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Author Topic: Determining ocean heat content and salinity  (Read 1562 times)

Ice Shieldz

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Determining ocean heat content and salinity
« on: July 29, 2017, 02:33:58 AM »
This topic explores the Ocean Heat Content and Salinity inquiry furthered by FishOutofWater's comment in What the boys are telling: http://forum.arctic-sea-ice.net/index.php/topic,327.msg122706.html#msg122706

???

Remember that the gulfstreams been deprived of its ability to evaporate water vapour and lose heat because of lack of Atlantic hurricanes last year, and being under a lid of fresher meltwater since off New York. Its probably hotter and fresher than we've ever recorded before and may be much more buoyant than anyone is expecting.

So we didn't get 80 cm rainfall in North Carolina from hurricane Matthew? The massive flooding was fake news and a figment of my imagination? My basement didn't fill with water?

You know, scientists actually measure temperature heat content and salinity in the north Atlantic.
https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/
Your wild assertions are not supported by evidence. There is a pool of cool fresh water south east of Greenland. There is a pool of cool fresh water in the Beaufort gyre. The Gulf Stream, however, is not getting fresher. The salinity of the Gulf Stream and subtropical Atlantic has increased.

Thanks Fish for the link on Global Ocean Heat Content and Salinity - bookmarked!

It would be nice if we had data on ocean heat content and salinity per latitudinal region (arctic, mid-latitudes and tropics). My assumption is that ocean heat content change is greater in higher latitudes than in lower latitudes. Is the change in the higher latitudes more focused on the upper ocean 0-700m?  Does El Nino/PDO provide a more efficient engine for pumping a greater ratio of heat into the deep tropical ocean?


From NOAA site linked above



Ocean heat uptake as a percentage of 1865-2015 change for CMIP5 model average. Large grey cross indicates that 50% of the total uptake occurred in 1997. Source: Gleckler et al. (2016). Illustration: Nature Climate Change

slow wing

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Re: Determining ocean heat content and salinity
« Reply #1 on: July 29, 2017, 03:40:54 AM »
Thanks Ice Shieldz, this is an important topic!

The Arctic sea ice is going to be blown around from now until the end of the melt season and how much melts out is going to be largely determined by how much heat in the water is available to it.

My impression is that we can't answer that question with any degree of accuracy because we don't have anywhere enough instrumentation in the water to tell us.

True or false?

If true then it's a travesty given the importance of the Arctic sea ice and given that deploying sufficient arrays of buoys should only cost in the ballpark of tens of millions of dollars - chickenfeed in today's global economy.


Is there a summary map somewhere showing locations of all the buoys in the Arctic basin with strings of temperature and salinity sensors?

Ice Shieldz

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Re: Determining ocean heat content and salinity
« Reply #2 on: July 29, 2017, 04:09:11 AM »
Yes would be great to have more buoys, data and assimilation/profiling of the data we do have.

In the mean time the following from the NOAA site linked above gives a view onto ocean heat content anomalies down to 700m in 5-year means starting from 1997 and ending in 2016.  Notice anything interesting here?

FishOutofWater

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Re: Determining ocean heat content and salinity
« Reply #3 on: July 29, 2017, 04:25:32 AM »
The "Atlantification" of the European sector of the Arctic involves a large increase in heat content. That's why I have been suggesting that the Atlantic side of the Arctic will have more melting than we might normally expect in the next 6 weeks.

We don't have enough instrumentation of the Arctic so the uncertainty in our models of the Arctic may be higher than in the north Atlantic, but we know damn well that heat has been increasing on the Atlantic side of the Arctic over the past 2 decades.

Note that the heat content increase around Antarctica is mostly in the intermediate waters from 200 to 700 meters depth. The top 100 meters is cold.

The northwards expansion of the north wall of the Gulf Stream involves huge amounts of heat because the water is warm hundreds of meters deep south of the wall. Likewise, the southwards movement of the subtropical front in the Indian ocean involves huge amounts of heat.

Jim Hunt

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Re: Determining ocean heat content and salinity
« Reply #4 on: July 29, 2017, 12:20:09 PM »
The primary OHC "instrumentation" consists of the fleet of Argo floats. The data they acquire is publicly available, but there aren't many in the Arctic!

Reality is merely an illusion, albeit a very persistent one - Albert Einstein

FishOutofWater

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Re: Determining ocean heat content and salinity
« Reply #5 on: July 29, 2017, 04:33:35 PM »
Argo floats are designed to pop up to the surface and report their data. Sea ice is not compatible with popping up to the surface. The Arctic is sampled by specially designed Arctic buoys and by expeditions by ships designed to deal with ice.

Once the ice is all gone oceanography will get a whole lot easier in the Arctic except for the crazy storms that will make today's Arctic seem placid.

Jim Hunt

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Re: Determining ocean heat content and salinity
« Reply #6 on: July 29, 2017, 05:41:12 PM »
There's also a few permanent(ish) moorings in the Arctic. The Fram Strait array being one example:

http://www.npolar.no/en/projects/fram-strait-arctic-outflow-observatory.html

Reality is merely an illusion, albeit a very persistent one - Albert Einstein

FishOutofWater

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Re: Determining ocean heat content and salinity
« Reply #7 on: July 30, 2017, 12:09:33 AM »
There are moorings on the Siberian side.

http://research.iarc.uaf.edu/NABOS2/technology.php