Reptile & Amphibian Forums

Anyone have any tricks to measure temps more than a few feet down a burrow that you can't fit your hand in or see down?

I have a digital thermometer with a long wire with external probe, but I can't push it down reliably more than a few feet.

I'm thinking of using a small steel tape measure, taping the probe to that, and feeding that down.

HOBO data loggers help understand the relationships between surface and the underground temperature and pressure in Auyan-tepui Mountain, Guiana

--------------------------------------------------------------------------------

The Auyan-tepui "table" mountain in southern Venezuela

Caracas, Venezuela - The Venezuelan Speleological Society has recently returned from a caving expedition at the top of the Auyan-tepui mountain in southern Venezuela (the one that has the Angel's falls, the highest waterfall of the world). This is a table-mountain surrounded by jungle of the Guiana region of the Orinoco basin.

At the top of the mountain with an elevation of 1,450 meters above sea level, the Aonda Cave System was continued to be studied and explored, this cave is the deepest cave in the world opened in sandstone with -382 meters which is quite unusual since normal caves are developed in limestone.

Three sets of HOBO data loggers of temperature and pressure were positioned at three different locations to try to understand the relationship between the surface conditions and those encountered underground. One station was the surface under direct sun exposure, another 3 meters deep in a fracture with no direct sun and a third inside a vertical shaft at a depth of -80 meters.

The data loggers were active for fourteen days with measures each 16 minutes. The results of the temperature data show that the surface conditions are very variable as expected (with large daily variations, a maximum of 54°C at 2:00 PM, minimum of 14°C at 6:30 AM. The temperature at the -80 meters deep logger shows a minimum daily variation usually no larger than 0.8°C in a day keeping around the average of 17.5°C.

The pressure data loggers show a rather similar trend at surface and underground, but with more variation at the surface and smoother daily variation underground.

The data was processed by uni and multivariate statistics including cluster analysis (Fig 8) allowing to objectively interpret the daily variation.

In order to characterize the daily cycle in temperature and pressure, the measurements done at the same time during the 15 days (90 measurements per day) were averaged and plotted also with the maximum and minimum (Fig 9). Figure 14 shows such daily cycle for pressure at both surface (p-c-p) and underground (p-s-p) compared with the theoretical fluctuation (doted line) at this latitude.

The most useful way to process the data found in this work was that of its normalization to a range from 0 to 1, in that way it is easy to compare parameters of different units (as pressure and temperature) or even the same units but in different ranges of values. With this last procedure it is interpreted that the pressure varies in a similar way at the surface and 80 meters underground due to the more easy transmission of this condition from the external daily changes to the underground environment but reaching underground in a more damped and regular fashion (Fig 19B). In the case of air temperature a condition which is transmitted underground due to are currents the trend shown comparing the surface against the underground curves show an offset of nearly 12-14 hours (Fig 19A). Concluding that this is the amount of time needed for the surface air to reach the -80 meter depth.

You probably are'nt going that deep so your data at the surface worked out with the data from say 5' or so, could give you quite alot of information for averages of temperature and the time taken to reach them.
I used a plumbers snake with the probe taped to the end for burrow readings on DT.
Cheers

I've seen those HOBO and similar devices, and I didn't even consider that. I suppose I could attach some fishing line to it (so I can retreive it) and push it down into the burrow. Thanks for the idea.

If you have line of sight you could use a laser sighted temp gun.

Data loggers are also good...I project I was just on has had temp and humidity data loggers that are taking measurements once every four hours for the past year....It will be interesting to see the differences and collate that back to the audio recorders to get temps, and humidity when these frogs are calling.

Regards,
Scott Eipper