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'the high of 1041 minus a low of 980 hPa is a pressure gradient of 61 hPa. That is the pressure difference, the gradient is a different beast introduced to the physical sciences in 1873 or so by JC Maxwell. To get a rough measure of the steepness or rapidity of change, the 61 would have to be divided by the distance separating the high and low. Atmospheric pressure is a scalar field defined in three dimensions. The gradient of pressure is a vector field pointing at the direction of most rapid change. The excellent map provided above uses colors to show the various pressures and contour lines to show isobars (concentric shells of constant pressures). The gradient is only shown by implication: the perpendiculars to the surfaces of these shells. Its line integral shows the direction of air flow. You'll find the same idea all over the forums in the oceanography and ice sheet sections. Somewhere in there I collected the 30-odd iso-whatevers that are used somewhere in climate science. Humpty-Dumpty tried an alternative but it doesn't work.
Toggle Commented Aug 31, 2016 on ASI 2016 update 5: big cyclone at Arctic Sea Ice
The thing that strikes me is here we are, the 2nd of June only 2016 and no one in the scientific community has the slightest physical basis for issuing reassurances that this melt season won't end badly. Very badly. Without any need to invoke improbable weather patterns or rare storm events. Just unfortunate but unremarkable combinations of business as usual. Conditions we have seen in numerous times in recent years. This is no way to manage a planet. Sure, we might slide by another year or two but the downside risk even for one year is colossally disproportionate. The burden of proof is not on us to prove this Sept will be a fiasco but on policy setters to prove the next twenty won't. That's the essence of the precautionary principle.
Toggle Commented Jun 2, 2016 on ASI 2016 update 1: both sides at Arctic Sea Ice
This sea ice portal ( is quite well done and very effective at serving Cryosat-2 data either as graphic or as underlying data. The netCDF format can be opened in with free Panoply with no need for matlab or command line. The originals for these graphics are quite generous, 3747 3747 pixel pngs. They crop quite nicely to a more manageable 1400x1400 for the Arctic Ocean. It is easy to make a black landmask by subtracting two images. I would suggest to them an opt-out for the lat,lon graticule overlay. These are few people who do not already have access to a globe. Better to provide mouse-over lat,lon as done on so many other sites. Erstaunlicherweise ist die Palette ganz falsch für wissenschaftliche Zwecke: the bins do not correspond to metric divisions and it does not drop to a linear grayscale. This is only 6-bit data (64 bins) after all. It is far better to be able to explore time series data intuitively as graphics. Later you can go back and repeat the useful manipulations in netCDF numeric arrays.
I enlarged and animated the six years of February Cryosat-2 that Neven posted above ...,1493.msg74719.html#msg74719
Aaron, we mustn't talk about methane, no matter how bad it gets nor how easily it could be reduced (leaks, beef, rice), or we risk a good spanking from the C02-only narrative enforcement. (humor?) There was a group at MIT that was totaled up all the greenhouse gases, not just carbon dioxide and methane. I've misplaced the link and don't recall if they update it in real time. There were some interesting items in there, like illegal fluoro refrigerants still widely manufactured in a large country located between Pakistan and Bangladesh.
Toggle Commented Apr 21, 2016 on Beaufort quick update at Arctic Sea Ice
Nice work by Andreas T! I posted some enhanced animations of ice melting into the warm ocean current west of Svalbard along with various simultaneous resources from nullschool such as a sea surface temperature anomaly animation with sensitized palette.,1504.msg74474.html#msg74474
Toggle Commented Apr 21, 2016 on Meanwhile, on the other side at Arctic Sea Ice
Ouch !@?... the animation below shows the details that are actually available from Lance-Modis for day 106 of this year at their top 1 km resolution true color (after some processing). The second frame flashes in cloud cover taken from bands 367. You may have to click over to the forum link and click again on the static picture to see at full size.,416.msg73993.html#msg73993
Toggle Commented Apr 16, 2016 on Beaufort quick update at Arctic Sea Ice
Look a little deeper, that text is copied word-for-word from the pull-down itinerary for Cambridge Bay in the CAA. It is also the default text for a dozen other slow days. I'm guessing they fill it in later with cruise-specific outings -- take a selfie with your arm around a real Eskimo? shop for antique ivory dug from a graveyard? shoot a polar bear from a zodiac? buy real tanzanite earrings? harpoon a narwal from a helicopter? Make margarita iced from a real Jakobshavn iceberg? There is no money to be made from a bare-bones cruise, it's all about the add-ons. They can't simply super-size the french fries since ample food is provided. This is not an expensive cruise, considering. The people will just an ordinary cross-section of humanity, not the cast from Bilderberg, Davos, Bohemia Grove or Trilateral Commission.
I'm thinking we should maybe crowd-source your passage so that you can tell your story in the form of an evening celebrity lecture? If you plan on being accompanied by a 'Mrs. Neven', the best fit socially is if she is 25-30 years younger. "Aboard the most award-winning ships at sea, your story can be written exactly as you wish: pamper yourself at the Feng Shui-inspired Crystal Spa, work-out at our state-of-the-art fitness center or Walk-on-Water along our 360º Promenade Deck; learn how to translate your story into a movie with USC’s School of Cinematic Arts Digital Filmmaking class at our Creative Learning Institut; Or learn about art, history and worldly destinations with our engaging celebrity entertainers and speakers with our Crystal Visions Enrichment Program; sneak away to watch recently-released movies in the Hollywood Theatre, shop our luxury boutiques, or simply lounge poolside while our attentive crew caters to your every whim. From mat Pilates and yoga to PGA golf instruction and paddle tennis on full-size courts, today is all about you. As evening arrives, dine on the renowned culinary creations of Nobu Matsuhisa, and Crystal’s own acclaimed chefs with new Modern Cuisine and Global Inspired menus, enjoy special wine-makers dinners, breakout new production shows, intimate lounges, a pulsing dance club or our action-packed Crystal Casino. The choices as always aboard the World’s Best are yours. How will you write your story on board?"
VaughnA brings up a potentially significant positive feedback mechanism for more rapid metabolism of thawed anaerobic permafrost. We’re all familiar with the steaming hot pile of wet autumn leaves and spontaneous combustion of oily rags. The first is self-limiting as the temperature comes to exceed microbial growth tolerances; the latter involves direct oxidation of organic solvents by molecular oxygen. Both are irrelevant to methane production from permafrost which requires not only strict anaerobiosis (lest the nickel catylyst in F430 be poisoned) but also exhaustion of other terminal electron acceptors such as sulfate, ferric iron and nitrate. The carbon sources in peat soils, though already more oxidized than monosaccharide, are abundant, so not likely rate-limiting to archael doubling times -- it is more the number of ATP's that can be made from a molecule of say glucose (which drops from ~38 with O2 around to 1-2 from tannic acid in a fermentative process. Methanogenesis, the final stage of decomposition of organic matter. needs carbon dioxide (or acetate) as electron acceptor and the former will be abundant. Metabolism does indeed move faster at higher temperature in accordance with the Q10 (Arrhenius, 1889) but the effect is limited: a 10º C rise will only halve the doubling time of a facultative psychrophil. A microbe really specialized to low temperatures will struggle at higher temperatures. Thus while the effect is real -- microbial growth raises temperature fostering more rapid growth which furthers temperature increase -- but it will not be a runaway situation in thawing permafrost whose heat capacity (responsiveness to metabolic heat input) is very large relative to the slow inputs that can be expected.
jdallen has provided what I perceive as the correct overview on this very unusual storm while R. Scribbler and KO'N have provided a start on quantitating rain-to-ice and air-to-ice heat transfer respectively. However we are still far from any specific numbers on the magnitude of the overall effect -- if the +2ºC rain volume north of Svalbard was extensive and this storm proves not a one-off event, hoping for compensatory feedback is merely whistling in the dark. Off-season rain-on-ice has proven absolutely catastrophic for western Greenland via an altogether different mechanism: a week of warm wet weather in late August 2011 overwhelmed the ice sheet's basal drainage system for 140 km into the ice sheet interior, literally hydraulically lifting the ice sheet up off its bed, reducing basal friction and sending it on its way to the sea, according to Prof Alun Hubbard [Nature Geoscience, July 2015 DOI: 10.1038/ngeo2482] The drastic rain-on-snow floods in the western US have yet another physical basis: “One of the main misconceptions is that either the rain falls and washes the snow away, or that heat from the rain is melting the snow,” said Nicholas Wayand, a UW doctoral student. Instead, it’s the warm, humid air surrounding the drops that is most to blame for the melting -- moisture in the air condenses on the cold snow just like water droplets form on a cold drink can. The energy released when the humid air condenses is absorbed by the snow. Rainstorms also blows warmer air across the snow to melt its surface. These two processes provide 60 to 90 percent of the energy for melting.
The animation consists of 181 frames. To keep the file size down, the authors saved in 'optimize' gif mode, which means two things: first, only the (very small) change between successive frames is saved in the later frame. The lossless LZW compression used clobbers the blank areas of these change-only frames. Second, to make the optimized animation play smoothly, it's been incorrectly defaulted to 0 milliseconds delay between frames so it will play as fast as your CPU will allow and fool the eye with the gutted out intermediate frames. This is a bug in the gif standard as it can totally hog a visitor's CPU as it loops. The option is over-ridden in good animation software which will require a minimum frame delay of 10 ms or more. You can de-optimize the animation with a single Gimp command, or on a mac simply view in Preview which does this by default (for capturing a frame or two of interest). Scientific journals do not use animated gifs so much but more commonly .mov which don't run on their own but have a slider that allows you rapid back and forth. The original GIF89a spec doesn't loop. A loop counter was added later by Netscape Navigator 2.0 though most animated gif loop indefinitely. You can still set the loop count in ImageJ but Gimp only offers once or indefinite. The gif spec really needs to be fixed. It would not be rocket science to add a speed controller and step-through/save frames for viewers.
2008? John C, you might want to look at Holland's more recent papers, especially the 2015: Oceanic Boundary Conditions for Jakobshavn Glacier. Part I: Variability and Renewal of Ilulissat Icefjord Waters, 2001–14 CV Gladish et al Oceanic Boundary Conditions for Jakobshavn Glacier. Part II: Provenance and Sources of Variability of Disko Bay and Ilulissat Icefjord Waters, 1990–2011 CV Gladish, DM Holland…
Toggle Commented Aug 18, 2015 on Jakobshavn record retreat at Arctic Sea Ice
Tenney, I posted a bunch of time series animations today that include the north-northeast side of the south branch, quite an interesting and active area Start with the overview and finish with a more focused view:,154.msg61008.html#msg61008
Toggle Commented Aug 18, 2015 on Jakobshavn record retreat at Arctic Sea Ice
We only have this dated to a 48 hour interval. If, like in Chasing Ice, it all happened in 45 minutes, there would have been a monumental series of tsunamis coming down the fjord as mile-high bergs rolled over on their sides. Most of the scientific instrumentation is on the rock peninsula on the south side, which according to google earth elevations is ~250 meters or more above sea level, so gear and observers are not at risk. The north side has had a real-time, open source web cam run by Dr. Holland of NYU Courant to monitor the fjord (not so much the calving front). If someone feels like chasing our time frame down on this to clarify the event sequence, that would be a great help.
Toggle Commented Aug 17, 2015 on Jakobshavn record retreat at Arctic Sea Ice
What happens next? Wait and see -- there's still 6 weeks left in the season (per 2014). There's no specific guidance on this from the many Jakobshavn journal articles published to date and we certainly don't know any better over at the forum. However rubikscube posted some initial thoughts on what "crossing the sill" might mean for future retreat and I elaborated on the two main scenarios, starting at:,154.msg60950.html#msg60950
Toggle Commented Aug 17, 2015 on Jakobshavn record retreat at Arctic Sea Ice
steven, I recommend the DMI site as a much fast and better way of watching Greenland than Eosdis worldview. Espen and I already processed way back the underlying Modis images Eosdis is now projecting, the 15-08-2015 Terra and 16-08-2015 Aqua. David, please always include a url with a question -- there are several hundred gifs on the Jakobshavn forum. The telltale signs of a calving might not be seen unless you click on the animation to get it rolling. We don't use gifs except for animations (jpg or png otherwise). Watch the dates and look for calving front changes in the later date.
Toggle Commented Aug 17, 2015 on Jakobshavn record retreat at Arctic Sea Ice
I recalculated the area calved as 6.3 km2 and the volume calved as 8.8 km3 (assuming 1400 m average depth of ice). This is done by counting pixels and multiplying by the resolution (area) of a (square) pixel. I see few prospects for making this any more accurate: it is hard to tell what has calved but hasn't fallen away, is about to calve, and where the white is a vertical face or just a gnarly crevassed area at the front. Similarly for volume, it would be difficult to subtract off air in deep near-calving front crevasses. None of this ice was floating so it all goes to sea level rise: 8.83 * 2.78 = 24.5 microns (0.0000245 meters, or 0.0245 millimeters, acording to this site: Also, steven v notes above (?) for the 2014 comparison, that date was September 28th. I fixed the Landsat path,row mismatch and re-did the comparison at 7.5 m (instead of Espen's initial 30 m).,154.msg60953.html#msg60953 We actually commented on unusual crevasse pre-conditioning beginning on the 14th but the event itself was even larger.,154.msg60773.html#msg60773 Nukefix also has made a very important contribution here in getting Sentinel into Landsat-matching mercator coordinates, near the links above. This allows us to monitor the calving front at shorter intervals and also under dark or cloudy conditions.
Toggle Commented Aug 17, 2015 on Jakobshavn record retreat at Arctic Sea Ice
George Ph notes: "A new James Hansen paper with 12 co-authors... Lots of press reporting, not one person links to or quotes from the article.' Because no one has seen the article. They screwed up royally by sending out the press release without an embargo contingent on article release. It is not available at Hansen's scholarly publication sites nor at ResearchGate. It is supposed to be released sometime "this week" at ACPD; by then the media cycle will have moved on, way on. We'd all be hollering foul play if the Southern Corp does this with Willie Soon's Nov 2015 paper. The link to the paper should be:
Toggle Commented Jul 22, 2015 on Junction June 2015 at Arctic Sea Ice
"Else we'd have problems of the Mississippi completely freezing over to the mouth, like it did in 1912." Actually in that year it didn't. Nor in any other year in recorded history. The surface froze down to the mouth of its confluence with the Ohio River in Jan 1912 which is still a thousand miles (1600 km) north of the mouth of the Mississippi River at the Gulf of Mexico. Downstream ice jams are not unusual at bridge pilings and piers at the latitude of St. Louis. This ice originates far to the north, not locally; the river continues to flow underneath.
"Nor does this explain current happenings in the Arctic." I re-processed the 19 Jul 15 Bremen AMSR2 that NeilT mentions above ... it's instructive what all poleward incursions into sea ice concentration are there but cannot be seen in the original.;topic=165.0;attach=18517;image
"My image processing pipeline uses ImageMagick. Can ImageJ2 likewise be used in "batch mode"? Doing everything manually would take forever" Yes, ImageJ has a macro recorder. So you just walk through enhancement steps one time and save as a menu tool. Then just apply the tool to a target folder, no need to open all the files, no need to learn or view a scripting language. See the ImageJ forum,165.msg57298.html#msg57298 However ImageMagick surely has this too, perhaps less conveniently. It also has the particular 'exponentiate image' command I used on the U Hamburg images (and much more, see The issue here really is what overall enhancements are fit for purpose. Here 'exp' works to exaggerate the low end of AMSR2 ice concentration. It's far from a unique way of over-weighting weak pixels but does not destroy pointwise data integrity the way contrast enhancement would. It's harmless in the sense of being invertible by 'log'. Both exp and contrast are fit for purpose if that is education or early alert to change. However exp is also suitable for building a tool that detects and measures swell damage to Beauford sea ice. That is, most of the time there won't be a research ship stationed there so we have to work with online products. WaveWatch III provides swell and wave data north of the Bering Straits while nullschool and others provide wind and cyclonic pressures, what's left is to determine the aftermath. Since that is initially floe size reduction, to the degree that shows up at all, it will be in more faint blue pixels of the Hamburg maps on the windward side. With an event strongly suspected, it is then feasible to dig into their raw x,y numbers. You have a good start on this at and associated links.
Nice work, Jim. To draw out the contrast between weaker blues and background white, I exponentiated the palette using a command over in ImageJ2, as explained in that developer forum.;topic=165.0;attach=18437;image
And what exactly will Wadhams do the Bering Sea this September? At $50,000+ per day for the Sikuliaq, there has to be a plan. And that plan has to have been in a grant application. And those have be to in the public domain, this is not something that ONR fwould put on ice (classify) … Mmmm, google search could hardly miss on ‘sikuliaq + wadhams' … ok here it is, Wow, 57 pages, 20 co-authors, journal quality. This is a must-read for folks posting on Arctic sea ice prediction. Sea State and Boundary Layer Physics of the Emerging Arctic Ocean The Office of Naval Research initiated a Department Research Initiative (DRI) titled Sea State and Boundary Layer Physics of the Emerging Arctic Ocean. The central hypothesis of the ‘Sea State’ DRI is that surface waves now have a much greater role in the contemporary Arctic Ocean. Indeed, the entire Arctic Ocean in summer may soon resemble a marginal ice zone (MIZ), where waves propagate through the ice pack and affect the evolution of sea ice over large scales. This large-scale pattern feeds back, as wave generation is controlled by the amount of open water fetch. At smaller scales, waves and ice interact to attenuate and scatter the waves while simultaneously fracturing ice into ever changing floe size and thickness distributions. Further complicating these processes are forcing by winds and surface fluxes from the ocean to the atmosphere, which are expected to increase with heightened storm activity in the region. The marginal open seas provide new opportunities and new problems. Navigation and other maritime activities become possible, but waves, storm surges and coastal erosion will likely increase. Air–sea interactions enter a completely new regime, with momentum, energy, heat, gas, and moisture fluxes being moderated or produced by the waves, and impacting upper-ocean mixing. Science objectives: • Develop a sea state climatology for the Arctic Ocean • Improve wave forecasting in the presence of sea ice • Improve theory of wave attenuation/scattering in the sea ice cover • Apply wave–ice interactions directly in integrated arctic system models • Understand heat and mass fluxes in the air–sea–ice system The DRI will focus on arctic conditions during the late summer and early autumn, especially the freeze-up of the Beaufort and Chukchi seas, to capture the strongest storms and maximum open water. This focus also complements the Marginal Ice Zone DRI (MIZ-DRI) that is studying the summer breakup and ice retreat. Field observations will be collected primarily during a cruise in the fall of 2015, supplemented by long-term moorings and autonomous platforms….
Toggle Commented Jul 12, 2015 on PIOMAS July 2015 at Arctic Sea Ice
>> "a poof! and it's all gone year" or PW's forecast That's my view as well. Swells from a bad cyclone when all the weather ducks have been in a row and it's in a sudden death spiral. Jim, not noticed PMs, maybe better if they blinked incessantly. Right now I am tied down with peak-season Greenland. Or rather, tied down trying to get Espen tied down on one of the large floating laboratories in the fjord to sample Jakobshavn ice calvings. I’ve added the 2009 article you cite above from your excellent web resource. Co-author MG Asplin cites this paper in both the 2012 and 2014 incident reports provided above. (I always read backwards from the most recent!) Surely the Sikuliaq needs a press officer onboard blogging the September trip — you would be eminently well-qualified. Have you asked? “What makes Sikuliaq unique is that it can operate year-round in first-year ice,” Oliver said, “and even some multiyear ice.” He declined to call it an icebreaker, preferring ice-capable. With half the heft and horsepower of the Healy, Sikuliaq doesn’t have the muscle to go through heavy ice packs, he said. Nonetheless, it can work in the Bering Sea in winter and in Arctic and Antarctic waters in summer. The Sikuliaq will be particularly adept at maneuvering in marginal ice zones where you have leads and broken floes, Oliver said. Enhanced maneuverability is made possible by the ship’s propulsion system (azimuthing Z-drive). “It has no rudders, no conventional shafting or screws,” Oliver explained. The system is called. [Oliver was commanding officer on the Healy.] By the way, I applaud what you, Chris, Temmey, Scribler, Wipneus and others are doing on the web sites side, even though in a parallel troll-free universe it could simply be assimilated into factual wikipedia page updates. Methane … the more coverage on that the better. The CO2 modellers are dead wrong here. Mocking and suppression of Shakhova and Semileto’s research, while citing bogus paleo — this has no place in science. One of the CO2 fellow-travellers (sputniks) started a prominent article saying the Siberian tundra holes smelled like methane [which of course is odorless, just look at the formula]. How can someone at this level of incompetence even begin to model free radical photochemistry in the upper atmosphere under changing conditions?!? That’s scattering theory on top of rather serious quantum chemistry kinetics. This is by far the most difficult area in climate science. … (Perennial pack ice in the southern Beaufort Sea was not as it appeared in the summer of 2009)
Toggle Commented Jul 12, 2015 on PIOMAS July 2015 at Arctic Sea Ice