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Artful Dodger

Good job, Chris. To be clear, how much did your predictions change due to the effects of the storm?

Matthew

Hi all, First time post so - thank you all for such an informative blog! It is a higlight for me down here in Oz to catch up on all your overnight developments/comments each morning :) I do have a question (tongue in cheek). Why has Joe Bastardi (accuweather.com)not been invited to have a prediction in the SEARCH poll? :) after all could anyone forget his incredible predictions based on "my studies have shown".. http://www.youtube.com/watch?v=-G-ozEvSFVg

Espen Olsen

OH, Joe Bastardi is he still a live?

crandles

>"To be clear, how much did your predictions change due to the effects of the storm?"

Sticking to the July prediction technique the reduction from using 31 July area to 10 August data is 4.02 to 3.75. A fall of 0.27 m Km^2.

The straight line fall from weighted average area and extent fell from 4.41 to 4.04; a reduction of 0.37 M km^2.

The other calculation of the fall would be to use the weighted average of two different techniques that seem the best at the time. This gives a fall from 4.23 to 3.86; a reduction in the prediction of 0.37 M Km^2

So, take your pick of 0.27, 0.37 or 0.37 M Km^2 or do your own average or weighted average ;o)

crandles

So much for end of flash-back ie ice reappearing. CT area has increased again but only by a small amount:

2012.6083 -2.3179188 3.0995820 5.4175010
2012.6110 -2.2749753 3.1128488 5.3878241
2012.6136 -2.2251751 3.1131010 5.3382764

iceman

Chris, that's a useful calculation to estimate the total heating effect of the cyclone. For simplicity we could go for gross rather than net, which would require an estimate of amount of heat the storm expelled through the troposphere (among other things). First approximation would be:
reduction in area, ~ 0.33 M Km^2
x duration of ice loss, say through the end of the melt season
x change in albedo
x insolation at latitude (how to account for average cloud cover?)
Sound about right?

crandles

Iceman, those were estimates of extent minimums. So area would be less.

>"duration of ice loss, say through the end of the melt season"
hmm, not sure I am following. Are you trying to calculate extra heat absorbed as a result of extra water surface area?

Surface melt season has nearly ended - it is mainly bottom melt from now on and that is enhanced through mixing up the water.

iceman

Yes, heat absorbed by Earth's system as opposed to transferred from one part to another (e.g., heat from deeper water melting surface ice). So duration factors in the amount of time that extra open water remains from the cyclone until re-freeze (or Arctic sunset). Whether it's surface or bottom melting doesn't matter as long as there's less ice than there would have been absent the storm. The amount would be some fraction of your calculated result - after adjusting from extent to area - on Neven's assumption that some or all of the "flash melt" ice eventually would have gone anyway.

martinw

How do the Bremen numbers compare with NSIDC? To my squinting eyeball, it looks like they have already equalled the all-time low extent today in that data series:

http://www.iup.uni-bremen.de:8084/ssmis/extent_n_running_mean_previous.png

crandles

>Iceman "Yes, heat absorbed by Earth's system as opposed to transferred from one part to another"

But what if I think the mixing involved with the heat transferred from one part to another is crucial to understanding storms affect on future ice levels?

I see extra heat absorbtion this year as a fairly small term for melt this year and that heat will be lost in autumn/winter. The mixing that I see as potentially crucial could result in ocean remaining ice free for longer, giving off more heat down a longer water column than usual. This extra heat lost by the system may mean lower heat flux towards the surface when ice has formed during depths of winter and spring. This would allow thicker ice to form. This will then be slower to melt back next melt season.

So you are trying to measure what I see as a small bad effect while I am hoping there is much larger affect of the storm in the opposite direction causing thicker ice.

Peter Ellis

Exactly wrong. Arctic first-year ice is in general thicker than Antarctic first-year ice precisely because it forms within the shallow surface fresh-water layer.

Ice forming above a fully-mixed ocean is thinner and more saline, with the deep water acting as an almost inexhaustible heat source. For ice to form at all, it has to re-create its own seasonal halocline layer.

crandles

Thanks Peter.

So to see an increase in ice next year as a result of the storm, we would have to:

1. Have done a bit more mixing but not enough to mix in an inexhaustible heat source in the deep water? That seems quite possible to me.

2. The cooled surface waters sinking must not keep the salt mixed up or we would get thinner saltier ice that would melt quicker the next season. So, it is necessary for the salt to reseparate (through different rates of diffusion for heat and salt?).

3. Even if the salt does mainly separate and we only mix in an exhausible heat supply and this is exhausted, the surface waters are still likely to be a little saltier and this might slow the thickening and increase the speed of melting and we don't know whether this has more effect than the exhausing of the heat to a greater depth than usual.

Sounds like it might be quite a tall order for it to be a beneficial ice saving effect.

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