On The More Robust Sea Level Computation Techniques - 10

Fig. 1a

Fig. 1b

Fig. 1c

Fig. 1d

Fig. 1e

In a previous post in another series (The World According To Measurements - 17), I cited to a fairly recent paper that discussed a portion of the World Ocean Database (WOD).

That paper discussed the WOD records concerning the Arctic Ocean area  (WOD Arctic, PDF).

In today's post I want to caution professional and amateur researchers alike about the hazards of that form of specialization as it relates to comprehensive conclusions.

To start the show while emphasizing that point, let's look at thermosteric sea level change (a.k.a. thermal expansion / contraction) in the four graphs (Fig. 1a - Fig. 1d) of the four quadrants of the world ocean (NE, NW, SE, SW).

Then let's look at the mean average of those four (Fig. 1e).

The graphs at Fig. 1a - Fig. 1e were each made using the same TEOS-10 library functions to calculate results from in situ measurements stored in the WOD.

Those measurements were processed to produce Conservative Temperature (CT), Absolute Salinity (SA), and Pressure (P).

This computation took place at each one of 33 WOD depth levels (if they contained measurements).

The boundaries of the depth levels are: 0m, 10m, 20m, 30m, 50m, 75m, 100m, 125m, 150m, 200m, 250m, 300m, 400m, 500m, 600m, 700m, 800m, 900m, 1000m, 1100m, 1200m, 1300m, 1400m, 1500m, 1750m, 2000m, 2500m, 3000m, 3500m, 4000m, 4500m, 5000m, and 5500m plus.

Those levels (horizontal slices) contain the volume or quantity of seawater, which is also an essential element of the calculations.

In other words, to calculate volume change caused by temperature change one has to know both the amount of volume at issue as well as the amount of temperature change.

Fig. 2a

Fig. 2b

As you can see, some of those levels / volumes are 10m in height (e.g. 0-10m, 20-30m), some are 20m in height (e.g. 30-50m), and so on.

The resulting graphs at Fig. 1a - Fig. 1d are quite different from one another even though the exact same process generated them.

At the end of the process, the four quadrants were added together and averaged to form the final graph at Fig. 1e.

We can see that it would not be accurate to say that any one of the five graphs represent the whole story, because they actually show that the ocean varies quite a bit from location to location.

That is true even in mean average cases, because the CT, SA, and P vary with depth, as shown in the graphs at Fig. 2a and Fig. 2b.

Fig. 3a

Fig. 3b

Fig. 3c

Fig. 3d

Fig. 3e

In that case, neither the top layer CT nor the top layer SA are the greatest value of that type at that location.

The top level depth has the lowest SA but not the lowest CT.

At another location it may be reversed, so generalizations have to be done carefully.

For example, to say "sea level is rising" is not true everywhere, because there are many locations around the globe where sea level is falling (see e.g. The Gravity of Sea Level Change, 2, 3, 4, NASA Busts The Ghost).

The most critical thing as far as I am concerned is the granularity of the measurements applied to the particular research being done at any given time.

The graphs at Fig. 3b - Fig. 3e are generated from the 30-50m slice of the ocean in the four quadrants.

The average of those quadrants is shown in Fig. 3a.

Here again, over generalization is risky, but we can say that the CT and the thermal expansion have the same general pattern in all situations graphed in this case.

Fig. 4

It would be risky, however, to say that the pattern shown at that depth level holds true in all locations and depths at all times.

That is why we continue to measure, monitor, and graph data for readers.

The work is not done for us, it is done for you readers.

Nevertheless, it is enjoyable to be able to share the hard work done by the men and women who are gathering measurements for us.

Take care, and keep alert, because there is more data down there (see Fig. 4 for an example of more depth information to come).

The previous post in this series is here.

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"I want to fly like an eagle, to the sea ..."

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The World According To Measurements - 17

Fig. 1 Water Volume

Regular readers will remember that I recently indicated that I was perusing the TEOS-10 software library for some helpful confirmation routines.

The ones I found during that searched and analyzed (gsw_specvol, and gsw_rho) did the trick.

I can now use them to confirm the formula, which regular readers will remember, that I have used to calculate thermosteric sea level changes (V1 = V0 * (1 + B * DT).

The TEOS-10 software library routines calculate density and volume as they increase and/or decrease.

The graphic at Fig. 1 depicts an axiom: as density increases volume decreases (and vice versa).

That is explained to some degree by the statement: "density is the number of molecules / atoms in a space, while volume is how far apart those molecules / atoms are from one another."

So, we have to know the parameters of the "space" and we have to know how much mass is in that space.

Anyway, after updating my WOD data recently, I wanted to provide a link to a paper that covers a small portion of the World Ocean Database (WOD Arctic, PDF).

Fig. 2

Fig.3

Fig.4

Fig.5

Fig.6

Fig.7

Fig. 8 WOD zone quadrant view

It covers the WOD quite well, indicating how valuable that data is.

Since the area is a critical part of the world climate system, it is worth considering for a number of reasons.

I am fortunate enough to have all CTD and PFL WOD data, so I know that the WOD is incredible.

With the new analysis, the notion that thermal expansion is "the major cause of sea level rise" is falsified, while "the ice sheets are melting" is confirmed as the major cause of sea level rise.

On to the graphs.

The graph at Fig. 2 is the PSMSL sea level change record for the tide gauge stations that give a general concept of sea level change (see the video here).

The graph at Fig. 3 applies TEOS-10 functions to all WOD Zones.

The graph at Fig. 4 applies TEOS-10 functions to the NE Quadrant of WOD Zones.

The graph at Fig. 5 applies TEOS-10 functions to the NW Quadrant of WOD Zones.

The graph at Fig. 6 applies TEOS-10 functions to the SE Quadrant of WOD Zones.

And finally,  the graph at Fig. 7 applies TEOS-10 functions to the SW Quadrant of WOD Zones.

Notice that the specific volume is opposite to the density graph.

As one increases the other decreases accordingly.

Volume increase indicates that thermal expansion could be taking place, while density increase indicates that thermal contraction could be taking place.

The Conservative Temperature and Absolute Salinity graphs show that they have a part in the equation as to the expansion and contraction of each ocean quadrant.

The graphic at Fig. 8 outlines the four quadrants (NE, NW, SE, and SW).

Note that the 4 quadrants are separated according to the zero degree latitude and longitude lines, and the 180 degree longitude line.

Blue circles with "NE", "NW", "SE", and "SW" in them mark the four quadrants (the two narrow slices on the right-hand side of the graphic are part of the two eastern quadrants).

What I am working on now is using these functions to confirm the validity of a formula:

"These TEOS-10 functions can help keep a check and balance on the formula I use (V1 = V0 * (1 + B * DT) to calculate thermal expansion and contraction."

(The World According To Measurements - 16). I have a preliminary routine that multiples the Revised Local Reference (RLR) constant by the TEOS-10 specific volume value (see graphs for the specific volume values).

That comes very close to the thermal expansion / contraction pattern, so I am on the trail (cf. Proof of Concept - 10).

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