Last I was aware, they were mostly Onset HOBO loggers (and much longer ago, Ryan Tempmentors). I can't remember the resolution or temperature range, but I'm sure someone will have that information. The sampling rate depends on the geyser and how much detail is desired ("It erupted around 1:30 last night" vs. "It erupted for approximately three minutes and 30 seconds at approximately 1:24 a.m."). The thermistors are not not placed in the geysers--they're generally placed in the runoff channels, so what gets recorded is strictly output. Eruptions appear as sudden spikes in the temperature data. 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 worth noting that for most of the loggers, particularly those in channels with a frequent or constant small flow of water, the ambient air temperature can strongly affect the readings absent the massive flow of an eruption, to the point that for some (Plume comes to mind) it's possible to pick out day/night and seasonal cycles from the data. 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. David Schwarz <div class="gmail_quote">On Fri, Jun 5, 2009 at 5:56 PM, Davis, Brian L. <<a href="mailto:brdavis@iusb.edu">brdavis@iusb.edu</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> I was curious how exactly the geysers are electronically logged. Where could I find out the which commercial unit is used, and what the time and temperature resolution is that they generally log at? I'm guessing (and it's just a guess) that these are something like Onset water temperature loggers (I used them in my thesis work), that end up generating a series of temperature measurements at fixed time intervals, but I'm not sure what intervals are used (and, consequently, how often they need to be downloaded). The other thing I was wondering is how the data is reduced - if it's just a time series, what exactly is used to signify "in eruption", and what automated process extracts the data from the files (or is it done manually... ugh?). I'm curious how much is can be extracted from these files, and what the raw data looks like. My motivation is to try to see what a "model geyser" looks like under those conditions. I've got some odd and interesting models I'm trying to understand, with multiple eruption styles, bimodel intervals, etc. But I'm trying to interpret these as a datalogger or viewer might "see" them. Along those lines, what is the most recent scholarly review article of geyser dynamics? These models are doing lots of interesting things I wasn't expecting, but I'm not sure what's going on yet, or if they even apply... for one thing, I suspect convective heating in the conduit dominates in most natural geysers, yet this is devilishly hard to get to function in a small model... yet there's still some interesting stuff going on, and evidence for at least some convective heating even in 1/2" diameter conduits, and I'm trying to work up to wider ones (3/4" works, and I might be able to get into 1" conduits with some careful work). -- Brian Davis_______________________________________________ Geysers mailing list <a href="mailto:Geysers@lists.wallawalla.edu">Geysers@lists.wallawalla.edu</a> <a href="https://lists.wallawalla.edu/mailman/listinfo/geysers" target="_blank">https://lists.wallawalla.edu/mailman/listinfo/geysers</a> </blockquote></div>