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GEOPHYSICAL RESEARCH LETTERS,
VOL. 35,
L14309,
5 PP., 2008
doi:10.1029/2008GL034762
Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
Department of Geosciences, Princeton University, Princeton, New Jersey, USA
Zinifex Canada Inc., Ontario, Canada
Department of Geological Sciences, Indiana University, Bloomington, Indiana, USA
We have developed a borehole methodology to estimate formation thermal conductivity in situ with a spatial resolution of one meter. In parallel with a fiber-optic distributed temperature sensor (DTS), a resistance heater is deployed to create a controlled thermal perturbation. The transient thermal data is inverted to estimate the formation's thermal conductivity. We refer to this instrumentation as a Distributed Thermal Perturbation Sensor (DTPS), given the distributed nature of the DTS measurement technology. The DTPS was deployed in permafrost at the High Lake Project Site (67°22′N, 110°50′W), Nunavut, Canada. Based on DTPS data, a thermal conductivity profile was estimated along the length of a wellbore. Using the thermal conductivity profile, the baseline geothermal profile was then inverted to estimate a ground surface temperature history (GSTH) for the High Lake region. The GSTH exhibits a 100-year long warming trend, with a present-day ground surface temperature increase of 3.0 ± 0.8°C over the long-term average.
Received 21 May 2008; accepted 27 June 2008; published 30 July 2008.
Citation: (2008), Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor, Geophys. Res. Lett., 35, L14309, doi:10.1029/2008GL034762.
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