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pottyprof

Antarctic Ice Discussion

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Ice Shelves Disappearing on Antarctic Peninsula

This image shows ice-front retreat in part of the southern Antarctic Peninsula from 1947 to 2009. USGS scientists are studying coastal and glacier change along the entire Antarctic coastline. The southern portion of the Antarctic Peninsula is one area studied as part of this project, and is summarized in the USGS report, "Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947—2009" (map I—2600—C).

http://www.usgs.gov/...cle.asp?ID=2409

Credit: U.S. Geological Survey

Edited by weather ship

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However bizarre it first seems the midsummer sun (24hrs) over the Arctic delivers the biggest wallop of energy (per sq metre of surface) than anywhere on the planet!

http://www.applet-magic.com/insolation.htm (scroll down to the table and check the summer solstice figures)

around 12.64 Kw/m2 (the equator max's out at 10.22Kw/m2)

Yes but for how long... six weeks? The equator would be at that rate 52 weeks a year.

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Yes but for how long... six weeks? The equator would be at that rate 52 weeks a year.

12 weeks or more? I know it appears a small impact but when you look at what being in 'positive' values does to the ice you can't just dismiss it? If you then take a planet that has reflected most of that input back into space (for as long as I'm aware) then start to soak up 8/10ths of it it can't be ignored...can it???

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Yes but for how long... six weeks? The equator would be at that rate 52 weeks a year.

Actually the equator can be a bit of a red herring regarding solar radiation. Between 6 deg.N and 6 deg.S the sun's rays remain almost vertically overhead for only 30 days during each of the spring and autumn equinoxes, allowing little time for any large build-up of surface heat and high temperatures. On the other hand, between 17.5 and 23.5° latitude the sun's rays shine down almost vertically for 86 consecutive days during the period of the solstice. This longer sustained period, combined with the fact that the tropics experience longer days than at the equator, makes the maximum zones of heating occur nearer the tropics than the equator.

Edited by weather ship

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Don't be silly BFTP! This is the beggining of the summer 'breakup'.

The new moon tides have helped loosen the edges of the pack which are now floating free in the southern oceans.

Don't take my word for it though , check out MODIS;

http://rapidfire.sci.gsfc.nasa.gov/realtime/2010282/

and see for yourself?

When we have near realtime imges would it not make sense to 'have a look' at what is occuring rather than work up theories?

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Don't be silly BFTP! This is the beggining of the summer 'breakup'.

The new moon tides have helped loosen the edges of the pack which are now floating free in the southern oceans.

Don't take my word for it though , check out MODIS;

http://rapidfire.sci.gsfc.nasa.gov/realtime/2010282/

and see for yourself?

When we have near realtime imges would it not make sense to 'have a look' at what is occuring rather than work up theories?

Would the new moon induced fragmentation not occur around this time of year every few years anyway and thus be included as part of the long term average? It's hardly a novel occurrence...

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Don't be silly BFTP! This is the beggining of the summer 'breakup'.

The new moon tides have helped loosen the edges of the pack which are now floating free in the southern oceans.

Don't take my word for it though , check out MODIS;

http://rapidfire.sci...altime/2010282/

and see for yourself?

When we have near realtime imges would it not make sense to 'have a look' at what is occuring rather than work up theories?

i love your manners:closedeyes:

i think BFTP has an extremely good point but then anything other than a recovery keeps you intrested gw,

but we shall see shame things are not going to plan in both hemispheres!...i think the solar minimum is going to put a spanner in the works of the doom extremists.

as for the antarctic never really been concerned and am certainly not concerned now,

both pole regions are on the up:drinks::yahoo:

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Don't be silly BFTP! This is the beggining of the summer 'breakup'.

The new moon tides have helped loosen the edges of the pack which are now floating free in the southern oceans.

Don't take my word for it though , check out MODIS;

http://rapidfire.sci...altime/2010282/

and see for yourself?

When we have near realtime imges would it not make sense to 'have a look' at what is occuring rather than work up theories?

This cannot be a serious post .......... is it !!!!?

Extent looking good .....

Posted Image

Anomaly chart showing the past 30 year increasing trend.

Posted Image

Latest image looking healthy !!!

Posted Image

Y.S

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Can we not go down the line of insults, put downs and the like please? There is no need for it. We are operating a zero tolerance on that kind of thing.

Thanks in advance.

:)

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Interesting, that is some leap. We seeing Nina start to bite? Big northern increases and a leap down under.

BFTP

Is that the satisfactory explantion why we are 1m above long term averages ?.

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Ho W.S.!

The increased precipitation across the Peninsula (and reduced rainfall in SW Australia) were linked to a change in atmospheric circulation driven by the Ozone hole in a paper this Spring (? I linked to it but it would be on the 'old forum') , we've always linked the 'warming' to the increased snowfall we're seeing across the peninsula so the 'freshening' of this area of the Southern oceans should come as no surprise to us. The 'slush' and fresh water will obviously impact the temps where this surface skim will freeze (and find it's way onto the extent charts) but this is not 'good ice' and ,as we saw in mid seasons 1 million melt in a week, any storms will 'wash away' this skinny ice (and mix the surface leading to a period where the ice will not form at the same elevated temps).

It would be interesting to see where the positive anoms lie. I would guess around the edges of the Weddell Sea and the area facing Ross?

As the Catlin base camp saw this year the Arctic is also becoming more prone to the perils of 'rain' across the ice in spring and this will, if temps continue to rise, speed up ice loss in spring exposing more water for longer to the sun(pour water on ice as opposed to snow and see what happens!).

As an aside I see the neg sea temp anoms facing Ross are back again this year?

http://www.osdpd.noaa.gov/data/sst/anomaly/2010/anomnight.10.11.2010.gif

I have had concerns (over the past 5 years) at this spring/early summer anom and have ,in the past, noted it's progress towards the tropics as it encounters undersea ridges/sea mounts and surfaces. Keep an eye on the 'cold anoms' and see how it progresses over the next 2 months. If this represents 'outflow' then we do have problems with E.A.I.S. (and it's plumbing) if it is just 'melt' of the ice then we have no worries apart from why other sea areas do not show the same?

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Going by this there's been a cooling trend around Antarctica's oceans...

http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2010&month_last=8&sat=-1&sst=1&type=trends&mean_gen=1212&year1=1980&year2=2009&base1=1951&base2=1980&radius=250&pol=pol

That additional precipitation has yet another effect that helps increase sea ice: It lowers the salinity of the surface water, which slows the melting of sea ice, Liu explained

I dunno. How is it that increased precipitation in the Arctic prevents the ice from growing in thickness and helps it melt quicker, but increased precipitation in Antarctica lowers the waters salinity, helping the ice to melt slower? Also, the minima for Antarctic ice hasn't changed, it's the maxima that have been on the rise, so how does a slow down in the melt rate affect that?

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I'll respond to this.

There is a quote of 30 years ice growth in those links and might I suggest that the PDO and perturbation cycle both of 30 and 36 yrs length in cycle could account for this. During =ve phases the NH ice suffers and SH gains and during -ve phases we see the reverse happening. We have since feb 07 changed from El Nino perturbation to La Nina perturbation and PDO similar time. This scenario also fits snugly with timings but will probably need another cycle of observations.

All I can see at present is that the ice situation and deep Pacific cooling [with no milding out] are totally at odds with GWs thoughts and projections.

BFTP

Edited by BLAST FROM THE PAST

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NDS, Hi!

Are you not misconstruing the article? I took it to mean that the 'freshening' of the surface layer meant it would freeze at higher temps therefore expanding the 'zone of freezing' and allowing earlier freezing of the surface in other areas? As we see with 'melt water pools' on sea ice freezing well before the surrounding 'salty' waters?

If the increased precipitation from the Peninsula extends out into Weddell we could expect to see earlier re-freeze there and an extension of that ice zone into the southern oceans ( thus expanding the 'extent' of ice cover?) The peninsula 'juts out' into the southern ocean and throws the circumpolar currents further out into the southern ocean (and makes some interesting patterns in the waters once the ice melts back with whirls and eddies in that frothy/floury water that remains post melt?)

There is also another type of ice consisting of brine filled snow that becomes frozen into a porous sea ice. This too would appear on extent charts but does not have the qualities of ice proper. Come the full onset of melt do not be surprised to see the peripheral pack in front of Weddell/Ross vanish at a rate of knots.

Talking of melt we have that large berg (from the rammed off Glacial tongue?) to keep an eye on this southern summer though ,so far,fears of it's interference in 're-freeze' appear to have been unfounded?

Edited by Gray-Wolf

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NDS, Hi!

Are you not misconstruing the article? I took it to mean that the 'freshening' of the surface layer meant it would freeze at higher temps therefore expanding the 'zone of freezing' and allowing earlier freezing of the surface in other areas? As we see with 'melt water pools' on sea ice freezing well before the surrounding 'salty' waters?

If the increased precipitation from the Peninsula extends out into Weddell we could expect to see earlier re-freeze there and an extension of that ice zone into the southern oceans ( thus expanding the 'extent' of ice cover?) The peninsula 'juts out' into the southern ocean and throws the circumpolar currents further out into the southern ocean (and makes some interesting patterns in the waters once the ice melts back with whirls and eddies in that frothy/floury water that remains post melt?)

There is also another type of ice consisting of brine filled snow that becomes frozen into a porous sea ice. This too would appear on extent charts but does not have the qualities of ice proper. Come the full onset of melt do not be surprised to see the peripheral pack in front of Weddell/Ross vanish at a rate of knots.

Talking of melt we have that large berg (from the rammed off Glacial tongue?) to keep an eye on this southern summer though ,so far,fears of it's interference in 're-freeze' appear to have been unfounded?

Hello GW,

Not too sure how I can be misconstruing it. I did quote where he said the it would slow the melt, unless he was mis-quoted or something?

I have no problem with the extra precip "freshening up" the sea surface, allowing for an easier re-freeze. But with all the snow about, falling on the sea ice, would we not just get weak thin ice (like in the Arctic) that melts out quickly and not these large extents we've been getting the last few years?

I just fail to see how one thing can be increasing Arctic sea ice melt yet at the same time be greatly helping Antarctic ice growth. I know they're 2 different systems, but the mechanism by the the extra precip works should be roughly the same in each hemisphere, no?

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That's my understanding of it NDS, I know the two systems are very different (one an enclosed ocean the other a continent surrounded by ocean) but sea water is sea water isn't it?

As such (along with you?) I can see a 'slush layer' on the surface aiding freezing in the first instance and also that a 'brine filled sponge' of ice would melt out faster but that has to be true in both oceans doesn't it?

If we have increased/augmented precipitation in both areas (north and south) then surely we can apply the same basic physical properties to both areas?

The recent paper discounting that the 'ozone hole' has helped Antarctic by allowing Antarctica to exist in 'splendid isolation' (protected from the general warming) by a faster circumpolar wind and current does have me scratching my Noggin a bit though. If this 'fact'??? is removed then what would explain the current situation?

My time with a lamp and beach volley ball has cleared my head over why things like the mid Holocene optimum was a northern event (and that we can have this 'see saw' effect driven by axial tilt) but what of this when we have a circular orbit and a 'balanced' tilt allowing both north and south equal advantage/disadvantage???

Anyhoo's , as with the 'Greenland mass loss' paper I'll await independent confirmation of these findings (I've not heard the team making the claims about the lack of impact from the hole saying that their evidence is so scant as to render 'replication' of their results impossible) before i re-grapple with the problem (surely the overcoming of the current by basal warm waters and the observation of 'warmer air' above Antarctica confirms that something has been keeping the 'warm out' for 30 odd years?).

So, the only way I can see increased precipitation making a difference to ice levels is by the processes I've outlined (fresh water freezing at higher temps than salt water) and until some tells me this is wrong I'll stay with that!

EDIT: Sorry NDS ,rambling mode!

I haven't managed to see ice hanging around any longer than 'normal'? The high levels of ice seem to melt away in orderly fashion (as we are about to see?)

Edited by Gray-Wolf

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If the increased precipitation from the Peninsula extends out into Weddell we could expect to see earlier re-freeze there and an extension of that ice zone into the southern oceans ( thus expanding the 'extent' of ice cover?) The peninsula 'juts out' into the southern ocean and throws the circumpolar currents further out into the southern ocean (and makes some interesting patterns in the waters once the ice melts back with whirls and eddies in that frothy/floury water that remains post melt?)

Have you a link to the last 30yrs of preciption figures across the whole of Antartica and surrounding regions so we can look at the 'theory' for ice growth.

Ice growth isn't restricted to one part

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Have you a link to the last 30yrs of preciption figures across the whole of Antartica and surrounding regions so we can look at the 'theory' for ice growth.

Ice growth isn't restricted to one part

This what you're looking for?

post-6901-077981100 1286911275_thumb.png

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Surely both those 'facts' can't be right? Unless, of course, the positive anoms balance out the negatives?

You can see a large anom opposite the tip of the peninsula and ,remembering the Circumpolar current will take the ice from there across Weddell and onward, you can see how this could impact this 'strip' of ocean come re-freeze in April(ish) and 'push out' the extent beyond the protection of the Peninsula (for it to be stripped away come the first storm as we saw with the million loss earlier this season).

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Surely both those 'facts' can't be right? Unless, of course, the positive anoms balance out the negatives?

Surely ones looking at Antartica (the land mass) the other includes the surrounding oceans where we see greatest varibility.

Whats the varibility in the Artic in the last 50yrs to compare

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Interesting. Perhaps the mechanism that caused the Wilkins Ice Shelf collapse.

Elephant seals recruited as field researchers have uncovered new evidence of what may have caused the dramatic collapse of an Antarctic ice shelf two years ago.

Wearing tracking tags, the deep-diving mammals mapped the seabed near the Wilkins Ice Shelf, which is the size of Jamaica but recently began to disintegrate. They discovered channels that deflect warm water towards the ice.

http://www.thetimes.co.uk/tto/environment/article2775724.ece

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http://www.physorg.com/news/2010-10-elephant-antarctic-seafloor.html

Seemed to need to pay for the Times piece so here is another 'version'.

The 'seals in bath-caps' had been noting an increase in water temps around this coast for a while. up until this the circumpolar current (via the Coriolis affect) had effectively formed a barrier to warm water ingress from the southern oceans so we need to ask "Why now?".

Has the circumpolar current slowed sufficiently to allow ingress or has the temp difference become so marked as to 'tip the balance' and force the warmer water through?

Both scenarios are a worry as this 'warm water' was noted travelling around the coast from the peninsula towards the Ross Embayment. Should similar happen at Ross we could rapidly find out what tolerances the shelf has for frontal loss of the shelf. How much can be 'floated off' by basal melt before the crush of ice from behind pushes the hole of the shelf free?

Though the WAIS is a great concern loss of Ross (or partial loss) frees up the EAIS's main drain glaciers and would drive rapid sea level rise (which in turn would place mechanical pressure on the other ,remaining, shelfs).

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