HR: 1340h
AN: PP43A-1001    [Abstracts]
TI: North American boreholes and GCM paleotemperatures: New comparison methodology
AU: * Stevens, M B
EM: bstevens@stfx.ca
AF: Environmental Sciences Research Centre, St. Francis Xavier University, 1 West Street, Antigonish, NS B2G2W5, Canada
AU: González-Rouco, J F
EM: fidelgr@fis.ucm.es
AF: Departamento de Astrofísica y CC. de la Atmósfera, Universidad Complutense de Madrid, Ciudad Universitaria, Madrid, 28040, Spain
AU: Beltrami, H
EM: hugo@stfx.ca
AF: Environmental Sciences Research Centre, St. Francis Xavier University, 1 West Street, Antigonish, NS B2G2W5, Canada
AB: Subsurface temperatures obtained from boreholes yield a direct, diffused record of past temperatures at local scales. When grouped into ensembles, average subsurface temperature profiles provide robust representations of past climate for large regions. With the availability of more computing power to run state-of-the-art General Circulation Models (GCMs), paleoclimatic simulations spanning the last millennium now exist. By forward-diffusing these paleotemperatures, comparison between the two data sets can be facilitated. The standard method for comparing two temperature profiles, modeled or measured, is via their root mean square (RMS) difference. This method gives equal weight to all depths, despite the fact that heat diffusion is a non-linear process. In this work, two additional criteria are implemented to complement RMS difference: the depth of major trend reversal (τ), and the magnitude of trend seen above (since) this reversal point (δ). Excellent agreement between externally forced ECHO-g integrations and subsurface temperatures is demonstrated in most of the regions studied. The implications of selecting an initial climate reference state are discussed
DE: 1600 GLOBAL CHANGE
DE: 1622 Earth system modeling (1225)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting