Is Lake Superior Warming from the Top Down, or the Bottom Up?

This morning on CNN's website, I was reading an article on how Lake Superior is warming at an unusually fast rate.

NOAA has buoys on Superior that measure temperature, etc...I'm wondering though, are they like ARGO buoys in that they periodically descend and take readings at various layers, or do they only measure temperature at or near the surface...

"It's a remarkably rapid rate of change," Jay Austin, an assistant professor with the university's Large Lakes Observatory and Department of Physics, told the Star Tribune newspaper. Austin co-authored the study with geology professor Steve Colman.

The study is based on data collected by National Oceanic and Atmospheric Administration buoys on the lake and on 102 years' worth of daily temperature readings at a hydroelectric plant near Sault Ste. Marie, Michigan.

Source


I would think it would be somewhat remiss if these measurements were only taken at or near the surface...perhaps even more disturbing if it were found to be warming from the bottom up.

Any thoughts, or does anyone know??




AB1


Edited for Source

[edit on 6-4-2007 by alphabetaone]

I'd imagine it would be from the surface down, otherwise the buoys wouldn't pick up such dramatic changes as the water bottom all the way to the top would have to heat up for a change to be noticed.

But I could be wrong, it could be form the bottom up, which would indicate a magma vent on the lakebed or maybe a volcano. I don't think there's anything to worry about though, it's probably just global warming.

I think it is top to down, however with Lake Superior being so large I'm not sure if the lake "turns over" in the winter.

Well,

Yes this is precisely why I'm questioning it...the water at the surface would certainly show a change dramatically if all of the water below it were acting as a heat sink for the basin heating up...we really only have indication that the surface temperature is changing...

This is why I question the veracity of the results, while the air temperature above it has only reflected a 2.7 degree change in the same time period..

I wasnt thinking a magma vent necessarily, more I was thinking magma movement relocating hotspots to different areas


AB1

I think the warming is due to the surface air, not any geothermal activity. The article says that the water temp has raised 4.5 F and the air 2.7 F in that same time. Take out the fact that the lake is not freezing over anymore, the sun can now radiate on the surface of the water for 365 days a year.

[edit on 6-4-2007 by testrat]