Temperature data acquired from the DOI/GTN-P Deep Borehole Array on the Arctic Slope of Alaska, 1973–2013

G D Clow

doi:10.5194/essd-6-201-2014

Abstract

Abstract. A homogeneous set of temperature measurements obtained from the DOI/GTN-P Deep Borehole Array between 1973 and 2013 is presented; DOI/GTN-P is the US Department of the Interior contribution to the Global Terrestrial Network for Permafrost (GTN-P). The 23-element array is located on the Arctic Slope of Alaska, a region of cold continuous permafrost. Most of the monitoring wells are situated on the Arctic coastal plain between the Brooks Range and the Arctic Ocean, while others are in the foothills to the south. The data represent the true temperatures in the wellbores and surrounding rocks at the time of the measurements; they have not been corrected to remove the thermal disturbance caused by drilling the wells. With a few exceptions, the drilling disturbance is estimated to have been on the order of 0.1 K or less by 1989. Thus, most of the temperature measurements acquired during the last 25 yr are little affected by the drilling disturbance. The data contribute to ongoing efforts to monitor changes in the thermal state of permafrost in both hemispheres by the Global Terrestrial Network for Permafrost, one of the primary subnetworks of the Global Terrestrial Observing System (GTOS). The data will also be useful for refining our basic understanding of the physical conditions in permafrost in Arctic Alaska, as well as providing important information for validating predictive models used for climate impact assessments. The processed data are available from the Advanced Cooperative Arctic Data and Information Service (ACADIS) repository at doi:10.5065/D6N014HK.

Highlights

The Arctic is highly sensitive to increases in global mean air temperature as exemplified by the large and persistent physical and biological changes currently being observed there (Jeffries et al, 2012, 2013)
The data contribute to ongoing efforts to monitor changes in the thermal state of permafrost in both hemispheres by the Global Terrestrial Network for Permafrost, one of the primary subnetworks of the Global Terrestrial Observing System (GTOS)
Realizing that the National Petroleum Reserve–Alaska (NPR-A) test wells provided a rare opportunity to obtain “undisturbed” temperatures in permafrost, the US Geological Survey (USGS) requested that 21 of the wells (Table 1) be completed in a manner that would allow high-precision temperature measurements to be made over many years

Summary

Introduction

The Arctic is highly sensitive to increases in global mean air temperature as exemplified by the large and persistent physical and biological changes currently being observed there (Jeffries et al, 2012, 2013). Realizing that the NPR-A test wells provided a rare opportunity to obtain “undisturbed” temperatures in permafrost, the US Geological Survey (USGS) requested that 21 of the wells (Table 1) be completed in a manner that would allow high-precision temperature measurements to be made over many years This involved filling the borehole casing with a nonfreezing fluid (diesel oil) above a cement plug installed 200–900 m below the surface, depending on the well. In 1999, the 21 NPR-A temperature-monitoring wells were incorporated into the Global Terrestrial Network for Permafrost (GTN-P), a new component of the Global Climate Observing System (GCOS) and one of its primary subnetworks, the Global Terrestrial Observing System (GTOS). Data from the DOI/GTN-P Deep Borehole Array will be useful for documenting how the thermal state of permafrost is changing on the Arctic Slope of Alaska in response to climate change. For the great majority of wells, the drilling disturbance is estimated

Borehole temperature measurements

Deconvolution

Temperature–depth profiles

Drilling disturbance

Temperature gradients m