Session: Last Millennium & Past2K
Author: Francisco José Cuesta Valero / email@example.com / Environmental Sciences Program, Memorial University of Newfoundland, St. John's, NL, Canada and Climate & Atmospheric Sciences Institute, St. Francis Xavier University, Antigonish, NS, Canada
Co-author: Almudena García García, Environmental Sciences Program, Memorial University of Newfoundland, St. John's, NL, Canada Climate & Atmospheric Sciences Institute, St. Francis Xavier University, Antigonish, NS, Canada;
Hugo Beltrami, Climate & Atmospheric Sciences Institute, St. Francis Xavier University, Antigonish, NS, Canada and Centre ESCER pour l'étude et la simulation du climate à l'échelle régionale, Université du Québec à Montréal, Montréal, QC, Canada;
Eduardo Zorita, Institute of Coastal Research, Hemlholtz-Zentrum Geesthacht, Germany;
Control climate simulations aim to provide a stationary state to General Circulation Models (GCMs) under constant preindustrial conditions (piControl simulations). This stationary state is then used as initial conditions in GCM simulations to provide a stable and realistic climatology, reducing the potential bias in such simulations. However, it is difficult to provide a reference to assess the climatology of piControl simulations due to the lack of long-term preindustrial observations. We explore the use of long-term ground surface temperature estimates from borehole temperature profiles as an additional reference that may be useful for the initialization procedure of GCM simulations.
We compare five last millennium simulations and five preindustrial control simulations from the third phase of the Palaeoclimate Modelling Intercomparison Project (PMIP3) and the fifth phase of the Coupled Model Intercomparison Project (CMIP5) archives against estimates of long-term preindustrial ground surface temperatures from 514 borehole temperature profiles over North America. These long-term surface temperatures are retrieved from the quasi-equilibrium state of the subsurface thermal regime in each temperature profile, which is estimated from the deepest section of the profile. That is, the equilibrium state is recovered from the least affected part of the temperature profile by the recent changes in the surface energy balance. The subsurface temperatures at the bottom part of each profile depend linearly on depth, and the extrapolation of this linear behavior to the surface is interpreted as the long-term surface temperature (T0 temperature) at each borehole site.
Our results suggest that the ground surface temperature estimates from borehole data could be employed as a reference within piControl simulations to enhance the quality of the initial conditions in GCM climate simulations.