Saturday, September 14, 2019

In Search Of Ocean Heat - 7

Fig. 1 Pelagic Depths
I. Background

It is, compared to the ocean depths, quite easy to find the heat in the atmosphere, the heat on land, and heat at the surface of the ocean.

However, that is not the case within the largest realm on Earth, the Pelagic Zone  (Fig. 1).

In this Dredd Blog series it has been pointed out that ocean heat is difficult to follow as it radiates into the unexplored places of the oceans (In Search Of Ocean Heat23456).

Other planets have been scientifically studied more than most of these pelagic realms:
"Where do we start? I suggest by making the ocean visible. Although nothing lives there, Mars, the Moon and Venus are better mapped (at about 100m x 100m resolution) than the seafloor, which is home to many of the 90% of a possible two million species in the ocean yet to be described—and along with them valuable novel marine genetic resources. It is often said that you cannot manage what you cannot measure, but equally the case is that you do not measure what you do not value."
(Newsweek, emphasis added). This is misguided and the result of mismanagement, most likely instigated by corporate propaganda and greed (New Continent Found - Garbage Gyre II) which all too often control scientific research efforts (A Falsified Oil-Qaeda Hypothesis Spreads).

Fig. 2 Conservative Temperature (CT)
Fig. 3 Ocean Heat Content (hO)
II. The Arctic Example

It is easy to follow the impact of global warming in the Arctic.

As it turns out, it is warming more than some other regions:
"Chelsea Wegner was shocked when she landed in Anchorage, Alaska, in July, on her way to a research cruise in the Bering Sea. Smoke from wildfires across the state had darkened the skies, and Anchorage was in the midst of a heatwave that saw temperatures soar past 32 °C [soar past 90°F] for the first time in recorded history.

Wegner, a marine biologist at the University of Maryland in Solomons, also knew that the unusual warmth had melted away nearly all of the sea ice in the Bering Sea. 'It was a really surreal moment,' she says.

Later, while sailing aboard a Canadian icebreaker off the coast of Alaska, Wegner watched walruses swimming in open water — without the ice floes they normally use as a platform to rest, give birth and nurse their young during the Arctic summer."
(Arctic revolution). A lot of the sea animals are, like humans, dying of heat further south ... "not making it" (ABC, Reuters, CNN).

III. How The Ocean Heat Gets "Lost"

The two graphs above (Fig. 2, Fig. 3) detail the trail of Conservative Temperature (CT) and Potential Enthalpy (hO), otherwise known as Ocean Heat Content and/or Ocean Heat Flux.

Ocean Heat Content is not lost to Dredd Blog software because the best thermodynamic tools for oceanographic research are used (Thermodynamic Equation Of Seawater - 2010, TEOS-10, cf. What every oceanographer needs to know about TEOS-10).

One of the scientists who worked to bring the new standard forth and to replace the old IOS-80 standard has carefully pointed out the problem with current software models:
"The quest in this work is to derive a variable that is conservative, independent of adiabatic changes in pressure, and whose conservation equation is the oceanic version of the first law of thermodynamics. That is, we seek a variable whose advection and diffusion can be interpreted as the advection and diffusion of ‘heat.’ In other words, we seek to answer the question, ‘what is heat’ in the ocean?
The variable that is currently used for this purpose in ocean models is potential temperature referenced to the sea surface, θ, but it does not accurately represent the conservation of heat because of (i) the variation of specific heat with salinity and (ii) the dependence of the total differential of enthalpy on variations of salinity.
For example, an increase in pressure of 107 Pa (1000 dbar), without exchange of heat or salt, causes a change in enthalpy that is equivalent to about 2.5ЊC. We show in this paper that in contrast to enthalpy, potential enthalpy does have the desired properties to embody the meaning of the first law.
Present treatment of oceanic heat fluxes is clearly inconsistent. Ocean models treat potential temperature as a conservative variable and calculate the heat flux across oceanic sections using a constant value of heat capacity. By contrast, heat flux through sections of observed data is often calculated using a variable specific heat multiplying the flux of potential temperature per unit area (Bryan 1962; Macdonald et al. 1994; Saunders 1995; Bacon and Fofonoff 1996). Here it is shown that the theoretical justification of this second approach is flawed on three counts. While the errors involved are small, it is clearly less than satisfactory to have conflicting practices in the observational and modeling parts of physical oceanography, particularly as an accurate and convenient solution can be found.
it is perfectly valid to talk of potential enthalpy, h0as the 'heat content' ...”
(In Search Of Ocean Heat). As with "what is the best time to solve global warming" the time to use TEOS-10 is way overdue (The TIME Has Come Today).

IV. Today's Graphs

The two graphs in today's post (Fig. 2, Fig. 3) show that ocean heat is radiating all the way down to the deepest ocean depths.

The Hadopelagic is the deepest, but it is now on average globally, warmer than the Abyssopelagic layer above it (since circa 1952).

In the world of oceanography concerning the thermocline, it is said that "The temperature of the deep ocean drops gradually with depth (Wikipedia)," but in the world of thermodynamics this is not axiomatic, because hot flows to cold (The Ghost Photons, 2, 3).

Ocean heat is radiating to the cooler waters of the deeps, and has been warming them (contrary to pre-global warming textbooks).

V. Closing Comments

The ocean heat content is not lost to TEOS-10, it is hard at work melting the tidewater glaciers that are flowing from the great ice sheets of Greenland and Antarctica.

They are melting below the water line at an accelerating rate of 6 to 8 fold (Science Daily, PNAS, cf. video below).

The next post in this series is here, the previous post in this series is here.


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