Wednesday, January 25, 2017

On Thermal Expansion & Thermal Contraction - 10

Fig. 1 World Ocean Database, Samoa Passage
In this series I have been challenging the, IMO, fallacy that thermal expansion of ocean water is the primary factor or even a major factor of sea level rise (On Thermal Expansion & Thermal Contraction, 2, 3, 4, 5, 6, 7, 8, 9).

Generally, conventional science, which has been applied going back a long time, indicates that "layering" in the oceans prevents the warming (from sunlight) upper level from generally reaching the deep ocean (Open Ocean Convection, Washington Edu).

Exceptions to the general rule that were discovered in the more distant past were called "deep ocean penetrating plumes."

Those downward plumes would mix the layers of water, causing various results (Transfer and Storage of Heat in the Oceans, Deep Ocean Penetrative Convection, the Physics Classroom).

As in most cases of scientific research, new discoveries have been made recently that have found some far more intense mechanisms for mixing ocean layers (mixing the ocean water's chemical contents as well as temperatures):
The chaos from skyscraper-tall waves breaking deep underwater has been captured for the first time, researchers say.

Fig. 2 Ocean Temperatures
Turbulence from these waves can generate thousands of times more mixing in the deep ocean than previously thought and, in turn, potentially require a critical rethinking of global models of climate and the oceans, the scientists who got a look at the phenomenon added.

Waves on the surface of the ocean generally can only grow up to a few dozen feet tall at most before collapsing, because water is so much heavier than air. However, underwater waves are made of deep, cold, dense water rising into layers of shallower, warmer, lighter water, and therefore, can reach titanic sizes.

"These waves can reach just huge sizes of about 200 meters [650 feet] — that's taller than a 60-story building," said researcher Matthew Alford, an oceanographer at the University of Washington, told LiveScience's OurAmazingPlanet.
These mammoth "internal waves" are thought to play a crucial role in mixing heat and chemicals across layers of the ocean that ordinarily never mingle — key factors that global models of the ocean and climate need to take into account.
(Breaking Underwater Waves Cause Mixing in Deep Ocean, Geophysical Research Letters, PDF). The graphic at Fig. 1 outlines (red square) the four WOD zones where the temperature measurements were taken at depths shown in  the graph @ Fig. 2.

In another Dredd Blog series I have been looking at temperatures at deep ocean depths from data recorded in the WOD database (link @ Fig. 1), so I am not surprised at the results shown in Fig. 2.

Thermal expansion becomes thermal contraction when the warm & cold waters mix to change or equalize temperatures (warm flows to cold, expansion diminishes, contraction increases until they, if possible, equalize in temperature according to the 2nd law of thermodynamics).

The "thermal expansion is the main factor in sea level rise in the 19th and 20th centuries" hypothesis is no longer credible,

Even when one or the other happens to be the bottom line measurement, thermal expansion and contraction are both minor players in global sea level change (ibid).

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