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Jim Hunt
South West England
Recent Activity
G man - We're obviously wasting our time here. Bill posted the exact same link that you originally posted in an endeavour to point out to you that you're trying to compare apples with oranges once again. It seems you didn't get the message. You also seem convinced that "lake ice" has no bearing on your original question about differences between the DMI and NSIDC extent metrics. Having now done your due diligence, what's your explanation for those differences?
Toggle Commented yesterday on Early record, late record at Arctic Sea Ice
G man - So should I believe some guy on the internet who talks about things that "appear obvious" or someone from DMI who writes academic papers about sea ice concentration algorithms for a living? Aren't you even slightly curious about the apparent difference of opinion at DMI? The climo map you link to says it's "for the Arctic ocean" but nonetheless shows some pretty colours in the Baltic. It's also circular instead of rectangular. Weird, huh?
Toggle Commented 2 days ago on Early record, late record at Arctic Sea Ice
G man - For the umpteenth time, the answer I received said "The Great Lakes are included in both the old and the new version of the OSISAF data". The verbiage accompanying the "new" version of DMI extent says: "The plot above replaces an earlier sea ice extent plot, that was based on data with the coastal zones masked out." If most of the Great Lakes were masked out in the "old version", it doesn't imply they are also mostly masked out in the "new" version. Quite the reverse in fact.
Toggle Commented 3 days ago on Early record, late record at Arctic Sea Ice
G man - Perhaps you could point your contact at DMI at the answer I received from my contact at DMI last year around this time, and ask for further clarification? Whilst you're at it perhaps you might remind them that their web site (the bits I'm looking at at least) explicitly refers to "Total sea ice extent on the northern hemisphere" everywhere except in the title of their "new" graph? http://ocean.dmi.dk/arctic/icecover.uk.php
Toggle Commented 3 days ago on Early record, late record at Arctic Sea Ice
G man - What was the question you asked DMI, what was their precise answer, and who provided it? Have you bothered to read this yet? http://forum.arctic-sea-ice.net/index.php/topic,782.msg22214.html#msg22214 I take it that you are aware that there is more than one DMI "Arctic package"?
Toggle Commented 4 days ago on Early record, late record at Arctic Sea Ice
I could have saved you going to all that trouble G man, since I asked DMI that very question quite some time ago. Please do let me know if you receive a different answer to the one they gave me. In the meantime I feel sure you must have many happy hours ahead of you reading the relevant manual: http://www.osi-saf.org/biblio/docs/ss2_pmseaice_3_11.pdf If you'd like to start crunching the numbers yourself there's even some instructions on how to go about doing so over on the forum: http://forum.arctic-sea-ice.net/index.php/topic,782.0.html Please do not hesitate to ask if there's anything there you do not understand.
Toggle Commented 7 days ago on Early record, late record at Arctic Sea Ice
G man - At the risk of repeating myself, and as you can check for yourself by clicking the links I helpfully provided, whatever your views (or indeed mine) on the matter may be the OSISAF concentration data on which DMI base their numbers include the Great Lakes. The NSIDC concentration data, on the other hand, do not: ftp://sidads.colorado.edu/pub/DATASETS/nsidc0081_nrt_nasateam_seaice/browse/north/nt_20150319_f17_nrt_n.png Hopefully you have learned by now that even at NERSC area != extent? just in case: http://arctic-roos.org/observations/satellite-data/sea-ice/observation_images/ssmi1_ice_ext.png Can you provide any photographic evidence, photoshopped or otherwise, of wolves eating ice seals?
Toggle Commented 7 days ago on Early record, late record at Arctic Sea Ice
G man - You're trying to compare apples with oranges. Your first link is to a graph of area, not extent. Which is why the numbers are lower than those quoted by NSIDC. Your second link is (despite the title!) to a graph of Northern Hemisphere ice extent, including the Great Lakes, which is why the numbers are higher than those quoted by NSIDC, for 2015 at least. Compare e.g. http://osisaf.met.no/p/ice/nh/conc/imgs/OSI_HL_SAF_201503191200_pal.jpg and http://osisaf.met.no/p/ice/nh/conc/imgs/OSI_HL_SAF_201103191200_pal.jpg
Toggle Commented 7 days ago on Early record, late record at Arctic Sea Ice
NASA have a video out too, along with this associated article: http://www.nasa.gov/content/goddard/2015-arctic-sea-ice-maximum-annual-extent-is-lowest-on-record/
Toggle Commented Mar 19, 2015 on Early record, late record at Arctic Sea Ice
"Speaking of stratospheric warming, here's NOAA's 50hpa temp anomaly animation showing one just getting underway in the NH." Over the North Atlantic?! A UK Met Office video on SSWs https://youtu.be/1MiUlTthSNA plus “The Achilles heel of the North Atlantic" http://unews.utah.edu/news_releases/stratosphere-targets-deep-sea-to-shape-climate/
Toggle Commented Mar 19, 2015 on Early record, late record at Arctic Sea Ice
Cryosphere Today area has reported a 50 k drop today, much as predicted! As Bill was hinting, the NSIDC daily extent fell by over 100 k also. Are you willing to call it yet Neven?!
Toggle Commented Mar 18, 2015 on Early record, late record at Arctic Sea Ice
V&N - An extract from the conclusions of Lindsay and Schweiger 2015: There is no gold standard for the estimation of the mean thickness of sea ice. All of the existing measurement techniques have one or more large sources of uncertainty. In situ measurements from the surface cannot sample the full thickness distribution. The submarine ULS measurements depend of the first-return echo to determine the ice draft, which is a potential source of unknown bias that may be a function of the bottom roughness. The mooring ULS measurementsmay also be subject to this same source of error. Both have potential errors in determining the open water level and accounting for the correct snow water equivalent. The satellite and airborne lidar observations depend on reliable detection of the surface height of nearby leads to accurately determine the height of the ocean surface and hence the total freeboard. The Air-EM measurements require an independent estimate of the snow depth, as do the satellite lidar measurements. All of the measurements struggle with obtaining an accurate mean value when the thickness is highly variable within the sensor footprint due to ridging. Finally, none of the measurements have been verified against other observations over regions that encompass the full ice thickness distribution of the area. All of which indicates that measuring sea ice thickness (and hence volume) is a decidedly tricky undertaking. I fear much the same applies to modelling it also.
Toggle Commented Mar 17, 2015 on PIOMAS March 2015 at Arctic Sea Ice
Kevin/Wayne, I currently find myself taking issues of export and the like from the PIOMAS thread on here over to the forum: http://forum.arctic-sea-ice.net/index.php/topic,1149.msg47797.html#msg47797
Toggle Commented Mar 16, 2015 on Mad max? at Arctic Sea Ice
Chris, I wanted to include some videos in my response, so I've endeavoured to continue the conversation over on the forum: http://forum.arctic-sea-ice.net/index.php/topic,1149.msg47797.html#msg47797 There's undoubtedly been some export from the Central Arctic, but what has filled the space left behind? In brief, whether looking at the current state of play from the micro level of a single buoy or the macro level of a basin wide overview I'm still not convinced PIOMAS has a particularly good handle on the "reality" around the margins, even if it is right about continuing volume increases in the centre. And if it's wrong around the margins who's to say it's not wrong in the centre also?
Toggle Commented Mar 16, 2015 on PIOMAS March 2015 at Arctic Sea Ice
Sorry Wayne. Things should now work as advertised!
Toggle Commented Mar 13, 2015 on PIOMAS March 2015 at Arctic Sea Ice
Bill - Christow does indeed possess a pub called The Artichoke Inn. Sadly I have never partaken of a pint there. However I do look forward to meeting you in the vicinity on the 24th!
Toggle Commented Mar 13, 2015 on Thinner and thinner at Arctic Sea Ice
I'm afraid I can't help but wonder about the PIOMAS "average thickness". Ice mass balance buoy 2013F has survived 2 winters in the Beaufort Sea with its temperature sensors intact. Here's what they revealed at the end of the freezing season last year: and here's where we're up to so far this winter. Click the images for larger versions! For an explanation of the graphs see: http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/ Now this is of course a very small sample from a very large Arctic, but the floe 2013F is sat on undoubtedly counts as multi-year ice. However currently it's only slightly thicker than it was at the same time last year. The top and bottom sensors on the buoy say the floe is 1.8 m thick. The temperature sensors, which are located in a slightly different place, suggest it's more like 1.3 m thick. PIOMAS has the thickness of that area of the Beaufort Sea at around 2.2 m.
Toggle Commented Mar 13, 2015 on PIOMAS March 2015 at Arctic Sea Ice
You're a braver man than I Cincinnatus, calling the maximum so early! Ever tasted crow stew?
Toggle Commented Mar 6, 2015 on Thinner and thinner at Arctic Sea Ice
Perhaps we really are entering "Shock News!" territory? Daily NSIDC extent fell by 107,510 km2 yesterday, and the 5 day average is now rapidly diverging from it's closest competitors:
Toggle Commented Mar 6, 2015 on Thinner and thinner at Arctic Sea Ice
Thanks for your kind words Vaughn, and also for your "list" :) It seems appropriate to mention here the discussion on the forum about the distribution of multi-year versus first year ice, the latter of course being thinner. This year the North Pole (currently at least) is surrounded by the first year variety:
Toggle Commented Mar 5, 2015 on Thinner and thinner at Arctic Sea Ice
Bill - Re your final question, it seems unlikely at the moment. Reading your latest addition to that SkS thread reminds me that we really should endeavour to get together around a jar of scrumpy at some point soon! Is there any chance you might be attending the forthcoming Greener Teign meeting with some local prospective parliamentary candidates? http://www.greener-teign.org.uk/?event=quiz-the-candidates There are a few of us down yer who are not "deeply conservative in their political opinions"!
Toggle Commented Mar 3, 2015 on Shock news! at Arctic Sea Ice
This is not really "Shock News", as Neven explains at the top. Nonetheless after a brief hiatus both the NSIDC and IJIS Arctic sea ice extent metrics are once again at the lowest value for the date since their respective records began. Yesterday's IJIS came in this morning at 13,827,443 km2. We'll have to wait a few hours more for the NSIDC number.
Toggle Commented Mar 2, 2015 on Shock news! at Arctic Sea Ice
Kano - Are you sure you're commenting on the correct article? In any event you may wish to read the following thread on the Arctic Sea Ice Forum: Increasing Antarctic Albedo?
Toggle Commented Mar 1, 2015 on Erase and rewind at Arctic Sea Ice
An email is "in the post" Larry. Thanks again.
Toggle Commented Feb 28, 2015 on Shock news! at Arctic Sea Ice
Thanks very much Larry, and I didn't actually mean that remark the way you seem to have taken it! FYI - Our latest guest post, hot off the GWC virtual presses: The Telegraph is Wrong Again on Temperature Adjustments
Toggle Commented Feb 27, 2015 on Shock news! at Arctic Sea Ice