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John Christensen
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The Centre for Ice and Climate at Cph Uni has a nice overview of densification of ice caps: http://www.iceandclimate.nbi.ku.dk/research/flowofice/densification/ Based on this, I agree with Wipneus; the mass gain in Eastern Antarctica is of relatively low density - unless the areas have been impacted by above freezing temperatures during SH summer.
Toggle Commented 10 hours ago on PIOMAS April 2018 at Arctic Sea Ice
On sea ice volume: DMI max SIV possibly reached April 16th slightly above 24K km3 near 2015 level and comfortably below 2004-13 average: http://polarportal.dk/en/sea-ice-and-icebergs/sea-ice-thickness-and-volume/
Toggle Commented 12 hours ago on PIOMAS April 2018 at Arctic Sea Ice
Sorry, let me clarify further, as the 50% can be seen as misleading. Percentage of increased radiative forcing of greenhouse gasses due to human activity: - CO2 (Burning of fossil fuels): 44.9% - N2O, O3 (Engine combustion, industry emissions, chemical solvents): 17.2% - Methane (Various reasons, mainly human inflicted): 14.8% - CO2 (Deforestation): 12.3% - Halocarbons (Non-natural gasses from industry): 10.8%
Toggle Commented Apr 11, 2018 on PIOMAS April 2018 at Arctic Sea Ice
Clueless, The "we could somehow stop" combined with "their folly" sounds a bit schizophrenic, as I assume you are human, living in a house and have a computer. Also, remember that burning of fossil fuels and cement production together is about 50% of the increase in radiative forcing of greenhouse gasses. See changes in radiative forcing: https://en.wikipedia.org/wiki/Greenhouse_gas#Greenhouse_gases And the CO2 cycle: http://www.fao.org/docrep/005/ac836e/AC836E03.htm
Toggle Commented Apr 11, 2018 on PIOMAS April 2018 at Arctic Sea Ice
Thank you for a great update Neven! You did leave out one key element though - the SSW event in late February, which I find is the main reason for the Arctic cooling during March. Michael Mann said this about the SSW event: “This is an anomaly among anomalies. It is far enough outside the historical range that it is worrying – it is a suggestion that there are further surprises in store as we continue to poke the angry beast that is our climate” https://www.theguardian.com/environment/2018/feb/27/arctic-warming-scientists-alarmed-by-crazy-temperature-rises That statement is remarkable for a scientist, assuming he was aware that an SSW event took place. The director of the Earth System Science Center at Penn State University would have been greatly aided by the excellent blog entry by R. Gates in January 2013, which explains causes of these recurring events: http://neven1.typepad.com/blog/2013/04/sudden-stratospheric-warmings-causes-effects.html Either way - and what I have not seen described anywhere - is that subsequent to these SSW events, which occur every 2-3 years, the polar vortex seems to solidify and cause Artic temperatures to drop sharply after the initial warming at surface level. This effect is clearly visible in Zack Labe's chart above, in the DMI 80N temps, and in significantly higher sea ice accretion in following weeks.
Toggle Commented Apr 5, 2018 on PIOMAS April 2018 at Arctic Sea Ice
Hi wayne, I agree with you on the effect of El Nino/La Nina, which is often overlooked. For Arctic weather conditions during summer: - The natural tendency is for low pressures to develop over the Arctic Ocean due to the difference in temperature between cold ocean/ice surface relative to heated surrounding continents. - However, La Nina conditions during early/mid summer increases probability of colder temps and more precipitation in northern US/southern Canada, which again increases probability of a high pressure area developing and persisting in Beaufort and the CAA - exactly as we saw in 2007. The summers of 2007, 2013, 2016, and 2017 follow this pattern well. The summer of 2012 appears to be exceptional, as we had high melting rates, but maybe Neven's old word of wisdom is helpful for summer conditions: "Neither fly nor fish" I believe. El Nino during summer probably increases risk of warm moisture reaching the Arctic, while moisture in the Arctic during neutral ENSO conditions is cold (Again being caused by temporal difference between ice and land). Luckily the ENSO is forecast to become neutral, as you mentioned, which has caused me to reduce the risk of negative ENSO impact on summer 2018 melting: "Most models in the IRI/CPC plume predict La Niña will decay and return to ENSO-neutral during the Northern Hemisphere spring 2018 [Fig. 6]. The forecast consensus similarly favors a transition during the spring, with a continuation of ENSO-neutral conditions through the summer." http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml
Toggle Commented Apr 5, 2018 on Bering goes extreme at Arctic Sea Ice
Hi Rob, Thank you for the reply! Noting your factors (NH snow cover, SIA and SIE), I wonder why sea ice volume wouldn't make the list of significant factors. See 2012 vs 2013: - Sea ice volume (SIV) equal at beginning of melting season - April SIE higher in 2012 than 2013 - Sept. SIE much lower in 2012 than 2013 Sea ice volume or distribution of the volume might have been able to better explain the actual difference in melting. For 2018 compared to 2016 and 2017: - April SIE lower in 2018 than 2016 and 2017 - April SIV (PolarPortal) higher in 2018 than 2016 and 2017 The increased level of compactness/thickness of the sea ice in 2018 IMO should favor a lower level of melting and therefore also relatively higher Sept SIE, so let's see. That said, NH snow cover will probably also be higher in 2018 compared to past couple of years, which then alternatively will explain a reduced melting.. In general, weather patterns that cause low pressures to form over the Arctic Ocean from mid-late May probably will also help retain NH snow cover, although numbers not always reflect that.
Speaking of melting; Rob, what is the timing of your first prediction for Sept SIE?
For an early prediction of the coming melt season, I would see 2018 as a continuation of recent relatively low-melt seasons, due to: 1. NH hemisphere continents (Especially Alaska and Siberia) are heating up quickly 2. Significant cold (-25C and lower) area is confined to northern Greenland, CAA, Siberian coastline and the Arctic Ocean: http://polarportal.dk/en/weather/nbsp/current-weather/ 3. We have at least 1000km3 more sea ice within the same area compared to last year due to thicker sea ice cover in the Arctic Ocean: http://polarportal.dk/en/sea-ice-and-icebergs/sea-ice-thickness-and-volume/ These factors all indicate a high difference between the rising temps on the continents against the cold Arctic Ocean, which tends to increase occurrence of summertime quasi-constant lows over the AO.
Toggle Commented Mar 23, 2018 on PIOMAS March 2018 at Arctic Sea Ice
Back to Arctic temps: Interesting to see how the recent SSW event caused a subsequent stabilization of the Arctic vortex with a stable central Arctic high and DMI 80N reaching seasonable levels for the first time in many months: http://ocean.dmi.dk/arctic/meant80n.uk.php If my memory serves me right we saw a similar return to stable cold Arctic temps in early 2013 following another significant SSW event.
Toggle Commented Mar 20, 2018 on PIOMAS March 2018 at Arctic Sea Ice
On snow-ice, It would appear that DMI's polar portal ( http://polarportal.dk/havis-og-isbjerge/havisens-tykkelse-og-volumen/ ) also does not recognize the snow-ice formation, as February volume growth was low, even with decline towards end of the month. However, for March with lower temps in the central Arctic basin, DMI's volume measure has gone up again, maybe due to snow-ice turning into a more solid state? Historically on snow-ice: Even the accounts of the Fram voyage 1893-96 mentions examples of ice being submerged by snow, but also that it was rare and that winters were dominated by high pressure, dry climate, less wind and ice primarily being formed due to pressure ridges and in open lanes.
Toggle Commented Mar 13, 2018 on PIOMAS March 2018 at Arctic Sea Ice
You're very welcome Neven! ;-)
Toggle Commented Mar 8, 2018 on Talk about unprecedented at Arctic Sea Ice
Hi wayne, I don't disagree; the boundary for sublimation to be possible is probably closer to -25C. In plain words, this just highlights that the snow surface can be diminished during otherwise wintry conditions, and being very different from melting, the latter being associated with above-freezing temperatures. I went through the DMI SMB images of Greenland and noticed slight sublimation occurring January 16-18 as well in north-western Greenland.
Toggle Commented Mar 8, 2018 on Talk about unprecedented at Arctic Sea Ice
"Sublimation is in a way similar to melting, but instead of turning to water, the ice is directly turned into water vapour, right?" Hi Neven, Let me also comment on sublimation: Basically, sublimation is a phenomenon that is possible, when the air temperature is below freezing point and the air pressure is sufficiently low. At air temperatures lower than -20C sublimation of ice becomes nearly impossible, since the air pressure would need to be extremely low, but during winter if you had continuous temperatures of -2 to -10C in your back yard, then you would often observe sublimation when the air pressure drops. Think of the Alps: The snow cover will slowly disappear even at altitudes with constant freezing, as the sporadic passage of low pressure fronts allows frozen water molecules to be converted directly to water moisture. The Föhn wind often causes a sufficient drop in air pressure, when high altitude air masses move quickly down to sea level - especially when the Föhn as in this example from Northern Greenland is accompanied by air temperatures increasing to warmer than -10C. Therefore, for many of the low pressure systems that move quickly across Greenland you will observe precipitation on the 'receiving' side of the ice cap and simultaneously sublimation on the opposite side of the ice cap, if the high altitude air mass is pushed down quickly enough and the freezing is sufficiently weak.
Toggle Commented Mar 8, 2018 on Talk about unprecedented at Arctic Sea Ice
Seems like 2m temps have reached -35C now in tiny spots in Baffin Bay and also near the cost of Laptev Sea.
Toggle Commented Jan 29, 2018 on PIOMAS January 2018 at Arctic Sea Ice
Hi wayne, It seems like a small low should pull out somewhat colder temps into western Baffin Bay from Baffin Island in the next 3-4 days, likely around -35C.
Toggle Commented Jan 26, 2018 on PIOMAS January 2018 at Arctic Sea Ice
Thanks Neven! ;-)
Toggle Commented Jan 8, 2018 on PIOMAS December 2017 at Arctic Sea Ice
Hi AJT, The answer to the question of why we currently have more arctic sea ice than a year ago is found in Neven's PIOMAS updates: The past few months have been colder (Read: Less anomalously warm) in the central Arctic region than they were a year ago during the extremely warm 2016/17 winter. Secondly, heavy snow fall on the sea ice caused by the frequent late fall/early winter storms a year ago further hindered sea ice build-up, while the past few months have seen a much higher degree of clear skies above the ice, enabling a more efficient heat exchange between water/ice and the atmosphere. In the next PIOMAS update I would expect still overall relatively high average sea ice thickness numbers, as area has remained low (Slow sea ice build-up in peripheral seas), while the sea ice volume is growing relatively well in the central Arctic seas.
Toggle Commented Jan 7, 2018 on PIOMAS December 2017 at Arctic Sea Ice
Fortunately, the Arctic sea ice is still faring better than a year ago with a slightly thicker sea ice pack: Sea ice area similar to last year and about 1400-1500km3 more sea ice in the pack.
Toggle Commented Jan 5, 2018 on PIOMAS December 2017 at Arctic Sea Ice
Warmer at the core of the high? I have noticed since yesterday that at the core of the high, the 2m temp is a few degrees higher than in the surrounding area: http://ocean.dmi.dk/arctic/weather/arcticweather.uk.php This seems counterintuitive, so I was wondering if the sensors are being tricked in this situation, or if anyone would know why the near ground temp at the core of a cold high should be higher than the surrounding area?
Toggle Commented Dec 15, 2017 on PIOMAS December 2017 at Arctic Sea Ice
Hi AJT, Here is how it works on Neven's blog: He will post an update on some topic; melting status, monthly PIOMAS, or a specific topic of interest. He then indicates an update to be the open thread like these monthly PIOMAS reviews, where you can stray from the topic of the update - as soon as you stay within the realm of everything Arctic sea ice/climate. I don't mind a few stray comments at all, and this is not my blog, but responded to your notion of an 'open forum', which is not the case for this blog.
Toggle Commented Dec 12, 2017 on PIOMAS December 2017 at Arctic Sea Ice
Regarding ice volume distribution: It seems like the fairly consistent high above the CAB/Laptev in recent weeks is starting to make an impact on ice volume distribution: http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent/ On the Siberian side of the CAB into northern parts of the ESS and Laptev, there seems to be nearly as much thick ice as in the safe haven north of the CAA, something I have not noticed since pre-2007. Given the overall low volume, the ice volume north of CAA must be showing a more significant negative anomaly. If the high continues as is still forecasted, the clockwise rotation of the main pack will pick up speed causing more ice to exit the Arctic via Fram in the coming one/two years - Fram export being also a main culprit of the massive sea ice loss in 1981-82, and contributing in 2007.
Toggle Commented Dec 11, 2017 on PIOMAS December 2017 at Arctic Sea Ice
Hi AJT, Neven's Arctic Sea Ice Blog has never been an open blog to discuss any topic of preference, so please respect that. You can stray for a comment or two, but otherwise need to get back on topic or take the discussion elsewhere.
Toggle Commented Dec 11, 2017 on PIOMAS December 2017 at Arctic Sea Ice
wayne, You wrote Nov. 17: "a very cold CAA CTNP will dominate weather as is for quite some time in the foreseeable future." I commented on Dec. 2, but that was too early, as you said: "wait for the projected time period ends before making a comment" However, in the forecast reaching mid-December I still see the circulation dominated with the Siberian high semi-connected with the high between the Pole and Laptev, so is the foreseeable currently ongoing or have we perhaps not reached it yet?? ;-)
Toggle Commented Dec 11, 2017 on PIOMAS November 2017 at Arctic Sea Ice
Thank you for another great update Neven - and Happy Holidays to you as well! At least it seems like the Alp region is having some early snow this year, but maybe not as far east, as where you live?
Toggle Commented Dec 7, 2017 on PIOMAS December 2017 at Arctic Sea Ice