HR: 0800h
AN: GC51D-1095    [Abstracts]
TI: Subsurface thermal effects of deforestation and borehole climatology
AU: * Nitoiu, D
EM: dnitoiu@stfx.ca
AF: Environmental Sciences Research Centre, St Francis Xavier University, P.O. Box 5000, Antigonish, NS B2G 2W5 Canada
AU: Beltrami, H
EM: hugo@stfx.ca
AF: Environmental Sciences Research Centre, St Francis Xavier University, P.O. Box 5000, Antigonish, NS B2G 2W5 Canada
AB: Changes in land surface conditions such as deforestation or forest fires modify the energy balance at the ground surface. Such energy imbalances appear as subsurface transient thermal signals superimposed on the climatic signal and the steady state geothermal field. Removal of the forest canopy increases the solar radiation reaching the ground surface. The associated increase in albedo is compensated by a decrease in evapotranspiration and the ground gains energy causing the surface temperature to increase. In the context of the ground surface energy balance and the thermal regime of the subsurface, the forest floor organic matter layer acts as a thermal insulator and moisture-retaining layer covering the ground. The integrated transient thermal signals caused by the rearrangement of the energy budget at the air-ground interface and by the variation of forest floor organic matter layer after deforestation are propagated and recorded in the subsurface. In this study, we examine the effects of deforestation on borehole temperature data by applying a first-order correction method to the subsurface data. We simulate the ground surface temperature variation following deforestation using a combined power and exponential function, based on data obtained from a chronosequence study of the evolution of forest floor organic matter mass. We show that the effects of deforestation on the subsurface temperatures, though important, are much smaller than previously thought. The application of this correction to the borehole temperature data from areas affected by land use changes may allow their incorporation into climatological studies.
DE: 3322 Land/atmosphere interactions
DE: 3344 Paleoclimatology
DE: 1600 GLOBAL CHANGE (New category)
DE: 1620 Climate dynamics (3309)
DE: 1645 Solid Earth
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting