Reconstruction of high resolution ground temperature histories combining dendrochronological and geothermal data

In an attempt to obtain robust records of past climatic variations, geothermal temperature-depth data have been combined with dendrochronological data to yield high resolution ground temperature histories. Since the resolution of the dendrochronological record and the ground temperature history inferred from geothermal data are different, comparison of these records is made possible by multiplying the dendrochronological data by the model resolution matrix for the geothermal data inversion. Under this condition, we find that a simple transformation between tree-ring indices and ground temperature changes allows us to interpret tree-ring widths in terms of ground temperatures, thus yielding a high resolution ground temperature history which explains the observed subsurface temperature regime. The linear transformation relating the ground temperature changes and average variations from the tree-ring chronology was found to beΔTg = 9.93 Iaverage.