Sunday, February 17, 2019

Countries With Sea Level Change - 2

Fig. 1 Greenland SLC "fingerprints"
I. Some Background

In the first post of this series readers noticed that some countries have sea level fall (SLF) while others have sea level rise (SLR).

That aspect of sea level change (SLC) upsets the time-worn dissertations of teachers who argue that the oceans are like a bathtub, in that, when water is added to the oceans they rise evenly like a bathtub's water level does.

Thus, under the auspices and guidance of those who use "the bathtub model" to explain SLC we are conditioned to the notion of global mean sea level (GMSL) numerology.

That the ocean is not like a bathtub, when it comes to sea level change, is surprising to their students in the sense of being nonintuitive, so I want to review that aspect of SLC a bit more in this post.

The physics of SLC are covered in other Dredd Blog series posts (e.g. The Ghost-Water Constant, 2, 3, 4, 5, 6, 7, 8, 9; The Gravity of Sea Level Change, 2, 3, 4; NASA Busts The Ghost) and links within them.

There are videos in some of those posts which feature Dr. Mitrovica, a scientist who has authored and co-authored various peer-reviewed papers on the subject over the span of many years.

II. Updated Country List

Tide Gauge Data Appendices (Graphs)
Countries: A - C A - C
Countries: D - G D - G
Countries: H - L H  -L
Countries: M - O M - O
Countries: P - T P - T
Countries: U - Y U - Y

The "countries list" in today's post contains more information about SLC influences, and the history of SLC, than the first post did.

When an inadequate number of years or other reason for not using the data exists, zeros will be used (but you can still view the PSMSL station records).

The appendices, however, are links to the original graphs from the first post in this series.

III. Distances

A tide gauge's distance from ice sheets is an important factor in what it will record, as is the rotation of the Earth, which can be easily surmised by taking a look at Fig. 1.
Fig. 2 Antarctica SLC "fingerprints"

In that graphic, Greenland's highest SLR impact takes place as far away from Greenland as the coastline of Antarctica.

But near Greenland there is only SLF impact (the opposite of SLR).

Comparing the graph at Fig. 1 with Antarctica (in the A-C list in today's post) makes this clear (some Antarctica tide gauges out on the peninsula, to the north of the coast, register SLR).

Thus, the Antarctica section contains this info:
"Distances from stations to:

Glacier Bay: 18307.7 km
Greenland: 16389 km
Svalbard: 16289.9 km
Patagonia: 5602.82 km
Antarctica: 2437.53 km

Sea Levels: 1st year 1957: 7011 RLR; last year 2016: 7062 RLR
SLC Analysis: Greenland is the predominant factor for 51 mm of SLR."
(Countries A-C). Notice that it says "Greenland is the predominant factor for 51 mm of SLR".

Notice again that Greenland's impact on SLR is greatest from the area around the southern tip of South America on down to the coastline of Antarctica (about as far away as one can get from Greenland).

The take home from these observations is that tide gauges very close to an ice sheet or ice field generally record SLF measurements (Fig. 2 shows the impact of SLC by Antarctica).

But when tide gauges are at a distance beyond "the gravitational hinge point" from an ice sheet or ice field, those tide gauges generally register SLR (e.g. Proof of Concept, 2, 3, 4, 5, 6, 7, 8, 9).

The gravitational hinge-point distance is key to whether tide gauges record SLR or SLF (e.g. The Evolution and Migration of Sea Level Hinge Points, 2).

IV. Different Strokes For Different Countries

The larger a country is the more likely it is that it will have tide gauge stations in areas where both SLF and SLR will be recorded.

Fig. 3 Greenland, Antarctica, Svalbard
Glacier Bay, & Patagonia SLC "fingerprints"
But, when only the average of the tide gauge station data in a particular country is disclosed, the SLC variation will be hidden.

So, in the country lists contained in today's post (Section II above) the tide gauge stations in each country are listed individually.

So, you can look up any such situations by clicking on the links to the specific tide gauge station you are interested in.

When the analysis at the end of each country's list indicates "SLF" you can look at the Dredd Blog graphs and the PSMSL links to check out why the tide gauge records show both SLF and SLR in the same country.

V. Closing Comments

As nations choose what to do in response to global warming induced SLC, they can choose to treat the cause (the cause is burning fossil fuels) or they can choose to treat the effect, such as the country's coastal perimeter changes caused by sea level changes there.

Treating the cause is simpler in concept because it only involves one factor: diminishing the use of fossil fuels.

Treating the effects is a more complicated endeavor in the sense that SLF presents one set of difficulties, in terms of sea ports, while SLR presents an opposite set of difficulties for sea ports (The Extinction of Robust Sea Ports, 2, 3, 4, 5, 6, 7, 8, 9; The Extinction of Charleston, The Extinction of Philadelphia, The Extinction of Washington, D.C., The Extinction of Boston, The Extinction of Miami, The Extinction of Manzanillo, The Extinction of Houston, The Extinction of Providence, The Extinction of Chesapeake Bay Islands).

Each country will have its own set of problems and solutions when they choose only to react to the effects (what fossil fuel use does to them).

But there is no bathtub model to follow (Fig. 3 shows the impact when all ice sheets and ice fields melt at equal volume rates).

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

No comments:

Post a Comment