BEST PRACTICES FOR SHALLOW GROUND TEMPERATURE MEASUREMENTS

Shallow ground temperature measurements are commonly used to analyze geothermally active areas. In many shallow ground temperature studies, researchers utilize temperature measurements at one meter depth on a sparse, irregularly spaced sampling interval. However, one meter depth can be quite invasive to fragile environments and take substantial time. We propose the use of temperature probes 25 cm in length on a set grid with high density spacing (e.g., 72 x 72 m with 3 x 3 m spacing). The high density sampling interval on a set grid is superior because it allows for the development of spatial correlation relationships, and because the uncertainty of the measured temperatures decreases proportional to the square root of the total number of data points collected.

We have found there are a number of potential pitfalls when collecting high resolution ground temperature measurements, and developed possible approaches for addressing them. Potential sources for error in shallow ground temperature measurements include: systematic error from thermometer calibration, various probe penetration depths, atmospheric conditions (e.g., evaporative cooling due to moisture in the atmosphere), and shallow standing water in the grid area. It is imperative to recognize and address these pitfalls when collecting shallow ground temperature data sets. We applied these guidelines while conducting several successful ground temperature surveys at Yellowstone National Park, WY.