Temperature vs. depth

[Robert Helling]

Hi,

yesterday, I had an hour of time and I played around with an idea that I would like to get some feedback on (I already showed it to my wife and she absolutely hated it).

The idea is not to show the temperature as a function of time as we currently do it but rather plot it against depth. I find it much less interesting what the temperature was 28 minutes into the dive but rather want to know what was the temperature at 12m of depth and in particular like to see the positions of thermoclines. So here is a mock up:




The way you are supposed to look at it is that depth is depth but the time axis for this plot becomes the temperature axis (currently the scale is chosen that minutes coincide with degrees centigrade).
What you are supposed to see is that above about 15m of depth the water constantly has about 12 degrees thanks to mixing by wind etc. Below that, there is a thermocline and then the temperature goes down continuously. Apparently, I measured slightly different temperatures on the way down and up but that is probably due to a time delay in the sensor to take up temperature readings.

Here is the same dive in the traditional view:

-





This I can imagine you bring up against this idea:

* You really like the old view (of course I would make this optional)
* This presentation is really confusing, the time axis is supposed to show time.
* It gets in the way of the depth profile
* This is not even a function of depth as there is more than one temperature per depth value

Please not that this so far is only a mock up. It would need to get a proper coordinate axis (maybe on top) as the 1minute = 1 degree thing is not god given and in particular does not work in imperial units. Rather than being an overlay on the depth profile it could also be moved to the left or the right of it so it shares the depth axis but gets its own x-axis for temperature (like the other plots sharing the time axis with the depth profile but having their own y-axes). The price for that would of course be horizontal space.

But before investing too much time into this I wanted to gauge if that would be wasted because everybody else hates it or whether it’s worth pursuing.

Best
Robert

PS: The code for the mockup is in my verticaltemperture branch on GitHub.


.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oO
Robert C. Helling Elite Master Course Theoretical and Mathematical Physics
Scientific Coordinator
Ludwig Maximilians Universitaet Muenchen, Dept. Physik
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[Dirk Hohndel]

Post by Robert Helling
yesterday, I had an hour of time and I played around with an idea that I would like to get some feedback on (I already showed it to my wife and she absolutely hated it).

I love your honesty here :-)

Post by Robert Helling
The way you are supposed to look at it is that depth is depth but the time axis for this plot becomes the temperature axis (currently the scale is chosen that minutes coincide with degrees centigrade).
What you are supposed to see is that above about 15m of depth the water constantly has about 12 degrees thanks to mixing by wind etc. Below that, there is a thermocline and then the temperature goes down continuously. Apparently, I measured slightly different temperatures on the way down and up but that is probably due to a time delay in the sensor to take up temperature readings.
-
* You really like the old view (of course I would make this optional)
* This presentation is really confusing, the time axis is supposed to show time.
* It gets in the way of the depth profile
* This is not even a function of depth as there is more than one temperature per depth value
Please not that this so far is only a mock up. It would need to get a proper coordinate axis (maybe on top) as the 1minute = 1 degree thing is not god given and in particular does not work in imperial units. Rather than being an overlay on the depth profile it could also be moved to the left or the right of it so it shares the depth axis but gets its own x-axis for temperature (like the other plots sharing the time axis with the depth profile but having their own y-axes). The price for that would of course be horizontal space.
But before investing too much time into this I wanted to gauge if that would be wasted because everybody else hates it or whether it’s worth pursuing.

I think you picked a poor dive to showcase why this is interesting. In your bathtub-profile, the interesting information is fairly easy to eye-ball even on the existing graph.
You need a Linus-style dive. Crazy depth changes all over the place - hey Linus, can you give him one of your wilder 3D dives? Cathedrals or something like that? I've seen some of these profiles and there the correlation of depth and temperature isn't obvious at all in the standard graph (of course cathedrals is by Lanai so there isn't much of a thermocline in the first place, so maybe that one isn't all that interesting, either).

My point is - I think this is worth more investigation.
An optional graph to the left of the main graph (the overlay seems odd). Easy to turn on and off with a button.
I'm curious to hear what others think, but this does seem quite interesting.
Oh, and I'd do it as a scatter plot...

my 2 cents

/D

[Jan Mulder]

Post by Dirk Hohndel

Post by Robert Helling
yesterday, I had an hour of time and I played around with an idea that
I would like to get some feedback on (I already showed it to my wife
and she absolutely hated it).

My point is - I think this is worth more investigation.
An optional graph to the left of the main graph (the overlay seems odd).
Easy to turn on and off with a button.
I'm curious to hear what others think, but this does seem quite interesting.
Oh, and I'd do it as a scatter plot...

I feel that, while an interesting idea, this will not be tremendously
useful. I see 2 main reasons for this. 1) Only fresh water dives show
relevant thermoclines, and dives at sea tend to have a very limited
temperature change over depth (over the typical range of diving depths).
And 2), more important, I think that a lot of DCs have a very poor
temperature sensor (as in slow responding). That is, as you correctly
said, already visible in the 1 mock up dive (and I believe that the used
OSTC has a very decent, as in quick responding, temperature sensor).

In cave diving, water temperatures are relatively constant, but when
there is a difference, the most interesting, is the place where that is,
so directly related to time, like we have now. So no added value there.

--jan

[Lutz Vieweg]

I feel that, while an interesting idea, this will not be tremendously useful. I see 2 main reasons
for this. 1) Only fresh water dives show relevant thermoclines, and dives at sea tend to have a very
limited temperature change over depth (over the typical range of diving depths).

I have experiences very pronounced thermoclines in the sea,
- in the gulf of Oman
- on many shores in Indonesia
- even at Isla del Cocos

And 2), more important, I think that a lot of DCs have a very poor temperature sensor (as in slow responding).

They are slow responding in air, but under water, it usually takes just a few seconds
for them to change.


But I've got a different suggestion for visualization: Instead of abusing the X-Axis
for something not time, just paint a background-color gradient (like from blue to purple or yellow)
instead of the current linear light-to-dark-blue background color gradient, to visualizes the
temperature at depth.

Regards,

Lutz Vieweg

[Linus Torvalds]

Post by Lutz Vieweg
They are slow responding in air, but under water, it usually takes just a few seconds
for them to change.

That's definitely not true.

I looked at my dive profiles, and I see things like "it took five
minutes for the temperature to stabilize".

This obviously depends on the dive computer and some will be much
better than others, but I really don't think the "temperature by
depth" can work in general. You're much better off looking at the time
progression, and just eye-balling how it matches with depth.

For example, looking at my dives in Bonaire, there was a clear
thermocline at around 105 ft on one dive, but almost all the other
dives were pretty much "constant water temperature", so I can clearly
look at just that dive.

And I had four dive computers with me on that dive:

- the Suunto EON Core tracks depth pretty closely, and with a delay
of only about one minute. The profile looks sane and the temperature
profile matches is well with a 0.1°C resolution, just delayed a bit.
For nice slow descent/ascent, the one-minute delay is probably not
even all that noticeable.

- the Garmin Descent Mk1 only gives you 1°C resolution, but like the
EON Core, it seems to be fairly quick to react (again, looking at the
profile, I'd say "roughly one minute" delay). But the 1C resolution
means that it's fairly noisy.

- The Aqualung i770R gives 1°F resolution,m but the delay looks like
it's about three minutes.

- The Shearwater Perdix AI similarly gives 1°F resolution with a
three-minute delay.

The reason I say that the delay can be up to five minutes is that I
look at the Shearwater profiles, and on the dives where water
termperature was pretty much constant, it quite commonly takes about
five minutes for the sensor to stabilize from the air temperature.

Looking around at other dive trips:

- Maui has almost no temperature gradients by recreational depths

- Okinawa had temperature gradients, but the biggest ones seem to be
only indirectly about depth. The shore dives show a big temperature
gradient in shallow waters, but it looks like it's less about
"shallow" and more about "close to shore".

- some of my dives show temperature fluctuations that seem to have
nothing to do with either surface or depth, and seem to be more about
currents etc

Basically, on the data I have, I don't really see anything that
indicates that doing some depth-to-temperature mapping makes much
sense. The thermoclines obviously *do* exist, but when they are clear
they are quite visible from the existing time-based model, and most of
the time they aren't clear at all and certainly not easy to associate
with depth because of delays and other noise.

Linus

[Willem Ferguson]

Post by Robert Helling
Hi,
yesterday, I had an hour of time and I played around with an idea that
I would like to get some feedback on (I already showed it to my wife
and she absolutely hated it).
The idea is not to show the temperature as a function of time as we
currently do it but rather plot it against depth. I find it much less
interesting what the temperature was 28 minutes into the dive but
rather want to know what was the temperature at 12m of depth and in
particular like to see the positions of thermoclines. So here is a

I love your idea.

wf

[Benjamin]

I really like the idea. Depending on where in the sea, the thermoclines can
be felt here, especially in the Mediterranean.


On Wed, 21 Nov 2018 at 12:23, Willem Ferguson <

Post by Willem Ferguson

Post by Robert Helling
Hi,
yesterday, I had an hour of time and I played around with an idea that
I would like to get some feedback on (I already showed it to my wife
and she absolutely hated it).
The idea is not to show the temperature as a function of time as we
currently do it but rather plot it against depth. I find it much less
interesting what the temperature was 28 minutes into the dive but
rather want to know what was the temperature at 12m of depth and in
particular like to see the positions of thermoclines. So here is a

I love your idea.
wf
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[tormento]

Or, simpler, put depth instead of time on x-axis and have all other
variables showed in function of it...

Post by Benjamin
I really like the idea. Depending on where in the sea, the thermoclines
can be felt here, especially in the Mediterranean.
On Wed, 21 Nov 2018 at 12:23, Willem Ferguson <

Post by Willem Ferguson

Post by Robert Helling
Hi,
yesterday, I had an hour of time and I played around with an idea that
I would like to get some feedback on (I already showed it to my wife
and she absolutely hated it).
The idea is not to show the temperature as a function of time as we
currently do it but rather plot it against depth. I find it much less
interesting what the temperature was 28 minutes into the dive but
rather want to know what was the temperature at 12m of depth and in
particular like to see the positions of thermoclines. So here is a

I love your idea.
wf
--
This message and attachments are subject to a disclaimer.
Please refer to
http://upnet.up.ac.za/services/it/documentation/docs/004167.pdf
<http://upnet.up.ac.za/services/it/documentation/docs/004167.pdf> for
full
details.
_______________________________________________
subsurface mailing list
http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface

_______________________________________________
subsurface mailing list
http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface