"Joseph Gwinn" wrote in message
...
In article ,
"Ed Huntress" wrote:

"Joseph Gwinn" wrote in message
...
In article ,
"Ed Huntress" wrote:

"Joseph Gwinn" wrote in message
...
In article ,
"Ed Huntress" wrote:

[snip]

You're talking about one measurement path, a Great Circle, which
may
or
may
not cross numerous currents, the initiation site for El Nino, and
so
on.
From that you're trying to draw a conclusion about global warming.
You
don't
know if the pattern between here and NZ is pro-cyclical or
counter-cyclical
to the earth's temperature as a whole. You are talking about a
measurement
taken over a short span of years, while the data being looked at by
serious
scientists is data from decades at least, and hundreds of years in
some
cases.

Well, I don't have a dog in the debate from which this is taken, but
I
will add
that it is not impossible to disentangle all those things. What is
done
is the acoustic equivalent of computerized tomography.

Here is a random article dredged up by google:
http://jjap.ipap.jp/link?JJAP/40/5446/.

Joe Gwinn

Joe, I'm going to skip the article, because there are 2,000 or 3,000
that
I'd have to read first.

Not if the intent is to understand the method.

Hey, Joe, I got curious and took a look at it. What in the hell are you
talking about here? Of COURSE temperature differentials result in sound
velocity differentials. That wasn't the question. Nor are statistical
sampling methods part of the question.

Nor was it the point.


The question is, what is the effect of all of the variables upon ocean
temperature, current temperatures and paths, and their cyclical or
countercyclical relation to worldwide global warming? What's causing
warming
or cooling along that linear path, and how does it relate to the overall
effect?

As I said, this allows one to measure the changes. Explaining them is
quite
another matter.

Well, we know that there are methods to measure the changes in ocean
temperature. There is only one significant question here, which is what does
it really tell us about overall warming? Dan's original point was that if
the guy he knows who is doing this work tells him there is global warming,
he'll believe it. To which my response is, I can't see how.



The article doesn't touch upon that. What it DOES do is explain a method
for
measuring temperature with the velocity proxy. They've been able to do
that
for 100 years, by my guess. This is just a quick and simple method, as
the
article's title describes.

I don't think they knew of this method 100 years ago, but it doesn't
matter, as
the method is quite impractical without computers. Now it's easy.

Well, they probably knew about velocities of sound in water in relation to
the water's temperature. Maybe they could measure it in the lab. What Dan is
talking about is measuring it across oceans. It may well be possible to a
high degree of accuracy. And it very well may tell you all kinds of useful
things about the relationships of ocean temperatures in certain regions to
weather. It probably also will tell you about a *mean* temperature trend
along a specific Great Circle line.

But the time span is too short to address the kinds of temperature trends
that are significant to the questions about global warming, and, as we've
now discussed ad nauseum, it doesn't address whether temperatures along that
particular line are in direct, or inverse relation to trends at the largest
scale.

Ocean currents change their paths with changes in climate. We may be seeing
it now with the Gulf Stream; it's moved within our lifetimes, as any old
offshore fisherman can confirm. And that's only one of the variables.

--
Ed Huntress