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Andrew H. MacDougall et al.: Quantification of subsurface heat storage in a GCM simulation

Geophysical Research Letters, Vol. 35, L13702, doi:10.1029/2008GL034639, 2008

Quantification of subsurface heat storage in a GCM simulation


Andrew H. MacDougall¹, J. Fidel González-Rouco², M. Bruce Stevens¹, and Hugo Beltrami¹

¹Environmental Sciences Research Centre, St. Francis Xavier University, Antigonish, Nova Scotia, Canada.

²Departamento de Astrofísica y Ciencias de la Atmósfera, Universitas Complutense de Madrid, Madrid, Spain.

Abstract

Shallow bottom boundary conditions (BBCs) in the soil components of general circulation models (GCMs) impose artificial limits on subsurface heat storage. To assess this problem we estimate the subsurface heat content from two future climate simulations and compare to that obtained from an offline soil model (FDLSM) driven by GCM skin temperatures. FDLSM is then used as an offline substitute for the subsurface of the GCM ECHO-G. With a 600-m BBC and driven by ECHO-G future temperatures, the FDLSM subsurface absorbs 6.2 (7.5) times more heat than the ECHO-G soil model (10 m deep) under the Intergovernmental Panel on Climate Change (IPCC) A2 (B2) emission scenario. This suggests that shallow BBCs in GCM simulations may underestimate the heat stored in the subsurface, particularly for northern high latitudes. This effect could be relevant in assessing the energy balance and climate change in the next century.

(Received 9 May 2008; accepted 3 June 2008; published 4 July 2008.)

Keywords: climate, general circulation model, subsurface heat content

Index Terms: 1620 Global Change: Climate dynamics (0429, 3309); 1622 Global Change: Earth system modeling (1225); 1626 Global Change: Global climate models (3337, 4928); 1631 Global Change: Land/atmosphere interactions (1218, 1843, 3322); 1645 Global Change: Solid Earth (1225).

Citation: MacDougall, A. H., J. F. González-Rouco, M. B. Stevens, and H. Beltrami (2008), Quantification of subsurface heat storage in a GCM simulation, Geophys. Res. Lett., 35, L13702, doi:10.1029/2008GL034639.