|Fig. 1 @ over 1,000m (3,281 ft) deep|
There aren't even any PSMSL tide gauge stations there.
I finally was able to use the data for all zones combined.
So the graphs (Fig. 1 - Fig. 4) are old in the sense that they only go up to a decade ago, or less.
The big take away is that the sub-surface ocean water, during the times covered, gets above freezing.
The glaciologists I quote here on Dredd Blog indicate that the sub-surface ice will melt when the water temperature touching it is at or near 0 deg. C, (32 deg. F).
|Fig. 2 0m to 100m (328 ft)|
|Fig. 3 100m (328 ft) to 500m (1,640 ft)|
That data will have to be the ARGO and AMA data (ARGO Southern Ocean, Antarctic Ocean, AMA same).
|Fig. 4 500m (1,640 ft) to 1000m (3,281 ft)|
So, I am looking at that data again, although I do not like the "netcdf" data format they use.
Mainly because last time I checked, the library tools for extracting it were kept too close to their vests (perhaps they have a commercial streak in them).
Anyway, I am checking out the status of those sources again, because it has been a year or so since I took a look at ARGO.
The main problem, however, is that the ARGO robotic buoys are quite far away from the coast (Buoy/Float Map).
The closest ARGO float to the ice shelf seems to be the 1901251 Argo Profiling Float operated by Britain.
|Fig. 5 (Zones bq,br,bm,bn,bo,bq)|
|Fig. 6 (Zones bq,br,bm,bn,bo,bq)|
So, I took another look at the same GISS database I have been using.
I limited the inquiry to ocean temperatures above 0 deg. C (32 deg. F).
Any water temperature above 0 deg. C (32 deg. F) will tend to cause ice shelves and ice sheets to melt when and where that water contacts the ice.
I made two graphs to help visualize what has been going on down there under the Southern Ocean (a.k.a. Antarctic Ocean).
The graph @ Fig. 5 shows ocean temperatures from 0C (32 F) to 2.4C (36.32 F) at depths from 0m (surface) to 800m (2,625 ft) deep.
Note that the warmest water is at about the 400m (1,300 ft) depth (Fig. 5).
The graph @ Fig. 6 shows the high water temperature, at all depths, for each year from 1964 to 2006.
What these graphs show, then, is that water warm enough to melt subsurface ice has been around and under the surface of the Antarctic ocean for a long time.
To fill in the gap from 2006 to the most recent events, one can read some scientific papers published on the subject.
Papers which indicate that warmer water at about the 400m subsurface mark (as in Fig. 5) is still melting ice sheets and ice shelves in Antarctica:
"Warm modified Circumpolar Deep Water, which has been linked to glacier retreat in West Antarctica, has been observed in summer and winter on the nearby continental shelf beneath 400 to 500 m of cool Antarctic Surface Water" [in E. Antarctica too].(Nature). Thus, we can conclude that the beat goes on (Why Sea Level Rise May Be The Greatest Threat To Civilization - 3).
The next post in this series is here, the previous post in this series is here.