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TerryM

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1000 on: April 06, 2017, 07:05:21 AM »
If the break even day always occurs at polar equinox, does this mean that it always requires 24 hours of sunshine, at whatever angle, to achieve? This is not intuitive, at least to me.


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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1001 on: April 06, 2017, 07:55:03 AM »
No, the break even day is not the equinox.

The vernal equinox has passed but I very much doubt that break even has been reached for a clear sky over the North Pole.

Break even - presumably defined as when the surface temperature holds steady - requires the outgoing energy to balance the incoming energy.

The plot below from NASA, though intended for a slightly different purpose and displaying numerical values that wouldn't be appropriate at the North Pole, shows the contributions.

Outgoing from surface:
longwave thermal radiation from surface (will dominate at the moment at North Pole)
sunlight reflected from surface (EDIT: this isn't part of the thermal energy balance)
thermals
evapotranspiration


Incoming from atmosphere:
downgoing longwave thermal radiation from atmosphere (will dominate at the moment at North Pole)
incident sunlight absorbed


The values and relative sizes of these terms will depend on surface temperature, atmospheric temperature profile, surface emissivity/reflectance (which depends on wavelength and is very different for ice than for liquid water), atmospheric moisture content and the elevation of the sun above the horizon.

So there's no fixed date for break even.

In general, break even at the North Pole or in the Arctic, with a clear sky, can only occur when the sun is well above the horizon - so that will be well past the vernal equinox.
« Last Edit: April 06, 2017, 11:21:05 AM by slow wing »

be cause

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1002 on: April 06, 2017, 02:01:58 PM »
today's UK lunchtime radio 4 forecast .. 'there's lots of stuff happening in the upper atmosphere' .. explaining high sun burn potential ..
  anyone got a more complete explanation ?
cheers .. bc
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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1003 on: April 06, 2017, 02:15:48 PM »
Maybe they are talking about that lack of ozone over Altlantic/Great Britain?
https://ozonewatch.gsfc.nasa.gov/Scripts/big_image.php?date=2017-04&hem=N&source=IOMI_PAURA_V8F_MGEOS5FP&section=MAPS

Just read a german article here about last year https://www.welt.de/wissenschaft/article152064885/Extremes-Ozonloch-ueber-der-Nordhalbkugel-befuerchtet.html

it tells about extreme low pressure area in Feb. 2016 with extreme low temperatures in the upper athmosphere that would lead to stratosphere clouds, that cause a ozone destroying reaction in the upper latitudes. Assume this winter had not been better... :o

« Last Edit: April 06, 2017, 02:43:31 PM by nicibiene »
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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1004 on: April 06, 2017, 04:33:04 PM »
For the pole the break-even day for radiation is of course the equinox since the orbit, but this is still a good question considering lower latitudes.

Well maybe it's s day or two before equinox for the pole since the light scattering and bending properties of atmosphere but for blackbody. I guess the Moon could serve as a nuce example.

I don't think that's the case. At equinox the sun is right at the horizon... I  find it odd that it would be exactly the same as the net radiation water at 0C radiates out.

Anyway I did a little googling (finding:http://www.applet-magic.com/insolation.htm) and it suggests that the incoming radiation is still 0 at the equinox... which I think is perhaps aggressive rounding, but it's all together too big of an angle to be much energy, anyway. 

So it's not that. :)

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1005 on: April 06, 2017, 05:25:47 PM »
For the pole the break-even day for radiation is of course the equinox since the orbit, but this is still a good question considering lower latitudes.

Well maybe it's s day or two before equinox for the pole since the light scattering and bending properties of atmosphere but for blackbody. I guess the Moon could serve as a nuce example.

I don't think that's the case. At equinox the sun is right at the horizon... I  find it odd that it would be exactly the same as the net radiation water at 0C radiates out.

Anyway I did a little googling (finding:http://www.applet-magic.com/insolation.htm) and it suggests that the incoming radiation is still 0 at the equinox... which I think is perhaps aggressive rounding, but it's all together too big of an angle to be much energy, anyway. 

So it's not that. :)

Yep, water is no blackbody. Nor is ice. The atmosphere makes this a tricky question.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1006 on: April 06, 2017, 06:01:55 PM »

Yep, water is no blackbody. Nor is ice. The atmosphere makes this a tricky question.


Make simplyfying assumptions as necessary. I was trying to throw weather out, where possible.  Pick your favorite weather, average the weather, whatever makes the calculation easy.

I'm looking for a ballpark figure; when the sun is enough on its own to keep the water open. I really don't have a sense of it.

You can always cheat and use observations; we have pretty good observations of temperature of outbound (as measured by satellite), a pretty good sense of albedo (I did suggest open water), and a little internet digging will give you the incident (I know they exist, though I was't having much luck finding a good one).  It's true that observations are prone to all sorts of variables (most notably clouds) but it should be a decent ballpark.

By early May, the insolation for north pole crosses the incident of the equator so certainly it's somewhere sooner than that. At equinox it's 0W incident, so it's later than that. It gives about a 50 day range; I'd say probably it's between April 1 and May 10 just based on that information.

Jim Williams

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1007 on: April 06, 2017, 06:43:58 PM »

Yep, water is no blackbody. Nor is ice. The atmosphere makes this a tricky question.


Make simplyfying assumptions as necessary. I was trying to throw weather out, where possible.  Pick your favorite weather, average the weather, whatever makes the calculation easy.

I'm looking for a ballpark figure; when the sun is enough on its own to keep the water open. I really don't have a sense of it.

You can always cheat and use observations; we have pretty good observations of temperature of outbound (as measured by satellite), a pretty good sense of albedo (I did suggest open water), and a little internet digging will give you the incident (I know they exist, though I was't having much luck finding a good one).  It's true that observations are prone to all sorts of variables (most notably clouds) but it should be a decent ballpark.

By early May, the insolation for north pole crosses the incident of the equator so certainly it's somewhere sooner than that. At equinox it's 0W incident, so it's later than that. It gives about a 50 day range; I'd say probably it's between April 1 and May 10 just based on that information.

Since I too would love to see some sort of table providing the basic information, let me try to explain what is wanted.  Here in New England in about Mid-March after a snow storm even on cold days the Sun is "hot" enough to melt the snow during the day.  You can have all sorts of other things going on, but by basic seasonality at some date for a given latitude the Sun shines bright enough that the dirt (ice) can't keep things from melting.  A storm can, but not the surface.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1008 on: April 06, 2017, 08:20:25 PM »

Yep, water is no blackbody. Nor is ice. The atmosphere makes this a tricky question.


Make simplyfying assumptions as necessary. I was trying to throw weather out, where possible.  Pick your favorite weather, average the weather, whatever makes the calculation easy.

I'm looking for a ballpark figure; when the sun is enough on its own to keep the water open. I really don't have a sense of it.

You can always cheat and use observations; we have pretty good observations of temperature of outbound (as measured by satellite), a pretty good sense of albedo (I did suggest open water), and a little internet digging will give you the incident (I know they exist, though I was't having much luck finding a good one).  It's true that observations are prone to all sorts of variables (most notably clouds) but it should be a decent ballpark.

By early May, the insolation for north pole crosses the incident of the equator so certainly it's somewhere sooner than that. At equinox it's 0W incident, so it's later than that. It gives about a 50 day range; I'd say probably it's between April 1 and May 10 just based on that information.
I'd say April 20 and May 10 for peripheral seas (within the Arctic proper) based on what we observed other years, that is, when new cracks do not refreeze anymore.
We have seen refreezing in the middle of the CAB happen much later, even after generalized surface melting. I guess when a crack is surrounded 360 by ice and a cold spell comes, the refreezing is easier...
Really tricky stuff

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1009 on: April 07, 2017, 12:43:35 AM »
Make simplyfying assumptions as necessary.

Am I allowed to simplify it to 2 different problems.

One where Arctic sea ice extent starts shrinking instead of growing. This is the typical or trend date of maximum extent. Early March.

Second where ice volume starts shrinking rather than growing. This is trend date for PIOMAS volume max. Mid April.

If not either of these, what was the question again?

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1010 on: April 07, 2017, 02:57:36 AM »
Make simplyfying assumptions as necessary.

Am I allowed to simplify it to 2 different problems.

One where Arctic sea ice extent starts shrinking instead of growing. This is the typical or trend date of maximum extent. Early March.

Second where ice volume starts shrinking rather than growing. This is trend date for PIOMAS volume max. Mid April.

If not either of these, what was the question again?

Perfect measures to watch as they capture the entire system dynamics, sun, salinity and waves, warm moist air intrusions etc. Have SIE and volume maximums been occurring earlier in the Spring over time? Are SIE and volume minimums occurring later in the Fall?
« Last Edit: April 08, 2017, 05:52:47 PM by Shared Humanity »

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1011 on: April 07, 2017, 04:17:05 AM »



Based on incoming insolation and Outgoing Longwave Radiation (OLR), I'd say the equilibrium point is between the last week of March and mid-April depending upon which arctic latitude we want to look at.

Jim Williams

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1012 on: April 07, 2017, 02:18:07 PM »



Based on incoming insolation and Outgoing Longwave Radiation (OLR), I'd say the equilibrium point is between the last week of March and mid-April depending upon which arctic latitude we want to look at.

Interesting, and I think might be close to answering the real question.  If I assume the thermal conductivity of ice at 0C is the point at which irradiance would start to melt the surface of the ice, and if I am correct in interpreting the 2.20 in the table in the link below as the same as 220 in your graphs then it would give about the same result  as you have suggested for total OLR.

http://www.engineeringtoolbox.com/ice-thermal-properties-d_576.html

The difference being that I think real dates could be assigned (with enough thought) for when the Sun is hot enough to start melting the ice.

Am I at all close here?

ktonine

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1013 on: April 07, 2017, 04:39:35 PM »
Based on incoming insolation and Outgoing Longwave Radiation (OLR), I'd say the equilibrium point is between the last week of March and mid-April depending upon which arctic latitude we want to look at.
Interesting, and I think might be close to answering the real question.  If I assume the thermal conductivity of ice at 0C is the point at which irradiance would start to melt the surface of the ice, and if I am correct in interpreting the 2.20 in the table in the link below as the same as 220 in your graphs then it would give about the same result  as you have suggested for total OLR.

The difference being that I think real dates could be assigned (with enough thought) for when the Sun is hot enough to start melting the ice.

Am I at all close here?

I'm not sure what water/ice has to do with it.  If we did the same calculation at 30°N or at the equator we would come up with a different value for insolation, OLR, and the equilibrium date.  Water/ice will have nothing to do with the calculation.

The differences at the same latitude can be significant. Compare south-central Greenland to areas of the north Atlantic just a few degrees east.  Insolation is constant at the same latitude, but OLR varies by 35 W/m^2 or more.  This would lead to an equilibrium difference of a couple of weeks or more.

Jim Williams

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1014 on: April 07, 2017, 05:54:26 PM »
Based on incoming insolation and Outgoing Longwave Radiation (OLR), I'd say the equilibrium point is between the last week of March and mid-April depending upon which arctic latitude we want to look at.
Interesting, and I think might be close to answering the real question.  If I assume the thermal conductivity of ice at 0C is the point at which irradiance would start to melt the surface of the ice, and if I am correct in interpreting the 2.20 in the table in the link below as the same as 220 in your graphs then it would give about the same result  as you have suggested for total OLR.

The difference being that I think real dates could be assigned (with enough thought) for when the Sun is hot enough to start melting the ice.

Am I at all close here?

I'm not sure what water/ice has to do with it.  If we did the same calculation at 30°N or at the equator we would come up with a different value for insolation, OLR, and the equilibrium date.  Water/ice will have nothing to do with the calculation.

The differences at the same latitude can be significant. Compare south-central Greenland to areas of the north Atlantic just a few degrees east.  Insolation is constant at the same latitude, but OLR varies by 35 W/m^2 or more.  This would lead to an equilibrium difference of a couple of weeks or more.

The Fact that OLR varies is exactly what is wrong with it as a measure of the arrival of Spring at a given latitude.  The "emotional" Spring happens when the Sun is hot enough to start melting the ice.  It seems to me that the original question is basically "on what date can we expect Spring at a given latitude?"

I posit that Spring has arrived when the Sun is hot enough it can melt ice -- not when all the other stuff happens such that the ice actually melts; which can actually happen before Spring.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1015 on: April 08, 2017, 10:39:43 AM »
So a relatively simple question motivated by seeing some new ice form...

Do we know what day is breakeven for heat flux, counting only radiation, at various latitudes? Assume clear skies (though I'd be curious for cloudy too), and open water at 0C for albedo/blackbody purposes.

That is - if we only look at heat gained from the sun and heat lost via longwave to space (ignore atmospheric interaction, upwelling, currents, etc), what day of the solar year does this breakeven occur at various latitudes?

The original question seems to be asking when is the sunshine strong enough to balance OLR on open water (leads, etc.) without drawing energy from other sources. From the graphs it this thread I would put OLR at about 220w/m2 from cold water (but someone will have an accurate figure?), agreeing with late March to mid April. It would only be theoretical because in practice this would be later than ice would form (as the seawater would need to cool to about -10°C for ice to form) unless a lot of 'cold' was imported from somewhere else.
OTOH because of the high albedo of ice/snow there still would not be enough energy absorbed to actually melt anything and the surface is likely to remain below 00C  until the sunshine is considerably stronger (but OLR would also be lower and more variable). That makes for another interesting question?

seaicesailor

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1016 on: April 08, 2017, 11:20:46 AM »
So a relatively simple question motivated by seeing some new ice form...

Do we know what day is breakeven for heat flux, counting only radiation, at various latitudes? Assume clear skies (though I'd be curious for cloudy too), and open water at 0C for albedo/blackbody purposes.

That is - if we only look at heat gained from the sun and heat lost via longwave to space (ignore atmospheric interaction, upwelling, currents, etc), what day of the solar year does this breakeven occur at various latitudes?

The original question seems to be asking when is the sunshine strong enough to balance OLR on open water (leads, etc.) without drawing energy from other sources. From the graphs it this thread I would put OLR at about 220w/m2 from cold water (but someone will have an accurate figure?), agreeing with late March to mid April. It would only be theoretical because in practice this would be later than ice would form (as the seawater would need to cool to about -10°C for ice to form) unless a lot of 'cold' was imported from somewhere else.
OTOH because of the high albedo of ice/snow there still would not be enough energy absorbed to actually melt anything and the surface is likely to remain below 00C  until the sunshine is considerably stronger (but OLR would also be lower and more variable). That makes for another interesting question?
That "-10C for ice to form" is just a rule of thumb, or a simplified way to say that there are other heat sources, as for example water warmed up during summer in the upper layer of the ocean, that keep ocean water surface above freezing point for some time even when atm temps plunge well over zero, and as long as there is some stirring and mixing.
That is all for the freezing season start. As for the melting season start, something similar happens, there are additional effects that (most probably) delay the persistence of open water.
An important factor is the effect of  land masses. In fall, air advected from continents starts to have a cooling effect, whereas at some point of the Spring, air acvected from continents starts to have a warming effect. I believe the effect of transported heat this way is not totally accounted for in the OLR - incoming sw radiation balance approximation. That makes the problem very location-dependent. It also adds some inertia to the problem, (I think), since you need to have land snow cover meltout ongoing (or gone) in order to not receive spells of cold air advected from the continents, delaying the day of overall heat balance for some days.
By observing a few seasons as I said for me the 1st of May is when the bell rings for this particular problem, plus minus 10 days
« Last Edit: April 08, 2017, 11:35:43 AM by seaicesailor »

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1017 on: April 08, 2017, 11:29:03 AM »
P.S. I see on http://www.arctic.io/explorer/4Xa5A//4-N90-E0 that ice is still forming on Jakobshavn fjord (07/04/17) so radiation balance is not enough?! Open water is freezing all over the Arctic Ocean, the only melt seems to be at the southern fringes (Baffin Bay, Fram Strait, Bering Sea, Barents Sea). Cold still coming off the ice?

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1018 on: April 08, 2017, 11:43:05 AM »
P.S. I see on http://www.arctic.io/explorer/4Xa5A//4-N90-E0 that ice is still forming on Jakobshavn fjord (07/04/17) so radiation balance is not enough?! Open water is freezing all over the Arctic Ocean, the only melt seems to be at the southern fringes (Baffin Bay, Fram Strait, Bering Sea, Barents Sea). Cold still coming off the ice?
Nice viewer ...
See the widening opening in Beaufort sea. Alaska is still freaking cold. It might be that sun radiation is about to overcome olr but southerlies or easterlies there are really cold today. The opening will refreeze before May

Shared Humanity

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1019 on: April 08, 2017, 05:55:43 PM »
Whether it freezes or not, that image shows dramatically how fragile 1.5 meter thick ice is.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1020 on: April 08, 2017, 09:48:40 PM »
Whether it freezes or not, that image shows dramatically how fragile 1.5 meter thick ice is.
Right, already hundreds (or thousands) of floes of all range of sizes and the melting season yet not even started there.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1021 on: April 12, 2017, 07:37:40 AM »
Are these areas truly refreezing or what? As the days progress other floes break off and move over the thin ice in between the bigger floes. The way these move across, You have to ask is that really newly formed thin ice or actually water, as it appears that the smaller floes float across, or are these just sliding across thin slippery ice?
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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1022 on: April 12, 2017, 07:41:13 AM »
And the last three frames in slo-mo. I am really thinking this to be water at this point. I think the ice broke unevenly at angles and that the edge shows through the water. I know, I know. Yes, I got bored.
« Last Edit: April 12, 2017, 02:34:46 PM by Tigertown »
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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1023 on: April 12, 2017, 08:45:46 AM »
It's mostly the difference between the structural integrity of ice less than 10cm thick and ice over a meter thick, I think.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1024 on: April 12, 2017, 01:32:20 PM »
If it's hovering around -11 there will not be much impetus to the freezing, there's clearly some wind action so snow drift is a possibility, er, don't know, but it looks very thin.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1025 on: April 12, 2017, 02:41:10 PM »
I think the darker area is the broad side of the thicker ice, and you can briefly see the water line about halfway up, with the free-board above the line. Therefore, we are seeing water.
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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1026 on: April 12, 2017, 02:43:22 PM »
And the last three frames in slo-mo. I am really thinking this to be water at this point. I think the ice broke unevenly at angles and that the edge shows through the water. I know, I know. Yes, I got bored.


Take a look at the last frame and the 'new' fracture in the infill ice. when I look at Beaufort I see a lot of such fracturing which is distinct from the old 'angular' fracturing we used to see through 'crackopalypse' events.

Is this a visual confirmation of just how poor the ice is across Beaufort this year with the only 'normal' fracturing occurring in the last of the MY ice on its way to Fram?
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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1027 on: April 12, 2017, 02:54:47 PM »
Those cracks are top to bottom in the darker area. Watch it really close and you can tell the difference in the surface cracks and the sides.
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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1028 on: April 12, 2017, 06:45:58 PM »
No, this is absolutely typical of refreezing.  You can even see the increasing thickness of the ice in each lead as parallel stripes - as the lead pulls further open, new ice is constantly forming in the gap, and you see bands of 1-day, 2-day , 3-day ice, etc.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1029 on: April 12, 2017, 06:48:38 PM »
Of course we see open water (the darkest of the "rings" being formed around the separating floes) but it is proportionally very small area wrt grey bands of refrozen ice. Actually your animation TT spans like seven days and maybe only 1/50th of the area is open water. That means to me that water stays open in average three hours (or lets say a few hours) before closing

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1030 on: April 12, 2017, 06:49:46 PM »
I think the darker area is the broad side of the thicker ice, and you can briefly see the water line about halfway up, with the free-board above the line. Therefore, we are seeing water.

What? No. A single pixel from this satellite represents 250 metres.  You cannot see the freeboard of ice on this.  If you could, then we would not need to worry, as the ice would be at least 250 metres thick!

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1031 on: April 12, 2017, 07:12:03 PM »
Those cracks are top to bottom in the darker area. Watch it really close and you can tell the difference in the surface cracks and the sides.
The darker areas are areas of thin ice which have formed over less than 6days. That this ice breaks differently from  ice which has been growing to a thickness of maybe 2m since the beginning of winter is hardly surprising. I don't think there is multiyear ice in that area, very little movement in Beaufort this winter.
Compared to the large extent of the ice, even 2m is very thin and has no chance to withstand the forces of wind and currents. The thicker floes moving into an area of freshly frozen ice just piles this stuff up or pushes it under water forming ridges. You can see the "whitening" in front of the moving floes where this dynamic thickening occurs.

[url]/https://go.nasa.gov/2o6XhG3[url] adding links to where the images come from makes it easier for others to see what is discussed

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1032 on: April 12, 2017, 08:32:15 PM »
Those cracks are top to bottom in the darker area. Watch it really close and you can tell the difference in the surface cracks and the sides.
The darker areas are areas of thin ice which have formed over less than 6days. That this ice breaks differently from  ice which has been growing to a thickness of maybe 2m since the beginning of winter is hardly surprising. I don't think there is multiyear ice in that area, very little movement in Beaufort this winter.
Compared to the large extent of the ice, even 2m is very thin and has no chance to withstand the forces of wind and currents. The thicker floes moving into an area of freshly frozen ice just piles this stuff up or pushes it under water forming ridges. You can see the "whitening" in front of the moving floes where this dynamic thickening occurs.

[url]/https://go.nasa.gov/2o6XhG3[url] adding links to where the images come from makes it easier for others to see what is discussed
That was one possibility that had occurred to me. I see now that it was a mistake for me to dismiss it.

@Peter Ellis
I guess I overestimated the zoom. ;)  Thanks for straightening out.

Thanks to all.
"....and the appointed time came for God to bring to ruin those ruining the earth." Revelation 11:18.

Jim Williams

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1033 on: April 18, 2017, 04:59:33 PM »
I tried to formulate a question for Google seeking information on what we know about changes in bottom water temperature and salinity over the last few centuries and came up with nothing.

Anyone know the right question to ask?  I am specifically interested in what we currently know about when bottom water returns to the surface after becoming bottom water -- and how much heat it contains.

gerontocrat

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1034 on: April 18, 2017, 09:19:29 PM »
You asked Google and came back with zilch, nada, zero ?  I thought that meant Google had to give you a prize. Of  note is that it is becoming more apparent every day that it is the oceans that matter most - and of which we know the least.
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Bruce Steele

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1035 on: April 18, 2017, 09:49:44 PM »
Jim, You should read through the whole tread but here is one post from ASLR. Much of the thread has to do with Antacrtic bottom water formation and further info on the North Atlantic Bottom water processes are necessary for a full picture of bottom water. The Pacific doesn't have a northern hemispheric production site but the main site of bottom water return to surface waters occurred in the Eastern Equatorial Pacific. Residence times from creation to return are about a thousand years.

Re: Discussion of WAIS Collapse Main Period from 2060 to 2100
« Reply #47 on: July 12, 2013, 05:26:22 PM »
Quote
I am concerned that some readers are not familiar with the excellent work of Purkey and Johnson focused on AABW but also very important to the trends in warm CDW (see reply #9 in this trend, and in the first attached figure see the Weddell-Enderby temperature curve indicating warm water that could be contributing now to basal ice melting for FRIS).  The following reference and abstract cites their continuing valuable work in 2013:
 
Antarctic Bottom Water warming and freshening: Contributions to sea level rise, ocean freshwater budgets, and global heat gain
by: Sarah G. Purkey, and Gregory C. Johnson; Journal of Climate 2013 ; doi: http://dx.doi.org/10.1175/JCLI-D-12-00834.1

Abstract: "Freshening and warming of Antarctic Bottom Water (AABW) between the 1980s and 2000s are quantified, assessing the relative contributions of water-mass changes and isotherm heave. The analysis uses highly accurate, full-depth, ship-based, conductivity-temperature-depth measurements taken along repeated oceanographic sections around the Southern Ocean. Fresher varieties of AABW are present within the South Pacific and South Indian oceans in 2000s compared to the 1990s, with the strongest freshening in the newest waters adjacent to the Antarctic continental slope and rise indicating a recent shift in the salinity of AABW produced in this region. Bottom waters in the Weddell Sea exhibit significantly less water-mass freshening than those in the other two southern basins. However, a decrease in the volume of the coldest, deepest waters is observed throughout the entire Southern Ocean. This isotherm heave causes a salinification and warming on isobaths from the bottom up to the shallow potential temperature maximum. The water-mass freshening of AABW in the Indian and Pacific sectors is equivalent to a freshwater flux of 73 ±26 Gt yr-1, roughly half of the estimated recent mass loss of the West Antarctic Ice Sheet. Isotherm heave integrated below 2000 m and south of 30 °S equates to a net heat uptake of 34 ±3 TW of excess energy entering the deep ocean from deep volume loss of AABW and 0.37 ±0.15 mm yr-1 of sea level rise from associated thermal expansion."
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Jim Williams

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1036 on: April 18, 2017, 11:04:48 PM »
Jim, You should read through the whole tread but here is one post from ASLR. Much of the thread has to do with Antacrtic bottom water formation and further info on the North Atlantic Bottom

ASLR is talking about models and theory, not data.  While I think his take on theory and models is interesting, that is not what I am interested in...I want to know what data we have on the subject of the return of heat from the deep water to the surface -- if any.


sidd

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1037 on: April 19, 2017, 01:36:27 AM »
Re: "I want to know what data we have ..."

dear god did you even read Purkey and Johnson ? Thats a beautiful paper, and has links to the data. Even the abstract included in the post sez

" The analysis uses highly accurate, full-depth, ship-based, conductivity-temperature-depth measurements taken along repeated oceanographic sections around the Southern Ocean. "

At this point all i can say is "Can you read ?"

sidd

misfratz

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1038 on: April 21, 2017, 01:04:28 AM »
As there are some cuts to earth sciences in a country that relies it's science to be developed by immigrant scientists (well there are some natives too) the following stupid question might be in order. Could there be an instrument on the surface that could measure the ghg's in the atmospheric layers without relying to satellite observations for calibration?
It is possible that a type of lidar would be able to do that, though it might be easier to take direct observations with some sort of radiosonde, or aircraft.

Main reason I wanted to answer, though, is to point out that satellite observations have to be heavily calibrated by more direct observations, because putting scientific instruments into space is awful for accurate calibration of those instruments. So much effort is put into carefully calibrating the instruments and then it is shoved on top of a rocket and blasted into orbit, pretty much wrecking the calibration.

The main advantage that satellite observations have is that it is much easier to get complete spatial coverage, but you definitely need ground truth observations to calibrate the satellite observations with (and not vice versa).

sark

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1039 on: April 21, 2017, 01:16:20 AM »
Empirical evidence that CO2 is a greenhouse gas?

I've seen some talk about CO2 experiments a'la Eunice Foote / John Tyndall that invalidate the process they used.  I've also seen an explanation that spoke about quantum physics at the beginning of a youtube lecture (that I can't find anymore), and I was wondering if anyone could point me to research that describes the greenhouse effect empirically...

Is there a flaw with experiments that derive the greenhouse effect of co2 in a lab, in a cardboard box, in a test tube, etc?

I hate to have to add this, but there is no attempt to discredit the AGW consensus here.  I've been watching climate since ~1999 but IANAS and am curious about the physics
« Last Edit: April 21, 2017, 04:12:51 AM by sark »


seaicesailor

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1041 on: April 21, 2017, 07:44:11 PM »
Then Scientist American article explaining and debunking a lot of crap you find out there
https://www.scientificamerican.com/article/why-carbon-dioxide-is-greenhouse-gas/
And i like this simplistic kind of explanations:
https://scied.ucar.edu/carbon-dioxide-absorbs-and-re-emits-infrared-radiation
But if you dont believe it , you have tons of lab (and very accurate quantum dynamics models lately) results, and if you don't believe it, .... well you are free in your beliefs :-)

ktonine

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1042 on: April 21, 2017, 08:05:22 PM »
A great resource is Spencer Weart's The Discovery of Global Warming. The first chapter is: The Carbon Dioxide Greenhouse Effect

jai mitchell

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1043 on: April 21, 2017, 08:53:16 PM »
besides 200 years of study of the greenhouse effect properties of CO2, including the tuning of air to air missiles to the CO2 emission spectrum, the global warming impact of CO2 has been directly measured in 2 locations by LBNL.

http://newscenter.lbl.gov/2015/02/25/co2-greenhouse-effect-increase/
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sark

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1044 on: April 23, 2017, 06:51:30 PM »
Thank you all for responding to my question about the quantum states of co2.  Another burning question I've had for many months, which caused me to register to this forum... what is the salinity of ice sheet water?

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1045 on: April 24, 2017, 02:38:34 AM »
sark someone with some knowledge will soon answer, but please make sure you know what you are asking:
Ice sheet covers land, in Greenland and Antarctica, is made of snow compressed over 1000s of years, and is therefore fresh water. Sea ice is made of frozen salt water, and over time and given cold temps becomes more and more fresh through brine rejection. Which one did you mean?

TerryM

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1046 on: April 24, 2017, 04:18:39 AM »
sark someone with some knowledge will soon answer, but please make sure you know what you are asking:
Ice sheet covers land, in Greenland and Antarctica, is made of snow compressed over 1000s of years, and is therefore fresh water. Sea ice is made of frozen salt water, and over time and given cold temps becomes more and more fresh through brine rejection. Which one did you mean?
I'm not sure that, over time, the answers wouldn't be the same.
Glacial ice from Mendenhall Glacier was a favorite in San Francisco, back before the quake, to cool gentlemen's whiskey, as it didn't melt as rapidly (and dilute the liquor). It was the purity of the ice that slowed the melt.


Terry

sark

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1047 on: April 24, 2017, 08:02:53 AM »
I was wondering about μS/cm details of Greenland ice sheet water in particular.  I went on a Google hunt looking for records but don't even know what I'm looking for.

Peter Ellis

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1048 on: April 24, 2017, 09:54:29 AM »
Glacial ice from Mendenhall Glacier was a favorite in San Francisco, back before the quake, to cool gentlemen's whiskey, as it didn't melt as rapidly (and dilute the liquor). It was the purity of the ice that slowed the melt.
Possibly.  Or they may just not have been the first or the last rich people to buy stupid things for stupid regions. Remember, this is a world in which people will buy bottled water from f*cking Fiji.

ktonine

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1049 on: April 25, 2017, 12:10:07 AM »
Thank you all for responding to my question about the quantum states of co2.  Another burning question I've had for many months, which caused me to register to this forum... what is the salinity of ice sheet water?

As pointed out by oren, land ice should be essentially free of salt (other than what gets there via the atmosphere).  For gaseous composition wiki has some information.
Wikipedia - Ice core