Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 2 6 2006 10.5194/cpd-2-1075-2006 http://www.clim-past-discuss.net/2/1075/2006/ http://www.clim-past-discuss.net/2/1075/2006/cpd-2-1075-2006.html http://www.clim-past-discuss.net/2/1075/2006/cpd-2-1075-2006.pdf 1075 1104 2006-11-07 Differences between repeated borehole temperature logs in the southern Canadian Prairies-validating borehole climatology J. Majorowicz majorowicz@shaw.ca W. Skinner J. Safanda W. Gosnold Northern Geothermal, 105 Carlson Close, Edmonton, Alberta, T6R 2J8, Canada Climate Research Division, Environment Canada, Toronto, Ontario, M3H 5T4, Canada Geophysical Institute, Prague, Czech Republic University of North Dakota, Northern Plains Climate Research Centre, Grand Forks, ND, USA Temperature-depth (T-z) profiles from twenty-four shallow boreholes of less than 250 m in depth located in flat, semi-arid areas of the southern Canadian Prairie Provinces initially measured in the late 1980's and early 1990's and repeated between 2004 and 2006 show strong ground surface temperature (GST) warming signatures. GST changes of 0.1–0.2°C, and 0.4°C, are observed between the measurements for the shorter (decade) and longer (two decades) time spans, respectively. Borehole sites with repeated temperature logs are selected to demonstrate that multiple T-z profiles provide general agreement between GST warming and observed surface air temperature (SAT) warming measured at nearby historical climate stations. A comparison of measured changes from repeated temperature logs with those simulated from SAT forcing demonstrates the influence of SAT on the observed deviation of temperature with depth despite variations in snow cover. Repeated borehole measurements from the northern Great Plains of the USA also identify a similar positive temperature change but of lower magnitude. Temperature changes since 1900 in the southern Canadian Prairies and the adjoining northern Great Plains of the USA, as derived from the functional state inversion (FSI) of deeper borehole logs, average 2.5°C but show a strong latitudinal gradient. Baker, D. G. and Ruschy, D. L.: The recent warming in eastern Minnesota shown by ground temperatures, Geophys. Res. Lett., 20, 371–374, 1993. Bartlett, M. G., Chapman, D. S., and Harris, R. N.: Snow effects on North America ground temperatures, 1950–2002, J. Geophys. Res., 110, F03008 doi:10.1029/2005JF000293, 2005. Beach, R. D. W., Jones, F. W., and Majorowicz, J. A.: Heat flow and heat generation for the Churchill of Western Canadian Sedimentary basin, Geothermics, 16, 1–16, 1987. Carslaw, H. S. and Jaeger, J. C.: Conduction of Heat in Solids, Oxford Univ. Press, New York, 386 pp.,1959. Ferguson, G. and Woodbury, A. D.: The effect of climatic variability on estimates of recharge derived from temperature data ground water, Ground Water Res., 43, 837–842, 2005. Gosnold, W. D., Todhunter, P. E., and Schmidt, W.: The borehole temperature record of climate warming in the mid-continent of north America, Global Planet. Change, 15, 33–45, 1997. Gosnold, W., A., Dong, U., and Popham, J.: A test of borehole climatology, AGU Fall Meeting abstract, AN:PP52A-0659, 2005. Harris, R. N. and Gosnold, W. D.: Comparisons of borehole – depth profiles and and surface air temperatures in the northern plains of the USA Geophys. J. Int., 138, 541–548, 1999. Jessop, A. M.: Thermal Geophysics Developments in Solid Earth, Geophys., 17, Elsevier, 306 p., 1990. Lewis, T.: The effect of deforestation on ground surface temperatures, Global Planet. Change, 18, 1–13, 1998. Lewis, T. and Skinner, W.: Inferring climate change from underground temperatures: Apparent climatic stability and apparent climatic warming, Earth Interactions, 7, paper No. 9, 1–9, 2003. Lachenbruch, A. H.: Permafrost, The active layer and changing climate, US Geol. Surv. Open-File Report 94-694 Menlo Park, CA, 1994, 43 pp., 1994. Majorowicz, J. A. and Skinner, W. R.: Potential causes of differences between ground and surface air temperature warming across different ecozones in Alberta, Canada, Global Planet. Change, 15, 79–91, 1997. Majorowicz, J. A. and Safanda, J.: Measured versus simulated transients of temperature logs, J. Geophys. Eng., 4, 291–298, 2005. Majorowicz, J. A., Grasby, S., Ferguson, G., Safanda, J., and Skinner, W. R.: Paleoclimatic reconstructions in western Canada from borehole temperature logs: surface air temperature forcing and groundwater flow, Clim. Past, 2, 1–10, 2006a. Majorowicz, J. A., Safanda J., Harris, R., and Skinner, W. R.: Large ground surface temperature changes of the last three centuries inferred from borehole temperatures in the southern Canadian prairies-Saskatchewan, Global Planet. Change, 20, 227–241, 1999. Mann, M. E, and Schmidt, G. A.: Ground vs. Surface Air Temperature Trends: Implications for Borehole Surface Temperature Reconstructions, Geophys. Res. Lett., 30(12), 1607, doi:10.1029/2003GL017170, 2003. Mekis, E. and Hogg, W. D.: Rehabilitation and analysis of Canadian daily precipitation time series, Atmos.-Ocean, 37(1), 53–85, 1999. Reiter, M.: Possible ambiguities in subsurface temperature logs – Consideration of ground – water flow and ground surface temperature change, Pure Appl. Geophys., 162, 343–353, 2005. Shen, P, Yu and Beck, A. E.: Least squares inversion of borehole temperature measurements in functional space, J. Geophys. Res., 96, 19 965–19 979, 1991. Schmidt, W. L., Gosnold, W. D., and Enz, J. W.: A decade of air-ground temperature exchange from Fargo North Dakota, Global Planet. Change, 29, 311–325, 2001. Skinner, W. R. and Majorowicz, J. A.: Regional climatic warming and associated twentieth century land-cover changes in north-western North America, Clim. Res., 12, 39–52, 1999. Stieglitz, M., Romanovsky, V. E. and Osterkamp, T. E.: The role of snow cover in the warming of arctic permafrost, Geophys. Res. Lett., 30, 1721, doi:10,1029/2003GL017337, 2003. Todhunter, P. E. and Popham, J. L.: Relationship Between Snow Cover and Thermal Offset of Soil and Air Temperatures in the Great Plains of the United States, AGU Fall Abstracts, 2005. Vincent, L. and Gullett, D. W.: Canadian historical and homogeneous temperature datasets for climate change analyses, Int. J. Clim., 19, 1375–1388, 1999. Zhang, X., Vincent, L. A., Hogg, D. W., and Niitsoo, A.: Temperature and precipitation trends in Canada during the 20th century, Atmos.-Ocean, 38, 395–429, 2000.