|Fig. 1 OHC and OHF|
This series is about a serious search being undertaken by ocean modelers, oceanographers, and researchers (In Search Of Ocean Heat, 2, 3, 4).
It is the sometimes frantic scientific search for ocean heat content (OHC) and ocean heat flux (OHF).
The search is more difficult than one would surmise at first blush, because a good many of those partaking in the search do not know what "ocean heat" is.
In some ways it is like the Supreme Court Justice who wrote in an opinion that he might not know how to describe a contract, but he knew one when he saw one.
Another one of the Supremes said the same thing about pornography in another case.
The general sense in terms of "ocean heat" is about the same or at least similar as those two examples: "I may not be able to describe what 'ocean heat' is, but I know it when I feel it" (see the theme song at the end of this post).
II. The Fairly Recent Discovery
Of What "Ocean Heat" Is
|Fig. 2a West Indian Ocean, area "A"|
|Fig. 2b East Indian Ocean, area "B"|
|Fig. 2c Ross Sea, area "C"|
|Fig. 2d Amundsen Sea, area "D"|
|Fig. 2e Bellingshausen Sea, area "E"|
|Fig. 2f Weddell Sea, area "F"|
A very experienced "heat scientist" who has no feelings one way or another about "heat" put it this way:
"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?(In Search Of Ocean Heat, quoting McDougall 2003). As a student of Josiah Willard Gibbs who "wrote the book" on OHC (The World According To Measurements - 12), McDougall et alia persuaded various and sundry world oceanography institutions to adapt a better thermodynamic perspective concerning what "ocean heat" is (TEOS Org).
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, h0, as the 'heat content'”
Too many in the general scientific community here and there seem to have mixed feelings about OHC, and so the first sentence on that site causes less than "in sync" reactions:
"This site is the official source of information about the Thermodynamic Equation Of Seawater - 2010 (TEOS-10), and the way in which it should be used."(ibid, emphasis added). For almost a decade now, conversations such as "how do you feel about Gibbs and TEOS-10 George ... I have mixed feelings about 'ocean heat' Bob" crop up and keep the current ocean models way too error prone concerning ocean heat.
This is exactly what McDougall went on to point out in the paper I referred to above:
"present ocean models contain typical errors of 0.1°C and maximum errors of 1.4°C in their temperature because of the neglect of the nonconservative production of potential temperature ... and potential temperature, rests on an incorrect theoretical foundation ..."(ibid, McDougall 2003). In concert with McDougall, a very recent paper pointed out some major "ocean heat" related developments in Antarctica.
That paper sorta points out that current ocean models might as well have been searching for ghosts:
"Such complexities in ice-ocean interaction are not currently represented in coupled ice sheet/ocean models"(The Ghost Photons - 3, quoting P. Milillo et al. 2019). That paper also points out the power that the "trained eye" has while using sophisticated satellite data.
"Ice shelf melt at A exceeds values used in numerical ice sheet/ocean models by factors of 2 to 3"
"preferential melt channels 1 to 2 km wide and newly formed cavities less than 100 m in height would require ocean models to operate at the subkilometer horizontal scale and sub–100 m vertical scale to replicate the melt processes that form the cavities, which is a challenge"
"the fact that peak melt rates in the main trunk are two to three times higher than those in models limits the ability of models to reproduce ice retreat at those locations"
"ocean-induced ice melt occurs over a 2.5-km-wide grounding zone, whereas numerical ice sheet models use fixed grounding lines, i.e., not affected by tidal mixing ... with zero melt applied at the grounding line"
"ice shelf melt rates may be lower along retrograde slopes than those along prograde slopes, another observation to explore in detail with ice-ocean models"
"We conclude that the cavity shape, including bed slope, bumps, and hollows in the bed, influences the access of ocean heat to the glacier and ocean-induced melt rates"
It beats using 1940 bi-planes, like TEOS-10 beats EOS-80.
III. Rich Research Area
Why waste rich research areas by using archaic software?
A typical contemporary paper these days does not mention TEOS-10, McDougall, thermodynamics, Gibbs, or what OHC actually is, but points out something like this:
"Recent estimates ... suggest that some 93% of the EEI [Earth’s Energy Imbalance] is going into the ocean, where it is manifested as changes in ocean heat content (OHC) ... However, attempts to track the flow of energy through the climate system and close Earth’s energy budget have run into discrepancies ... and substantial differences exist among estimates of the energy flows ..."(Insights into Earth’s Energy Imbalance from Multiple Sources). When a paper does not define what OHC is, does not mention the word "thermodynamics", does not consider that the ocean is composed of water molecules that harbor the "ocean heat", nor explain the quantum physics of photons of infrared radiation, I have to wonder why.
But I do not wonder why they are in error, nor am I surprised that those ocean models are error prone as McDougall 2003 and P. Milillo et al. 2019 point out in Section II above.
The official TEOS-10 (2010) which replaced the obsolete EOS-80 (1980) would help them if only they would stop ignoring it and start using it.
The WOD database, OMG database, SOCCOM database, WHI database would also help.
Listening to Gibbs, who is perhaps the most influential historical voice in ocean thermodynamics (encapsulated in TEOS-10) would also help:
"Albert Einstein called him 'the greatest mind in American history.' Gibbs’s studies of thermodynamics and discoveries in statistical mechanics paved the way for many of Einstein’s later discoveries."(American Physical Society). Especially since "encapsulated" means:
"TEOS-10 is based on a Gibbs function formulation from which all thermodynamic properties of seawater (density, enthalpy, entropy sound speed, etc.) can be derived in a thermodynamically consistent manner."(Thermodynamic Equation Of Seawater - 2010, emphasis added). Or they can continue to flop around like the scientists who forgot about gravity in the ocean realm, as pointed out by Woodward 1888; scientists who therefore could not figure out some major variations in sea level change (NASA Busts The Ghost).
After they get a grip on the quantum mechanical aspects of ocean thermodynamics, Antarctica will be a rich area for doing ocean heat research for them (Antarctica 2.0, 2, 3, 4, 5, 6 [& supplements A, B, C, D, E, F], 7; The Ghost Plumes - 4 [Appendices A, B, C, D, E, F]; Mysterious Zones of Antarctica, 2, 3, 4).
IV. Today's Graphs
Today's graphs (Fig. 2a - Fig. 2f) are all in this post (no appendices).
They have the same "A-F" categorization representing different areas of Antarctica as previous posts and appendices have had.
Each letter ("A" - "F") signifies an area around the continent of Antarctica as the posts listed in Section III did.
Recent Dredd Blog graphs have tended to show the proportionality of the TEOS-10 variables (e.g. Patterns: Conservative Temperature & Potential Enthalpy; Appendix One, Appendix Two, Appendix Three, Appendix-Four, Appendix-Five).
Today, the graphs show that even the proportionality of the seawater quantity necessary to melt one kg of tidewater glacier ice is in proportion to the Potential Enthalpy of the ambient tidewater.
As the ocean heat content per kg of seawater goes up, the quantity of seawater needed to melt a kg of glacier ice goes down.
Ocean heat content up = ocean ice quantity down (sounds reasonable eh?).
V. Closing Comments
Antarctica has hundreds of feet of potential sea level rise ... which is way, way more than enough to destroy current civilization as we know it (Civilization Is Now On Suicide Watch - 9).
It behooves us to use the existing reliable nomenclature about ocean heat so that we can avoid the self-inflicted legacy of the Titanic (Good Nomenclature: A Matter of Life and Death).
The next post in this series is here, the previous post in this series is here.
The ocean heat feelings of the moment ...