On Thermal Expansion &Thermal Contraction - 22

Worldwide Tide Gauge Station Records

I. Updates

The PSMSL recently updated their down-loadable datasets (both monthly and annual datasets were offered), so I updated my SQL database to include those new tide gauge station records.

Fig. 1a

At the same time I adjusted the date bench-mark for the volume of the oceans to 2010 from 2000, and calibrated my relevant software modules to:

mean ocean depth: 3682.2 m

area: 361.841 x 10⁶ km²

volume: 1.332370930 x 10⁹ km³

The values are based on this paper: “The Volume of Earth's Ocean” (Oceanography, vol. 23, no. 2, 2010, pp. 112–114; PDF version).

Fig. 1b

I also ran across a definition of "thermal expansion", a term we see in sea level related text around the Internet:

"The 'thermosteric component of sea level change' represents the change of sea level due to warming or cooling of a column of sea water.

Warming of a sea water column results in higher sea level
and
cooling of a sea water column results in lower sea level."

(Definition of Thermosteric, Page 3, PDF). That was refreshing because we very rarely come across the mention of "oh by the way, when that warmed water cools it shrinks").

We have discussed that in this series a time or two (On Thermal Expansion & Thermal Contraction, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21).

II. Dredd Blog Content

I also ran across a bit of information which I have not really concerned myself with to tell you the truth:

"Authors have typically achieved higher levels of education than the average reading level and tend to write at the same reading level as other authors in their niche. So where does that leave the actual reader?

According to many reports (including the U.S. National Center for Education Statistics’ 1992 Adult Literacy survey), the average reading level is the 7th or 8th grade. Combine that with reports of increasingly low-attention spans of Internet users who require even milder language and you’re looking at a reading level of the 6th or 7th grade."

(EzineArticles Asks: What Reading Level Should You Target?, cf. What Grade Level Are You Writing For?).

I just write it and Dredd Blog readers read it.

I have full confidence that if regular readers (who are quite savvy) want clarification on any issue, they know how to get it (including "what the heck did you mean by that Dredd?").

II. Using The Updates

What is important in the context of thermal expansion/contraction (thermosteric volume change) is the original volume of the ocean at the beginning of the calculation sequence.

In this context, that date is 1880.

I conformed all the data (GISS, PSMSL, and WOD) to the year 1880 as the beginning date.

Since PSMSL and GISS have in situ measurements for that year, but WOD does not, I had to calculate the values, then project them into the past.

I discussed that previously (The World According To Anomalies - 2).

That exercise must be applied to generate the ocean mass-volume in 1880 as well.

To do that I first isolated the mass-volume value described in the paper linked-to in Section I. above (1.332370930 x 10⁹ km³), together with the year the mass-volume value was calculated (2010).

Next, I isolated the global mean sea level in that year, as measured by "the PSMSL golden 23 tide gauge stations."

With those values in hand it was easy to calculate backwards from 2010.

If the mean sea level fell or rose in any year I calculated the percentage of change in the PSMSL sea level, then adjusted the ocean mass-volume up or down based on the sea level change percent (5% drop in sea level = 5% drop in ocean mass-volume; 7% increase in sea level = 7% increase in mass-volume).

I proceeded until I (the software module) reached the year 1880, at which time I saved the value and used it for TEOS thermal expansion calculations going forward (Golden 23 Zones Meet TEOS-10).

The same technique is used to calculate historical ocean temperatures back to 1880, except GISS temperatures are used as the guide instead of PSMSL values.

Instead, I use the percent of GISS temperature value changes, then apply 93% of that GISS change to the WOD values.

The WOD values for CTD and PFL datasets are robust beginning circa 1967, so I start with the GISS surface temperature changes, and use 93% of that change.

That is because the current thinking is that about 93% of the heat from global warming ends up in the oceans.

III. Graphs Generated From The Updates

There isn't much change in the graphs generated after implementing the updates.

You can compare Fig. 1a and Fig. 1b with graphs generated prior to these changes (see The World According To Anomalies - 2, at Fig. 2 and Fig. 3).

However, there is a lot of difference between these recent thermal expansion/contraction (thermosteric) graphs and older ones, when I first wrestled with learning to use TEOS-10 and earlier formulas.

IV. Conclusion

I have a handle on it now, at least as reasonable a handle as the established scientific community has.

So, relax and don't expect changes in the way that is calculated, or in the results (unless readers point out an error in that process).

PS. Don't forget the ghost water (The Ghost-Water Constant, 2, 3, 4, 5, 6, 7, 8, 9).

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