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Post by Ratty on Sept 16, 2014 22:55:59 GMT
When discussing the "depletion" of Antarctic land ice, one needs to keep a few things in mind. The entirety of evidence that the continent is losing ice mass comes from studies commissioned to support the CAGW movement. In fact the primary dataset used to justify the ice loss position is the GRACE data. What is interesting about the GRACE data is that the raw data shows a statistically significant INCREASE in ice mass in Antarctica. Let me repeat. Measurements demonstrate increasing Antarctic ice. The "Scientists" in charge of the study found this very inconvenient. Something had to be done. Grace was seeing an increase in mass where the computer models had predicted the opposite, not only did the observations indicate that the models were wrong, it conclusively demonstrated that the models had the sign wrong. Isostatic rebound to the rescue. Since everyone with a nose in the CAGW tough agrees that the models are correct something had to be done. The answer is to blame a phenomenon called glacial isostatic rebound on the... discrepancy. What the Grace "Scientists" did was they assumed that the ice was behaving as modeled, and that difference between the Grace measurements and model predictions were caused by the Antarctic continent rebounding from glaciation in the past. The Grace raw data was adjusted to support this premise. Evidence of this approach is everywhere. For example, Great Lakes ice levels in the U.S. absolutely destroyed previous records this year. Temperatures in the region ended up being recorded as above average. The most significant records in in the region were actually adjustments made to raw temperature readings. Those were at a record high. This boys and girls is how "Science" is done in the modern age. DontGetOutMuch, I would like to post something like that above on a "true believers" forum that hasn't booted me off (yet). Do you have something to which I can refer?
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Post by sigurdur on Sept 17, 2014 0:09:12 GMT
Ratty: The Grace data originally showed a decrease in Antarctic Land Ice Mass. But, there was an error in calibration which was discovered about 18 months ago. When that error was accounted for, all of a sudden Antarctica wasn't loosing ice mass, in fact the eastern area, the BIG area, was gaining ice mass. The only detectable ice mass loss, that is verifiable, is occurring in the Western Peninsula Area. And this loss is enhanced by volcanic activity.
I thought I had posted the paper that corrected the ice loss. Maybe I didn't, and I don't have time to dig through the thread to see. Try a bing search. Google is not a very reliable search engine when it comes to facts that dispute AGW.
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Post by icefisher on Sept 17, 2014 1:12:57 GMT
It seems natural to me to think that more sea ice would mean less precipitation would reach the inner land mass of Antarctica, and it would be expected based on that that the volume of ice on the Antarctic continent would decrease. I'm wondering what others have thought about that. I am coming around to believe that besides the well known convection loops in the atmosphere, we have at least one large convection loop in the ocean as well. As opposed to surface current patterns that are driven by trade winds in a horizontal circular pattern in both the Pacific and Atlantic, clockwise in the northern oceans and counterclockwise in the southern oceans; the convection loop current, better known as thermohaline circulation runs primarily pole to pole. I agree its possible the larger band of ice around the antarctic may reduce precipitation. Cooler water also reduces evaporation and increased upwelling of cold water (ostensibly due to ocean bottom cooling from more active thermohaline currents) will cool the waters around the antarctic and possibly induce a larger band of ice around the continent. What is missing from the above image is an upwelling area in the antarctic. It shows upwelling occuring near the equator after the deep current passes around the antarctic and heads north towards the equator again. But this ignores that antarctic has strong wind patterns conducive to upwelling (offshore winds) as we can see in this chart. Wind driven currents are on the surface and the cold currents that run from the poles to the equator are mostly surface wind driven currents. We do have upwelling along the Peruvian coast that is a dominant feature. It seems to come from the south also as NOAA has dipped the ENSO 1&2 zones south of the equator whereas the zones to the west all straddle the equator. All this seems supportable by recent SST anomaly charts where the water around the antarctic has been cold for a long time. Of course the big problem with this theory is that besides the missing heat not finding its way to the bottom of the ocean, its actually a case of the bottom of the ocean cooling. Might take a while for that to sink in. Another manifestation of this process besides the increase in ice around antarctic is the decrease in El Ninos, the weakening of El Ninos, the increase in number and strength of La Ninas.
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Post by flearider on Sept 17, 2014 8:52:26 GMT
there is only down welling round the Antarctic/arctic and there is no heat at the bottom of the ocean there may be some mid level but this would be forced upward .. basic heat in water rises and as it cools it drops . with a larger Antarctic your going to get stronger polar currents this propels the cold water thermohaline further and stronger .. again we seen this last yr .and we will see it stronger this yr if you take your second to last pic and place it over the sst .you can see the cold waiting gathering force(ocean current) as the melt starts to get under way this influx of very cold water will push it's way across the equator(thermohaline) .. as you say there are 2 forces at work the thermohaline circulation the main one and the secondary ocean currents
I see the real danger is when the thermohaline is so strong that it disrupts or changes the ocean currents as we will see over the next few yrs no ocean currents means no heat circulation which for those in the higher part of the northern hemisphere means a very short growing season ..
to see you must look but looking does not mean you will see .. but what do I know I'm a chef ..
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Post by Ratty on Sept 17, 2014 10:12:36 GMT
[ Snip ] to see you must look but looking does not mean you will see .. but what do I know I'm a chef .. What? You're not a climate scientist? Oh no !!!!
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Post by icefisher on Sept 17, 2014 10:59:56 GMT
there is only down welling round the Antarctic/arctic and there is no heat at the bottom of the ocean there may be some mid level but this would be forced upward .. basic heat in water rises and as it cools it drops . Downwelling likely only occurs in the winter when the air is much colder than the water. In the summer the air is warmer than water below the thermocline. Upwelling of deep cool water will occur any time there are offshore winds and deep water is near the shore. Thermocline drive currents are so slight they are not going to affect wind driven currents much except via changing the temperature of the surface waters.
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Post by nautonnier on Sept 17, 2014 11:56:14 GMT
Thermocline drive currents are so slight they are not going to affect wind driven currents much except via changing the temperature of the surface waters. I am not sure this is necessarily true. The thermohaline currents have huge momentum once they are moving it will take a lot of continuous strong counteracting wind to have any impact and that will likely only be on the surface expression of the main sea current. However, if both act together the effect of the thermohaline current with wind in the same sense will be considerably magnified. It is interesting to note that most of the work on the thermohaline and other deep water currents was done in and around the 2nd World War. Since that time there has been little research. Although the cable laying companies have come across fast flowing currents that are enough to drag away their cables. As someone wrote recently about the loss of Malaysian Airways 370, we know less about the deep oceans and sea bed than we do about the surface of Mars.
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Post by flearider on Sept 17, 2014 12:02:25 GMT
down welling cannot only occur in the winter .. the top surface of heat thick at the equator 1000m or so flows toward the poles as it does it loses heat thus making it less deep 100m or so after the heat is given up at or close to the poles the water sinks if this did not happen yr round then there would not be a constant thermohaline which there is .. chilled waters have increased densities, and thus tend to sink As sea water freezes, salt is forced out of the ice in a process called "brine exclusion". The excluded salt increases the salinity of the cold water immediately below the ice, making it denser still
can you show me where you read that "Thermocline drive currents are so slight they are not going to affect wind driven currents"
as far as I've read wind changes as do the lesser currents but the thermohaline current has been around for 12,000 years or more only stopping partially for the Younger Dryas
btw the thermohaline is a subsurface(warm) and bottom(cold) current so effects of wind would not make much of a difference
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Post by douglavers on Sept 17, 2014 13:36:31 GMT
Icefisher you said:
I don't think the deep oceans can get any cooler. Barring salinity/density effects, the maximum density of water is at 3 degC [probably a little lower in sea-water [?]].
I believe that all the world's oceans below about 1000m are at this temperature.
If the water is cooled further it will tend to rise towards the surface.
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Post by flearider on Sept 17, 2014 15:14:56 GMT
hmm 0 to -2 degrees C or 32 degrees F but the enormous pressure at the ocean floor prevents it from freezing this is at the poles .. but normally 1.5-4 deg c but then again there have been cold water jets at depth at 0 deg c cold water jets fast moving currents in the deep ocean not a lot is know about them ..
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Post by icefisher on Sept 17, 2014 16:31:51 GMT
Saying thermohaline currents are so slight is no doubt an over reach so I retract that characterization. Lets put it another way. Thermohaline currents at the bottom of the ocean are so slow they have never been measured and are merely postulated to exist. Warm surface currents associated with the thermohaline circulation are strong and measurable such as the Gulf Stream but its not possible to determine what portion of the current is in fact associated with thermohaline circulation and what is associated with feeding the currents that circle the oceans in both hemispheres and circles the Antarctica via wind forcing.
Ocean bottom thermohaline currents beyond the reach of the wind might be slow because of spreading like you see when you pour cold or heavier dye slowly in a still barrel of water, it sinks very rapidly to the bottom spreads across the bottom and then begins to broadly mix upwards in a rather chaotic fashion.
We don't have a good handle on the average temperature or salinity of the ocean bottoms due to a lack of sampling. Seawater density is a complex matter with the salt generally overriding temperature change bringing a concept of a halocline for the Arctic where freshwater melt of seaice sits ontop of the surface. The brines that are squeezed out of freezing seawater at about -2C is going to sink and it will mix with water below to sink further as it both increases salinity and lowers temperature of the water compared to the water surrounding it.
At a minimum I would suggest the loss of multiyear ice into a pattern of 1st year ice melting and refreezing, you are going to increase this process. We have seen how big ice losses lead to a bigger freeze the following winter.
I read one study but have no idea of where to find it again that suggested that super cooled water from being exposed to very cool winds will sink, so those -30C storms in the arctic when over unfrozen seas may increase downwelling without actually freezing the water (sensible heat polynyas). Latent heat polynyas may do both cooling water so it sinks and freezing water to add to that with brines from the conversion of water into a crystaline slush that slides downwind as portions of it sink drawing warm water up into the polynya as a vertical counter current making for a conveyor belt of water and brines sinking to the bottom of the ocean.
I would say its likely false that the ocean bottom is as cool as it can get. That seems contrary to the fact the larger ocean is exclusively exposed to warming forcing.
The ocean bottom has warming forcing all around it. The only cooling forcing is the water and brine that is cold enough to sink. Fingers of ice reaching the bottom from frozen brines sinking have been observed in the polar regions but this is probably fragile, temporary, and confined to shallow areas where the ocean surface freezes and probably related to the unusual formations that super cooling of water can create.
The only way to keep the bottom cold is via this active conveyor belt like thermohaline system. The envelope the ocean bottom sits in is warmth from the earth's core below and the warmth of water above. As the thermohaline system speeds up (say from large seasonal ice retreats and the subsequent more robust than normal refreeze) the ocean bottom should be cooling. And conversely when you have a lot of multi-year ice you have smaller areas refreezing so the ocean bottoms warm. I doubt there are any hard limits especially if the ocean froze solid there would be no hard limit.
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dresi
Level 3 Rank
Posts: 120
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Post by dresi on Sept 19, 2014 14:45:26 GMT
And it just keeps growing...
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Post by cuttydyer on Sept 19, 2014 16:06:19 GMT
Impressive gain; it's looking pretty chilly down South:
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Post by flearider on Sept 19, 2014 19:05:47 GMT
cutty take a look at the gulf stream .. to me it's slowing or being stopped by that lrg cold spot .. but I still believe it's to do with the cold coming from Antarctic .. but as we can only guess as icefisher has said we don't know to much about the ocean bottom or the cold Thermohaline.. but I have read about cold water jets moving very fast .. i'll guess these are more or less made up of fresher water(melted ice) allowing them to move faster ..
but I'm sure over the next 10 yrs we will find out ...
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Post by throttleup on Sept 19, 2014 19:57:29 GMT
dresi, If that Antarctic ice graph was a global temperature anomaly they'd say "we're all gonna die!"
Funny how they make great hubbub over one but ignore others...
(or claim that the ice "hockey stick" is caused by global warming)
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