 - it's an ancient, overly conservative model which overestimates Arctic ice thickness, thus greatly impressing WUWT readers, for example, because of its "US Navy" pedigree:

As of July 1996, a coupled ice-ocean model, the Polar Ice Prediction System (PIPS 2.0), was implemented operationally by FNMOC as a replacement for the three original forecast systems. PIPS 2.0 forecasts conditions in all sea ice covered areas in the northern hemisphere (down to 30°N in latitude). The horizontal grid resolution of the model is 0.28 degrees and uses 15 vertical levels. PIPS 2.0 produces forecast fields of ice displacement, ice thickness, ice concentration (ice edge) and the growth/decay of ice based on both dynamic and thermodynamic effects. PIPS 2.0 is driven by atmospheric forcing from the Navy Operational Global Atmospheric System (NOGAPS) (Hogan et al., 1991)

The fact that this little model runs on a PC somewhere in a Naval office doesn't mean that it's still used by serious Navy people. The Fleet Numerical Meteorology and Oceanography Center (or FNMOC), which originally worked on PIPS starting in the 1980's, doesn't even mention it anymore - try searching for it:

The Naval Meteorology and Oceanography Command which runs this website is located at the very Stennis Space Center where PIPS 2.0 is running in some office - but the official, public website gives no links to this outdated model. It does however helpfully direct you to the National Ice Center, a collaborator:

I like the KML files for Google Earth found there, among other things:
We've come a long way since 1996.

I'll gladly sign petitions for making Cryosat-2 data nicely available to the public, though.

L. Hamilton

Feedback on feedback: I answered the PIPS survey, and got a nice email in response that seems worth sharing:

"Dr. Hamilton,

We appreciate your kind words concerning PIPS and are glad that you find it to be a useful research tool.

Currently our latest coupled ice/ocean model, the Arctic Cap Nowcast/Forecast System (ACNFS) is undergoing its final operational testing and should be available online hopefully by the end of the year. The resolution of this model is 3.5 km (as opposed to the 27 km of PIPS).

Thank you for the suggestion concerning the improved detailed non-technical description of the model. We will incorporate your comments into the new ACNFS website."

Artful Dodger

I've always thought of PIPS from the point of view of the only U.S. Navy customers which could use the operational data. That is, Fleet Ballistic Nuclear submarines.

These users would primarily be interested in the maximum Ice Cover they might encounter when operating in a particular area, which means what are the largest 'chunky bits'. To fulfill their mission, SSBNs need to be able to surface at any time, which means they need to know the maximum possible sea ice thickness overhead.

Because SSBN's operate with inertial navigation (since GPS is unavailable underwater), their gyros drift over the extended periods these subs remain submerged. Thus an Area forecast is appropriate, and especially important for Hudson Bay, a main winter cruise location.

Thus, I consider PIPS 2.0 Ice Thickness Forecast's to be like Aviation Sectional Charts, which show the minimum safe altitude for operations in any particular Area.

Thus the PIPS 2.0 sea ice thickness chart is a plot of maximums, not of the average thickness.

Kevin McKinney

". . . especially important for Hudson Bay, a main winter cruise location [for US ballistic missile subs.]"

It's highly tangential to the main point, but Lodger, are you sure about that? I'd have thought that operating nuclear armed subs *way* into Canadian territorial waters would not have been a likely US choice; too much needless political heat--and besides, the archipelago and Arctic basin are much closer to Russia. . .

Artful Dodger

Hi Keven, agreed OT, except in that it potentially affects all life on Earth ;^)

The U.S. considers Hudson Bay (and the NW Passage) to be International Waters. Russia is not a target, and recently ratified Arms Control Treaties reinforce that. You would not want to overfly the territory of a nervous neighbor... Have a look with Google Earth's Distance tool to see some Great Circle paths.

Ohio-class SSBNs carry the Trident II SLBM. These travel in sub-orbital trajectories at an undisclosed speed, greater than 21,000 km/h. It would take a Trident II warhead, fired from the exact opposite side of the world less than 20 minutes to hit its target. Standard expected flight times are 13 minutes, with close-in SSBNs about 8 minutes from launch to target.

Canada has a plan to install an undersea sensor network in the NW Passage, I think to be operational by 2016? It was covered by the CBC. No word on plans for Hudson Bay.


If nuclear subs can't get GPS, how would they get new 24 hour forecasts from PIPS2 every day ? PIPS needs daily atmospheric forcing data from satellite feeds.

Also, the end result of a PIPS 2.0 "forecast" is a tiny image 354 pixels by 398 pixels - this includes the title and the entire Northern Hemisphere down to 40° latitude:

Do you seriously think Fleet Ballistic Nuclear submarines are going to use a tiny 30 day-old image like this to find which pixel they are beneath, and then match the color of the pixel to:

rather than trust their own upward looking sonar ?

I doubt anybody uses PIPS 2.0 results "operationally". Or do people think the public website is just a dumbed-down version of PIPS 2.0, and submarines get the full 27km hi-res maps with interface software for easily matching estimated position to overhead ice thickness, and the submarines can shoot ice-penetrating, recoverable antenna's (classified, so they are never mentioned) through the overhead ice to get that crucial 24-hour update every day ?

@L. Hamilton
The Arctic Cap Nowcast/Forecast System (ACNFS)sounds interesting - perhaps this is what they renamed PIPS 3.0 to (which Maslowski used to work on...)

Artful Dodger

Anu, lol u need to ask a squid. But u know active sonar is inconsistent with stealth, and has no value for patrol planning. Which element of the surface fleet do u thick uses the thickness forecast product? :^)


Hmnn - Some interesting comments on info, resources, & paywalls. LOL.

Shucks, if PIPS graphics - images disappear behind a paywall because they're only useful to 'squids' with an authorized account, then we're going to start missing a lot of posts on Ice Displacements projection - predictions.

Add a theme to the topic. IMHO
there is a concerted effort by some parties, especially in the USA, to silence global warming advocates and one way of doing it is by denying them information (yes and discrediting usefulness of spending public funds to freely disseminate data).

I still say participate in the surveys and tell them something. My obsession with following Arctic Ice Data could be in jeopardy.

You folks don't want me have withdrawal symptoms do you?

Peter Ellis

I'll be amazed if the submarines use sea ice thickness models at all - what would they use it for?

You have 1.5km of ocean depth to play with, why do they care whether the ice above them is 1m or 10m thick? If they're surfacing, they're almost certainly looking for leads, not even thin ice, and they're looking for something at most a couple of hundred metres across. Again, what use is an ocean-wide thickness model: any thickness model?

The Navy is quite explicit what they use it for: forecasting of location of the ice edge. That's for surface ships and icebreakers, not submarines, and whatever's going on in the middle of the pack is irrelevant to them.


@ Peter Ellis | March 29, 2011 at 12:33

Peter, in your opinion the many posts we see in various places about Ice Displacement provided by PIPS, are they just entertaining, or insightful, or useful, or a waste of time and space?

Peter Ellis

Haven't a scooby! We're all amateurs here, unless we have some published, peer-reviewed Arctic scientists lurking that I don't know about, so I guess we get to define what we find entertaining, insightful or useful.

Don't mistake me for any kind of expert: I'm a scientist, but the wrong sort of scientist. The most I'll lay claim to is a good understanding of physical scale (a few metres of ice compared to a vast depth of ocean), and a reasonable understanding of physical processes - see the recent tsunami discussion for example.

The submarine stuff is purely based on what seems common sense to me. Well, that plus an understanding of the size of a submarine in context (about 1/200 of a pixel in length).


Hi all,

completely off-topic again, but Prince Harry is off to the Arctic.

There are 2 really good stories about this up at the Guardian website.

I've got to go to work...


@Lodger, I don't know if arctic submarines looking to surface really need to be stealthy; and if they are not going to surface, they don't really care (operationally) how thick the ice is overhead.

In fact, for many decades, they've been blaring sonar all over the Arctic, which was much appreciated years later by the scientists studying ice thinning:

My point is, I don't think anybody in the Navy uses the PIPS thickness data - why would they ? PIPS was popularized by WUWT because it's available on the Web, and its 1996-era model showed Arctic ice remaining thick, while PIOMAS, TOPAZ and most measurements (submarine, ICESat, airplanes, etc.) showed the ice thinning dramatically over decades. The WUWT "argument" has always been the US Navy "thickness data" (the PIPS2 model running on a PC) must be the better than everybody else who show the Arctic ice is thinning, because they use that data to "save lives".

@Peter Ellis - I agree. The idea of a US Navy submarine pulling up a PIPS ice thickness map in the navigation room while under the Arctic ice is laughable.
But I think a nuclear submarine is even smaller than your 1/200 of a pixel estimate:
Wrangel Island = 145 km (90 miles) long
On PIPS image, this is 3 pixels long
Los Angeles class submarine = 362 feet long (110 m)
48.333 km/pixel, submarine 0.11 km long --> 439 submarine lengths in a pixel
For the larger Ohio class submarine (170 m long), it would be 1/284 of a pixel in length
(Seawolf and Virginia class subs are intermediate lengths)

Peter Ellis

Considering I measured the gif off the screen by scribbling on a Post-It, I think that's an acceptable error margin :-p

The point is your sub would need to be at least two orders of magnitude larger for that resolution of map to be useful.

Another way of looking at it is that a submarine would have to travel for 2-3 hours at full speed to get from one pixel to the neighbouring one. Is that a useful margin of error for your decision on where to surface? What if the nearest patch of thin ice was (gasp) three pixels away? Spend half a day getting there? A nuclear war would be over by then.

Kevin McKinney

Lodger, still gnawing over territoriality of Hudson Bay. Near as I can find, the US accepts the NWP as 'territorial waters' of Canada but not 'internal waters.' That means right of innocent passage. But Hudson Bay seems not to have been in dispute between the two nations since the early 20th century (you can Google up a 1903 NYT story on this!)

The best source I found is here:


(See statement from Capt. Roach, USN (ret.))

He talks about US subs using the NWP, especially in winter, but clearly that would be the deep water route and would likely not involve Hudson Bay at all.

Cf. also the 2005 controversy about US subs in the Archipelago.

But maybe you know something I don't? You really didn't say much directly in that last comment. . .

Artful Dodger

Hi Keven,

Everything I know about Submarines comes from Tom Clancy, Larry Bond, and Jared (Turkey Sub, 6-inch :^)

The Soviets announced (and the NY Times reported on Aug 28, 1959) that they could drive a Submarine into Hudson Bay under the Arctic Sea Ice, and launch missiles on CONUS.

The 'Silent Service' would never announce that a US Attack Sub shadowed a Soviet Sub all the way from the Sub pens in Severomorsk to Hudson Bay.

In a stunning coincidence, the Govt of Canadian established NAVFAC, an early form of SOSUS, in Hudson Bay and terminating in Argentia, NFLD in 1959.

You won't find any unclassified info newer than 50 years, and Boomers hadn't yet been created by 1961. But when USS Maine (SSBN-741) sailed from Groton, CT in July 1995 she was the first Electric Boat who's radiated acoustic signature was below ambient: a true Black Hole. She closes her hatches and disappears for 6 months. Not even LA class attack subs can find her... "We Hide with Pride".

To state the obvious, some advantages to Winter Patrols in Hudson Bay are a single point of ingress for any OPFOR, impunity from AC-dropped sonobuoys, or Surface Combatants with Heliborne Dipping Sonars. It's like a dark abandoned alley, where one guy is shining a flashlight, and the other guy is hiding in the shadows with a pistol... who'd you rather be?

If you really want to learn to dive with the Dolphins, get yourself a copy of Harpoon. The TO&E database is impressive, as are the scenarios.

By the way, there also were no nuclear-armed Bomarcs in Canada in 1958, either (the ramp area was temporarily ceded to the US). And the last time I was aboard a US Sub was Dec 2009, but that was way out at Pearl...

Artful Dodger

Anu, you may be confusing operational objectives of Attack boats with Boomers. The first bit of noise emitted by a properly driven SSBN is a slug of HP air, just before it's Trident D2 breaches the surface...

Artful Dodger

Peter, good thought process. SSBNs need to be able to launch within just minutes to fulfill their mission. That's why they're called "Deterrence Patrols".

In terms of the 3D operating environment in the Arctic, first ask yourself what the crush depth is for a steel hulled boat. You'll find they can go to maybe 800 m before things start really complaining, and normally much less.

A more important operational figure is the depth of the Halocline, which separates shallow fresher water from deeper saltier water. It forms an acoustic shield over top of an already stealthy boat, which is a powerful position indeed.

Especially with 20 years of fuel, air and water onboard...

Artful Dodger

Oh, and Anu, the Sub Captain doesn't plan his Patrol route. That's done by the Commodore at SUBLANTFLEET. He's the guy with the planning maps, and an open line to National Command Authority. COMMS is by ELF for breaking news.

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