By Steven Goddard
There have been a number of inaccurate claims made by commentors about Navy PIPS2 ice thickness maps. These claims have been along the lines of :
- PIPS isn’t used by the Navy any more, because it isn’t accurate enough
- PIPS maps over-represent ice because they don’t see areas of open water
- PIPS maps don’t take into account ice concentration. They consider the ice to be 100% concentrated
- PIPS is just a model. It isn’t an accurate representation of the ice.
The US Navy clearly refutes these claims –
04/06/2010 – Pamela Posey
The Polar Ice Prediction System (PIPS 2.0) is the current U.S. Navy’s operational ice forecasting system.
PIPS 2.0 forecasts ice conditions in the northern hemisphere with a horizontal grid resolution ranging from 17-33 km depending on the grid location. The system couples the Hibler ice model to the Cox ocean model and exchanges information by interfacing the top level of the ocean model with the ice model. Ice concentration fields derived from the Special Sensor Microwave/Imager (SSM/I) are assimilated into the PIPS 2.0 system along the ice edge. The system produces a 120-hour forecast of ice fields which are sent to the National Ice Center (NIC) to be used in their daily ice forecasts.
The Navy also refutes the claims that they don’t correct for concentration :
The model-derived ice thickness field and the ocean surface temperature field are then adjusted to be consistent with the concentration data.
These models are required to go through rigorous validation studies to prove their capability to produce accurate short term variability. Data assimilation plays a major role in the accuracy of these forecasts. Once operational, continuous quality control and evaluation of the products may be used to upgrade the system and improve forecast accuracy.
The video below for June 10, 2010 shows that PIPS maps accurately reproduce current ice conditions. It overlays the UIUC ice concentration map on the PIPS map.
Map sources :
http://arctic.atmos.uiuc.edu/cryosphere/NEWIMAGES/arctic.seaice.color.000.png
http://www7320.nrlssc.navy.mil/pips2/archive/pips2_thick/2010/pips2_thick.2010061100.gif
As you can see, areas of open water are shown as open water, and areas of low concentration also have lower thicknesses. The incorrect claims repeated over and over and over again by FUDsters just don’t hold any water.
PIPS2 is not perfect. Here is what the Navy says :
A recent study by a group of scientists from the NIC and NOAA (Van Woert et al., 2001), showed that although the PIPS 2.0 forecasts (48-hour) were better than persistence on average, there were still substantial biases in its prediction of the growth and decay of sea ice in the marginal ice zone. PIPS 2.0 often over-pre- dicts the amount of ice in the Barents Sea and therefore often places the ice edge too far south. In contrast, PIPS 2.0 often under-predicts the ice extent in the Labrador Sea and Hudson Bay.
This doesn’t affect my calculations, because I am only measuring regions which normally contain significant amounts of late summer ice. Also, my comparisons are relative year over year comparisons. The absolute values of ice thickness are not important to my conclusions.
Conclusion : PIPS2 maps is the best available and are used by the US Navy. They are quite accurate and they do account for ice concentration. No doubt, some commentors will continue to ignore the facts, and post instead what suits their agenda.
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From: jeff brown on June 13, 2010 at 11:12 pm
You should learn how to get the original links, rather that copy-and-paste the Google search links.
Short form: http://www.star.nesdis.noaa.gov/star/documents/seminardocs/ClementeColon_2007-02-20.pdf
2007 presentation, long winded, with a relatively brief mention of how great and better the future PIPS 3.0 will be. Heard the same before. Slide 35 proclaims the operational transition and validation is underway, at least the validation part was likely true. Slide 37 shows three maps from September 2003, 2.0 without SSMI assimilation, 3.0 without SSMI assimilation, and the SSMI observations. From this it is concluded that 3.0 without SSMI assimilation more closely matches SSMI.
Thus this is a false comparison when used to show any deficiencies with 2.0, as according to the PIPS 2.0 site they are using SSMI data.
Paper published in 2004 I already mentioned before.
Short form: http://www.clivar.org/organization/wgomd/wgomd5/gfdl04/Chassignet.ppt
Another old powerpoint presentation. File Properties (contained within ppt file) says it’s from 2004. Slide 5 on future systems lists PIPS 3.0 as CICE coupled to NCOM, 4.0 having CICE coupled to HYCOM. Per a previously mentioned 2005 presentation PIPS 3.0 was to have come in two versions, the first being CICE coupled to NCOM (3.0 G-NCOM), the second CICE coupled to HYCOM (3.0 G-HYCOM). All you’re showing there is a name change.
I think it is clear it is dated, but the Navy has had one heck of a time trying to get anything better finished up and deployed. Thus it is still the best that the Navy has deployed and the best that it uses.
It is also clear certain people would benefit from reading my posts. 🙂
Phil. says:
June 13, 2010 at 3:22 pm
What you wrote certainly did.
you may have overlooked this:
“…..believe that manmade global warming disasters are here now and worse are coming?”
http://wattsupwiththat.com/2010/06/12/what-is-pips/#comment-408784
I came out and asked. I made no ‘implication’.
Tom P says:
June 14, 2010 at 1:18 am
Tom, thanks for doing the comparison, that is very useful and important information.
Good job.
Kadaka, what you don’t seem to give any credit to is the fact that all those authors of publications/presentations regarding accuracy of PIPS2.0 and improved accuracy of PIPS3.0 over PIPS2.0 are those people who actually work at NIC still today, or have worked at NIC in the past. They, not us, know exactly what is going on with the Navy forecasting model. The fact that they show in their papers and presentations that there is a better model that PIPS2.0 out there, makes me believe they too are using a better model.
Jeff,
What you are not giving any credit to is the fact that PIPS 2.0 is in production and its data is publicly available. No one is arguing that 2.0 is better or as good as 3.0, but PIPS 3.0 is still being validated so the only one available is 2.0. Get it?
jeff brown says:
June 14, 2010 at 8:32 am
Kadaka, what you don’t seem to give any credit to is the fact that all those authors of publications/presentations regarding accuracy of PIPS2.0 and improved accuracy of PIPS3.0 over PIPS2.0 are those people who actually work at NIC still today, or have worked at NIC in the past. They, not us, know exactly what is going on with the Navy forecasting model. The fact that they show in their papers and presentations that there is a better model that PIPS2.0 out there, makes me believe they too are using a better model.
Judging by what Posey has written it seems fairly obvious that PIPS3.0 is being used for research use but not yet for the daily forecasts.
“Coupled ice-ocean models, such as those used by
PIPS 2.0 and PIPS 3.0, are most often applied in academic
studies of global climate issues such as climate
change. In these studies the models are used for
decadal or longer simulations and focus on long term
changes in the overall pattern of ice thickness and ice
extent. This application of the coupled model requires
access to powerful computers and large quantities of
computer time. However, coupled ice-ocean models
used for forecasting face a different set of requirements.
As forecasts are concerned with sea ice variability
on much shorter time scales, the models must be
designed to produce the most accurate daily changes
in ice concentration, ice edge location and ice motion.
These models are required to go through rigorous
validation studies to prove their capability to produce
accurate short term variability. Data assimilation plays
a major role in the accuracy of these forecasts. Once
operational, continuous quality control and evaluation
of the products may be used to upgrade the system and
improve forecast accuracy. In addition, forecast
systems are limited by the amount of computer
resources available for each forecast as they compete
with other forecast models each day. Therefore the
combined model/assimilation system must be
designed to “fit” within these limitations. This places
restrictions on the “size” or grid resolution of the models
as well as the complexity of the model parameterizations
and the data assimilation techniques. Each of
these issues must be taken into account when developing
a new forecast system.”
Speaking of the North, look at how it’s 84F in Churchill right now, a new record.
http://www.wunderground.com/global/stations/71913.html
Thanks for everyone for the details provided on this interesting topic. I really wish Ms. Posey would have returned my email as it would have cleared up so much of this speculation. After reading everyone’s posts, and looking at so many pdf’s about PIPS/CICE/HYCOM/NCOM/G-NCOM etc. etc. etc. I personally have come to these conclusions:
1) PIPS 3.0 exists and is being used daily by the NAVOCEANO as Ms. Posey said, but it still may be in “validation” mode. operational but “secret” or something in between.
2) PIPS 3.0 is a much higher quality and more accurate sea ice forecasting model than PIPS 2.0
3) The Navy may be also using PIPS 2.0 (but a version that is a higher res and scaled up from what it has released on the public site).
4) The reason for the delay in the offiical release of PIPS 3.0 could be any number and combinations of factors including: the failure of IceSat which was critical in validation, the unplanned delay in release due to accuracy issues, the planned delay in release due to the Bush Presidential directive related to the Arctic and national security (see my previous posts related to this), the delay in getting a down-scaled version of PIPS 3.0 that the public and non-military researchers could use, or any number of other simlar reasons.
5) The Navy would not release it’s best navigational tool of for the Arctic on a public web site…thus, PIPS 2.0 is hardly what the Navy would use for serious daily operations in the Arctic. Thus, whatever they are really using, whether it be PIPS 3.0, or a vastly scaled up version of PIPS 2.0, it is not the data that they give to the publc.
And now, I’m PIP’d out. Next topic please…
@ur momisugly Steve Goddard
Thank for the link to the pips2 color key Steve, some other commenter supplied it also.
Just getting acclimated to NIC’s site, never had tread there. I have a couple of questions you might already know without me wasting tons of time. One thing I’m curious is the Hudson Bay area and tributaries. There is marked differences there to some of the last years, but hey, that is understandable, eastern Canada has a rather warm winter (as they transported the cold to us! :)). How much of this difference in concentration and volume is solely Hudson Bay and tributaries related up to this date, seems sizeable in concentration area anyway, do you already know?. The main body of the arctic doesn’t seem to show that much marked drop visually. Some of this might just be due to the projection distortions magnifying the southern regions.
Also, NIC projections seem to come primarily from satellite-only readings, QUICKSAT, OLS, DMSP, ENVISAT, RADARSAT, AVHRR; are there any systematic on-site physical measurements included at all in these projected maps that you know of? I.e., is this primarily a satellite-driven model that creates these projections at NIC?
May have been answered before in posts/comments, if so, just say look backwards!
And Steve, you might have already seen this but it was new to me…
http://www.goes-r.gov/downloads/GOES%20Users'%20Conference%20V/GUC%20V%20Posters%202/poster_Wang%2059.ppt
(Couldn’t read it without first saving it to disk and then pulling it up in PowerPoint so I could zoom).
What caught my eye is the 1999 submarine ice thickness tests within. This paper has data plots of PIOMAS always being too high in ice thickness readings in 1999. Now, some commenters here swear it is so accurate now, 2010, hmmm…, they must have markedly lowered the thickness that PIOMAS is estimating in the years since 1999. What? That is the exact opposite we see in the temperature fiasco. Now plot a regression in PIOMAS and say the world is melting… melting…, well maybe not, but I did find that curious.
REPLY: Paste the address, the apostophe breaks the wordpress url software
Charles, mods:
The link I just passed to Steve breaks at the ‘(apos) but encoding didn’t seem to help on this end at least. Can you fix it. The ‘(apos) is real and part of the address. Never hit that one before!! 😉
REPLY: Can’t find a way to fix it: paste the address. RT – Mod
R. Gates says:
June 14, 2010 at 12:21 pm
Disagree with Number 1.
Please see the conclusion of this January 2010 report that Pamela Posey is a co-author of:
http://www.dtic.mil/cgibin/GetTRDocAD=ADA513212&Location=U2&doc=GetTRDoc.pdf
A short excerpt:
“Currently, the operational coupled sea ice forecasting system run daily at
NAVOCEANO is the Polar Ice Prediction System (PIPS 2.0) and has a resolution of-27 km.”
Agree with Number 2
3-5 are pure speculation and unverifiable one way or another.
Steve, here’s a workable link (weird)…
http://www.goes-r.gov/downloads/GOES%20Users%27%20Conference%20V/GUC%20V%20Posters%202/poster_Wang%2059.ppt
Re: R. Gates on June 14, 2010 at 12:21 pm
So after contaminating numerous articles with discourses about PIPS 3.0, how much better it is, how it is what the Navy uses, how 2.0 has long been discarded, faced with many pieces of evidence showing how 3.0 never made it out of the development and validation stage (in either version) and 2.0 is still the operational model for sea ice forecasting, with much of that evidence having been previously cited as proof of R. Gates’ contentions yet shown to state something other than as he presented them, the following major shift in R. Gates position has been noted:
‘Alright, PIPS 2.0 may still be running. But they’re sure not using it for anything serious, especially not as presented to the public on the 2.0 site!’
Thus is noted, given this example, the ability of R. Gates to examine evidence and reach logical scientific conclusions free of pre-conceived biases. 😉
First: Tom P, your links are fantastic ! (especially june 12 5:51PM)
Second: Pips 2.0 is still used because the Icebreakers want a DAILY forecast.
More Accurate thickness — but late — means nothing to a ship that sank last week.
3. Note Amino Acid’s Cryosphere links: their sidebar indicates colors correspond to CONCENTRATION – – which is why Cryosphere is so alike to Pips 2.0.
4. Compare May 6 to June 6: wow ! Despite a record April 2.68 degrees above normal & May 2.63 above normal,
Pips has … 5 meter superthick Siberian Ice tripling & more !
The New Ice Age is coming !
>>June: http://www7320.nrlssc.navy.mil/pips2/archive/retrievepic.html?filetype=Thickness&year=2010&month=6&day=6
>>May 6: http://www7320.nrlssc.navy.mil/pips2/archive/retrievepic.html?filetype=Thickness&year=2010&month=5&day=6
(note all you have to do is alter the dates in the web address, e.g. change 2010 to 2009)
5. Zhang’s forecast is NOT PIOMAS’s. It just USES it.
There are 7 researchers that use it as A FRAMEWORK for their DIFFERING Forecasts. Zhang & Rothrock, who invented it, even INVITE US, the Public, TO MAKE SOME PREDICTIONS http://psc.apl.washington.edu/zhang/IDAO/predict.html
What we are arguing about is whether Piomas (and/or Pips) Is Accurate, when MEASURED DATA is plugged in. I.e, not for Forescasts, but in the NOW.
Here Tom P’s chart is right on target : http://img811.imageshack.us/img811/5835/pipsvspiomas.png
… Actually a shock they are so alike, even to the identical underestimate of the 2007 Melt.
For my purposes, all I want is whether I can trust the the 5800 cubic Kilometer figure for the last minimum (Spt 2009) (as I predict based on the severity of the El Nino & 2010/2007 = 1.8/1.1 so 2007’s loss of 4000 according to ICESAT means 6545 loss this year, versus last )
Now 2009 was when Piomas had ICEBRIDGE airplane laser Data that Directly measured thickness so I think I CAN trust it. And Tom’s chart has Pips backing that up !
(as of May 1, 2010: Piomas is back to the lower pre- June 2008 accuracy, when Piomas used concentration as an analog for thickness, just like Pips, except near shore where it had DATA — which probably explains the congruence with Pips for 2005-09, including their Mutual underestimate of 2007’s melt).
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