New Type of SLC Detection Model - 14

Fig. 1 SLF Group Mean SLC

Regular readers know that I rant from time to time about the misuse of "global mean average sea level."

I do so because it covers up some important information about the dynamics of sea level change (SLC) which the savvy observer needs to know in order to understand SLC in its non-intuitive aspects ("It does not work like water in a bath tub").

When using a module that does any "mean average" for a group of tide gauge station records, one must take care not to mix sea level fall (SLF) stations with sea level rise (SLR) stations.

Fig. 2 S:F Group Fingerprint

The module I just completed, and wrote about yesterday, can be used as an example of why global mean sea level, or even mean sea level in a smaller area, can be unproductive (New Type of SLC Detection Model - 13).

So, I used the model again today to generate two mean average sea level graphs for two groups that will illustrate the point.

Fig. 3 SLR Group Mean SLC

The graphs at Fig. 1 and Fig. 2 show the mean RLR and mean Dredd Blog SLC fingerprint module values for tide gauge stations that experience SLF near Glacier Bay: SITKA (#426), JUNEAU (#405), SKAGWAY (#495), YAKUTAT (#445), SEWARD (#266), CORDOVA (#566), and VALDEZ (#1353).

The other group of tide gauge stations from San Diego to Seattle experience SLR (Fig. 3 and Fig. 4).

Fig. 4 S:R Group Fingerprint

They are: SAN DIEGO (QUARANTINE STATION) (#158), LA JOLLA (SCRIPPS PIER) (#256), LOS ANGELES (#245), SANTA MONICA (MUNICIPAL PIER) (#377), SANTA BARBARA @ CALIFORNIA (#2126), PORT SAN LUIS (#508), MONTEREY (#1352), ALAMEDA (NAVAL AIR STATION) (#437), SAN FRANCISCO (#10), POINT REYES (#1394), ARENA COVE @ CALIFORNIA (#2125), N. SPIT @ HUMBOLDT BAY (#1639), CRESCENT CITY (#378), PORT ORFORD (#1640), CHARLESTON II (#1269), SOUTH BEACH (#1196), ASTORIA (TONGUE POINT) (#265), and SEATTLE (#127).

In terms of developing an understanding of the non-intuitive aspects of SLC, mixing the two types of  SLC tide gauge station records would do no one any good.

The opposing types of SLC (SLF and SLR) would be neutralized into a practically flat line by doing a global or local area mean average on them.

No one would then know sufficiently what was happening along the West Coast in terms of being aware of both types of SLC.

Which is what "global mean average sea level" does.

Anyway, the module takes latitude and longitude values from a user-made file, then gathers all tide gauge station data for the geographical area described in the file.

The model then aggregates all the data in order to present a year by year PSMSL RLR graph (Fig. 1, Fig. 3), as well as a Dredd Blog SLC fingerprint graph (Fig. 2, Fig. 4).

As with a single tide gauge station record, the model estimates the amount of SLC contributed by Antarctica, Greenland, and the glacial areas that impact the tide gauge or gauges in the geographical area specified by the latitudes and longitudes given it.

The previous post in this series is here.