A new coupled ice sheet/climate model: description and sensitivity to model physics under Eemian, Last Glacial Maximum, late Holocene and modern climate conditions

Abstract

Abstract. The need to better understand long-term climate/ice sheet feedback loops is motivating efforts to couple ice sheet models into Earth System models which are capable of long-timescale simulations. In this paper we describe a coupled model that consists of the University of Victoria Earth System Climate Model (UVic ESCM) and the Pennsylvania State University Ice model (PSUI). The climate model generates a surface mass balance (SMB) field via a sub-gridded surface energy/moisture balance model that resolves narrow ice sheet ablation zones. The ice model returns revised elevation, surface albedo and ice area fields, plus coastal fluxes of heat and moisture. An arbitrary number of ice sheets can be simulated, each on their own highresolution grid and each capable of synchronous or asynchronous coupling with the overlying climate model. The model is designed to conserve global heat and moisture. In the process of improving model performance we developed a procedure to account for modelled surface air temperature (SAT) biases within the energy/moisture balance surface model and improved the UVic ESCM snow surface scheme through addition of variable albedos and refreezing over the ice sheet.A number of simulations for late Holocene, Last Glacial Maximum (LGM), and Eemian climate boundary conditions were carried out to explore the sensitivity of the coupled model and identify model configurations that best represented these climate states. The modelled SAT bias was Correspondence to: J. G. Fyke (fykejere@myvuw.ac.nz) found to play a significant role in long-term ice sheet evolution, as was the effect of refreezing meltwater and surface albedo. The bias-corrected model was able to reasonably capture important aspects of the Antarctic and Greenland ice sheets, including modern SMB and ice distribution. The simulated northern Greenland ice sheet was found to be prone to ice margin retreat at radiative forcings corresponding closely to those of the Eemian or the present-day.

Simulation of the Greenland Ice Sheet over two glacial–interglacial cycles: investigating a sub-ice- shelf melt parameterization and relative sea level forcing in an ice-sheet–ice-shelf model

“…This is mostly due to the reduction in the estimated contribution from the Antarctic Ice Sheet (AIS), derived from both modelling and observational studies. In addition, glacial isostatic adjustment (GIA) modelling studies have estimated the contribution of the GrIS to the LGM GMSL budget to be ∼ 5 m (Lecavalier et al, 2014), whereas most ice-sheet modelling-based studies indicate significantly less (typically < 2.5 m; average < 1 m) (Fyke et al, 2011;Letreguilly et al, 1991;Ritz et al, 1996). These lower estimates are possibly caused by restricting the glacial maximum extent to the PD coastline.…”

The importance of insolation changes for paleo ice sheet modeling

“…However, RCMs must be forced at the lateral boundaries by output from past climate simulations with general circulation models (GCMs), which usually implies a fixed ice sheet surface elevation or strategies to circumvent this problem (e.g., Helsen et al, 2012;Edwards et al, 2014a, b). Attempts have also been made to directly couple ice sheet models and GCMs (e.g., Fyke et al, 2011;Lipscomb et al, 2013), but the high computational demands of both RCMs and GCMs currently limit long-term transient simulations to those using asynchronous coupling (Helsen et al, 2013) or other interpolation strategies (e.g., Stone et al, 2013).…”

Modeling the climatic implications and indicative senses of the Guliya δ&lt;sup&gt;18&lt;/sup&gt;O-temperature proxy record to the ocean–atmosphere system during the past 130 ka

“…The UVic Model is an intermediate-complexity coupled atmosphere-ocean model (Weaver et al, 2001) in which the atmospheric model comprises a single-layer energy-moisture balance model and the ocean component utilizes version 2.2 of the GFDL Modular Ocean Model with 19 vertical levels. The UVic Model can capture several major features of global surface temperature and precipitation and has been widely used in paleoclimate research (Weaver et al, 2001;Matthews et al, 2004;Stouffer et al, 2006;Weber et al, 2007;Fyke et al, 2011). Moreover, the UVic Model can also reproduce variations of temperature in China and the NH during the past millennium (Xiao et al, 2012).…”