Tasboy
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Posts posted by Tasboy
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GW..
Extent has gone up by another 60k KSq as of 1st Oct. That is 5 days on the trot of increases. Is that classified as a rally? Its now at a max for this season. So no max yet.
We may now have a chance of the latest max recorded soon. These values are according to NSIDC. I will check Tasboy's figures now.
I am not trying to make a point, except that this year has been extremely variable. Swinging around wildly, but the fact that it seems to be still increasing even this late in the season means what?
MIA
Yep, agree. It's been quite variable.
My take is that sea ice distribution has been responding over the last few months to the El Nino (via synoptic wind pattern), after having been free from ENSO constraints for the last few years.
The build up of sea ice in the Bellingshausen and Amundsen seas late in the season (it's the only place where sea ice is beyond it's climatological mean at the moment - http://www.cawcr.gov.au/staff/preid/seaice/gsfc_extent_hov_anom.html) often means that there is a chance that this "excess" sea ice may break over the Peninsula (much like a wave) as it is caught up in the circumpolar current and advects east. From there it is caught in the Weddell Sea gyre where it may expand further. I think that's what's happening at the moment (guess at this stage).
Sea surface temperatures in the B&S seas have also been colder than normal - at record lows for this time of the year as it works out. Mmmm, interesting...
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Whoops ! my bad. Must be showing break up at the ice edge? Is it 15 or 30% counting as '100%' do you know?
Happens!
15% is counted as ice edge. And yes, there's lots of break up around the edge, pretty much right around the continent.
Unusually, there's a lot of relatively sparse ice around the Peninsular and B&A seas at the moment.
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Speaking of interesting...
Sea-ice extent seems to have had a late rally. The annual daily maximum is now in late September, rather than on the 5th September as previously mentioned.
http://www.cawcr.gov.au/staff/preid/seaice/sea_ice_table_extent.html
(It should be noted that there is a small problem with the satellite data for the 29th)
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Quite a feat to make average conditions seem like a portent of doom.
I think you are misinterpreting what GW has expressed.
Nevertheless, a loss of a protective sea ice barrier does leave the shelves vulnerable.
Given the sub-surface warming of the ocean and subsequent weakening of the shelves, perhaps even "normal" sea ice conditions over summer months may be something to be concerned about.
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Agree GW. Sea ice acts as an effective barrier for ice shelves against ocean processes - and hence also protects the ice sheets themselves.
I coined a term "coastal exposure index" that keeps track of the broad-scale sea ice barrier. You can see it plotted in real time here: http://www.cawcr.gov.au/staff/preid/seaice/gsfc_sh_coastal_exposure.html. It's mostly interesting in summer months. A higher the coastal exposure index means trouble!
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Fantastic, thanks for the link.
By odd I was referring to the fact that May saw the highest sea ice area on record, whereas during the SH Winter months the values have been close to or at the lowest on record a number of times.
No probs.
Yes, the growth in areal extent did slow quite quickly. But it's not an unusual event - not unusual enough to perhaps make it "odd", but we won't worry about semantics. The sea ice distribution (and seasonality) is responding to one of its main drivers - ENSO. A similar thing happened in 2008 as the Pacific went from being cool (La Nina) to neutral. Right through January to early May the net sea ice extent was at (for then) record levels but dropped over the next few months to be at below average in September. See the chart here: http://www.cawcr.gov.au/staff/preid/seaice/gsfc_sh_extent_anom_past.html.
What I find interesting is what might happen next, after this El Nino. There are at least two competing thoughts: sea ice extents will return to their well-above averages; or, we will see the end of the upward trends in sea ice extents.
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A very odd year, and possibly a very early maximum (around 5th September). Anyone know which year had the earliest maximum?
I don't know that it is all that odd. Interesting, but not odd.
Yes. 1994 had the earliest annual daily maximum (based on data since 1979) - on 31st August.
See colour coding at http://www.cawcr.gov.au/staff/preid/seaice/sea_ice_table_extent.html
Note that the 2015 data are based on the NASA Team near-real-time data and will be updated once their final data are available.
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Tasboy, I was directly replying to posts #1465 and #1466, as there was a quibble about data between GW and MIA, I thought to save them the bother and to allow a better discussion I would try and find some information - whether or not the emissions from Oz would affect Antarctic ice directly is another matter.
Cool.
Being from Oz myself – albeit one of the states that use less coal than most – I’m embarrassed by our poor environmental record. I was at a conference recently where research was presented that showed coal and uranium dust in Antarctic ice core samples (glacial ice, not sea ice).
I sat there and cringed!
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At this time of the year it's quite unusual for sea ice extent to swap from being above average to below average, based on historical data.
And yes, it certainly has a lot to do with the wind stewfox.
In general, in the Northern Hemisphere you would find:
Wind blows from the south = nice to be in a beer garden.
Wind blows from the north = nice to be beside a fire with a pint.
That wind has a lot to answer for!
Standing by for the chocolate cake
Some data on energy generation in Australia, in case anyone is interested.
I have no idea on the validity of the data, I just found it on the internet.
http://reneweconomy.com.au/nem-watchInteresting, but not really part of this discussion?
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12 August 2015 - first below average net sea ice extent (based on 1981-2010 climatology) since Dec 2012.
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"...and better still somehow caused by an obscure effect of warming elsewhere."
You guys are funny!
The link between Pacific SSTs and the regionality of sea ice extent is well known.
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In need we should be discussing the record ice levels in the Antarctica , the theory re wind seems to be a bit weak ??
"""Air circulation patterns were variable for the month. The Southern Annular Mode, a north-south movement of the westerly wind belt that circles Antarctica, was in a near neutral state for the month as a whole"".
While SAM was close to neutral during May 2015 it has been continually positive since October 2014, and set a new positive record during those months (Feb 2015).
Today's sea-ice extent is just a snapshot of sea ice that has retreated and advanced over the previous few months. So it's not very accurate to say that "because the winds are low today then the sea ice should be close to average or below average".
Your mistake is fairly typical of someone who wants to make a quick judgement against science.
Besides, winds are just one variable (although an important one) that influences sea-ice variability and distribution.
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I assume that is going into the next IPCC report ?
Since you asked…
If it was scientifically interesting it probably could go in there. However statements like this are pretty useless – particularly when they are wrong - like the one I quoted.
Scientists aren’t so much interested in a useless statistic (such as this and many similar statistics on this list) but more interested in “why†or “what are the ramifications or the broader context of this statisticâ€. And they certainly aren’t interested in people’s “feelings†about long-term outlooks: eg “I have a feeling we will smash the global sea ice records this yearâ€. What hypothesis are you making and how can you prove or disprove you hypothesis? Seriously.
In my work environment you would need to provide a cake if that sort of prediction did not occur.
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Alarmingly, in 2015 the Antarctic sea-ice extent grew only 0.026 million square kms between the 4th and 5th April. That is the third lowest growth in extent ever recorded between those dates (behind 2009 and 1988).
See http://www.cawcr.gov.au/staff/preid/seaice/gsfc_sh_extent_anom.html.
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If you dont agree with the satellite data can you provide a link/evidence to the contrary.
As at 2nd April 6,669,078 that's another record for the time of year.
regards
Again, no it isn't. The satellite data are fine - as far as I know. You're just reading the graph wrong.
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Mean while record ice growth continues in 2015. Another daily record smashed
Um, no it isn't.
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Thanks for the link knocker. Nice discussions.
Here's some stats on the Antarctic sea ice anomaly so far this year:
- Daily sea ice area reached a new record anomaly on the 26th June 2014 (1.9 million sq kms) and there are a few current readings in the top 10 ever recorded.- Monthly area anomaly for June 2014 was second highest recorded (behind Dec 2007).- Daily extent anomalies have a while to go to catch those recorded in Dec 2007.- Monthly extent anomaly for April 2014 was the second highest on record (behind Jan 2008).
The cryosphere is interesting and does its own thing!
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Keith,
It really is an amazing event, yet again this year. The chances are that we will have the annual daily maximum sea ice extent broken three years in a row. And the large-scale processes associated with the SH sea ice this year are quite different, in some regards, to the previous two years.
It's fascinating – and why I love science.
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A brief article has been published online regarding the paradox of Antarctic sea ice extent:
Of particular interest is the fact that not only is extent at record levels but so is area. See:
- extent: http://www.cawcr.gov.au/staff/preid/seaice/sea_ice_table_extent.html
- area: http://www.cawcr.gov.au/staff/preid/seaice/sea_ice_table_area.html
There is a high correlation between yearly maximum sea ice extent and the extent values towards the end of June (see the Turner et al 2013 paper). High values of extent in the Weddell and Ross seas suggest that we are on target to break a new maximum sea ice extent for the Southern Hemisphere (based on data since 1979). Three record-breaking years in a row would be quite remarkable.
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It's interesting that some people get all excited because some part of the world is showing, in their opinion, opposite to what you expect under a global warming scenario.
Other people get excited because there are records being broken (in this case, Antarctic sea ice extent) and they would like to understand why and put it into context with what else they see.
Scientists are generally the people in the latter category. Any idea what the first category is?
There are a number of publications out there that go at least part way to explaining why Antarctic sea ice is expanding rather than shrinking, and why climate models are not able to sufficiently capture all the cryospheric processes that make Antarctica quite unique. People within this forum have pointed to a few of them. If you don't believe these publications then publish your own findings.
If you are going to make comments on scientific matters then at least try to read some scientific papers. Otherwise your ignorance is showing just a little.
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Nice papers! Thanks for the heads-up.
Links to both papers here:
- Joughin et al (Thwaites Glacier Basin): http://www.sciencemag.org/content/early/2014/05/12/science.1249055
- Rignot et al (Pine Island, Thwaites, Smith and Kohler glaciers): http://onlinelibrary.wiley.com/doi/10.1002/2014GL060140/abstract
Now, I wonder what link these might have to the records we're seeing in sea ice extent???
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7.376 sq km of ice
4th May 1980
10.561sq km of ice
5th May 2014
That s 6 times the area of France of new ice
http://www.cawcr.gov.au/staff/preid/seaice/sea_ice_table_extent.html
Global sea ice well above average
http://arctic.atmos.uiuc.edu/cryosphere/iphone/images/iphone.anomaly.global.png
Why 4th of May 1980? Why not 4th May 1979 (which was 9.502)?
But I agree, the record Antarctic sea ice extent at the moment is quite remarkable (in comparison to the relative short history of records).
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Wrong sea ice extent continues to break records highest sea ice extent for April since records began in 1979 http://nsidc.org/data/seaice_index/index.html
Yes, I agree. But that's not what I said, and that's not what you said. You might need to go back and re-read what you wrote.
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An interesting article has just been published on the importance of ice drainage from the Wilkes Basin (Ice plug prevents irreversible discharge from East Antarctica):
- http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2226.html
It's an interesting area for sea ice.
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Antarctic Ice Discussion
in Climate Change
Posted
It's nice to have you back Stew. I was missing you!
I don't know that I would call it (2015 Antarctic sea ice extent pattern) natural variability - perhaps it might be best described as a sudden response (it was quite a sudden slowdown in growth) to lower latitude forcings. But then again, that is part of natural variability...