Saturday, June 2, 2018

Let's Not Be Too Dense - 2

Fig. 1 Water is an uncommon liquid
Regular readers know how I learned where I should look to find the more obvious ocean waters in order to search for thermal expansion and contraction evidence.

It is somewhat like the serial bank robber who was finally nabbed, and was asked by the detective, "Righty, why do you persist in robbing banks?"

The previously Scot-free serial bank robber replied to the FBI agent, "Well copper, I did it for all of those years because that is where the money is."

So, to fit the metaphor, and to be worthy researchers, we would ask "where is the sea water that is being impacted by thermal expansion?"

And to be more precise, that place to search would be where the sea water is receiving most of the heat from the Sun during our era of increasing global warming.

The answer is the Southern Ocean:
"The vast Southern Ocean, which surrounds Antarctica, plays a starring role in the future of climate change. The global oceans together absorb over 90 percent of the excess heat in the climate system and roughly three-quarters of that heat uptake occurs in the Southern Ocean."
(Climate Central, emphasis added). The former "over 90 percent" is now calculated to be 93%.

Using 93% as the "over 90 percent", that final amount is 70% (93 * .75 = ~70%).

The graphic at Fig. 1 shows the strange nature of water in the sense that adding heat to either pure water or sea water does not ipso facto mean that the water will expand.

It could shrink, too.

It depends on the condition of the sea water at the time the heat is added or removed, (especially the in situ temperature).

The module I mentioned in a previous post (On Thermal Expansion & Thermal Contraction - 36)  generated the CSV files for producing the graphs at Fig. 2a - Fig. 2r below.

Today's graphs are about year to year changes in measured values.

Usually, graphs are based on measured values, not changes in measured values.

Some brief definitions:
CT changes: This value concerns the Conservative Temperature (CT) of the in situ location (year, latitude, longitude, depth level).

MDCT changes: These values concern the CT changes at which the Maximum Density (MDCT) takes place (Fig. 1).

Density Factor (DF) changes: This value represents the gap between CT and MDCT. When this gap is narrowing, thermal contraction is taking place. The degree of that thermal contraction depends on the size of the gap (in deg. C) between them. If they are equal, Maximum Denisty of that specific sea water has taken place.

Thermosteric Sea Level changes: These values concern the sea water volume changes due to sea water temperature, density, & salinity changes from year to year.

Typically, CT values must be equal to MDCT values for maximum density to have taken place. But, even when the CT is merely approaching the MDCT, i.e. the gap between them is narrowing, thermal contraction is taking place. The degree of that thermal contraction depends on the size of the gap (deg. C) between them. To the contrary, when that DF gap is increasing, thermal expansion is taking place. And of course, in the rare case that the CT is less than the MDCT, the opposite scenario takes place.
On a running total basis for these graphs, each value is calculated by subtracting the previous year value from the current year value.

All in all, the hypothesis depicted in the graphic at Fig. 1 is confirmed (density is a factor in thermal dynamics).

The previous post in this series is here.

Fig. 2a
Fig. 2b

Fig. 2c
Fig. 2d
Fig. 2e
Fig. 2f
Fig. 2g
Fig. 2h
Fig. 2i
Fig. 2j
Fig. 2k
Fig. 2l
Fig. 2m
Fig. 2n
Fig. 2o
Fig. 2p
Fig. 2q
Fig. 2r

1 comment:

  1. "Retreat at Thwaites Glacier ... currently the subject of greatest concern among Antarctic ice experts—has slightly increased in the last few years, from about 1,100 feet to nearly 1,400 feet per year."

    Tidewater glacier melt is the main source of sea level change (link).