25 Volcanic Hazards: Products, Processes, and Perspectives (Posters)

Thursday, 19 May 2016
8:00 AM - 5:00 PM
Clearwater Room

QUANTIFYING ERRORS IN HEAT FLUX MEASUREMENTS USING A VERTICAL SEQUENCE OF THERMOCOUPLE SENSORS

Paper number: 25-2
Program: Theme Sessions
Time: 8:00 AM – 5:00 PM

Authors

Abstract

Estimating the heat flux at the land surface in geothermal areas can be a difficult

task. In part, this is due to the fact that the thermal conductivity of the soils is

spatially variable. More importantly, the time-varying atmospheric boundary condition

propagates a quasi-periodic signal into the subsurface, causing the near surface flux to

vary temporally such that it generally reverses on a diurnal time-scale. Under these

conditions, the most accurate way to estimate the annual average heat flux is to install a

vertical sequence of thermocouple sensors in the shallow subsurface, usually consisting

of four to six sensors distributed over about 1 m of depth. With accurate data on the

subsurface temperature profile and the soil thermal conductivity, it is possible to correct

for the time-varying surface boundary condition. However, it is common practice to

attach the thermocouple sensors to a metal rod, which is then driven into the soils,

and the perturbation introduced to the near-surface temperature profile has not been

previously evaluated. Here, we evaluate the impact of introducing a high-conductivity

element on soil heat-transfer, and offer guidelines for collecting shallow temperature

profile time-series data.

Geological Society of America Abstracts with Programs. Vol. 48, No. 6

doi: 10.1130/abs/2016RM-276188

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