[Geysers] Re: Data loggers and eruption extraction... and models

[Ralph Taylor]

Most of the temperature readings are at 8-bit resolution to allow for more
data to be stored; this gives about half a degree Celsius resolution.
Accuracy is another matter--the sensors are calibrated initially, but as
time passes they degrade.  The high resolution mode is 12-bit and gives
better than 0.1 degree C resolution.

It is possible to see preplay for many geysers, and there are indeed
apparently periodic variations in temperature in many of the datasets.  I
have not done any Fourier analysis, but have become very interested in the
short temperature cycles that many geysers exhibit.  Daisy is a good
example, with cyclic rise and fall in water level and boiling intensity.
Oblong is another, and Grand is yet another.

There is a lot of data waiting to be analyzed!

Ralph Taylor 

-----Original Message-----
From: geysers-bounces at lists.wallawalla.edu
[mailto:geysers-bounces at lists.wallawalla.edu] On Behalf Of Davis, Brian L.
Sent: Monday, June 08, 2009 5:06 PM
To: geysers at lists.wallawalla.edu
Subject: [Geysers] Re: Data loggers and eruption extraction... and models

David Schwarz wrote:

> Last I was aware, they were mostly Onset HOBO loggers (and much longer
> ago, Ryan Tempmentors).

Ralph Taylor was kind enough to reply off-list; yes, the current dataloggers
are evidently Onset Hobo Pro with an external temperature sensor. I'm not
sure yet the resolution (in temperature), but he mentioned that he often
sets them for 1 minute intervals.

> Depending on the geyser and the sensor location, it's sometimes also
> possible to get an approximate eruption duration, and even record
> non-eruptive or minor-eruptive activity (overflow and Turban cycles
> at Grand, hot periods at Giant and Fan and Mortar, etc.).

It's actually some of this "minor-eruptive" activity that I'm curious to see
(which is why I need the actual data, not the reduced data). It's a shame
there's not a good way to monitor the pressure within the pool, as that
could be interpreted in terms of water level. There are certainly pressure
sensor that have sub-centimeter water depth resolution, but they would of
course need to be in the pool, which I suspect would be very hard to do and
keep the Park happy about things; a very thin clear plastic tube would work,
but it still might be visible, and even made of Tygon would occasionally
need to be replaced. This was essentially how Old Faithful was instrumented
with pressure sensors if memory serves (only the tubes went down, not the
sensors themselves) for the in-conduit measurements. Pool surface
temperature might actually be easy to get, in a very non-intrusive way,
using an infrared thermometer from a distance.

> Detailed analysis of the data beyond extracting eruption times
> and other well-defined features therefore has a tendency to
> tell the analyst more about local weather patterns than about
> geysers.

True, although I wonder if anyone has ever done a Fourier analysis of the
data to look for essentially "harmonics" in the series. For an eruption,
they're going to be invisible... for a bunch of eruptions, expanded around a
well-defined point, they might not be.

In some cases, some very minor variations in the model conduit give some
surprisingly complex and interesting behaviors. For instance, making the
upper portion of a simple conduit wide (larger diameter) made for a system
that looked a lot like Turban-Grand in that there would be a quiet
post-eruption phase, followed by a series of "minor" eruptions of very
periodic nature, one of which ultimately resulted in a "major" eruption.
This was from a single-vent model, but it's still interesting. A system that
uses a "bedding plane" style geometry (a section that goes horizontal back
over itself in a very small vertical distance) also has these periodic
"pre-plays", but with the further interesting thing that the post-eruptive
"quiet phase" is ended by a significant (but not full) eruption (restart?).
I've barely touched on the plumbing variations, but I've seen how a steam
bubble can turn an erupting vent into a steaming pool as well.

There are a lot of problems with these models (no cold, slow recharge as
yet, convection within the conduit difficult to determine, and only one or
two heat sources, always at the same depth, and only one vent so far), but
there is a lot of almost eerily familiar behavior lurking in the results.
I'm just not sure how relevant it is yet (but it sure is fun). 

-- 
Brian Davis

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