Abstract
AbstractClimate-model biases in ocean heat transport (OHT) have been proposed as a major contributor to uncertainties in projections of sea ice extent. To better understand the impact of OHT on sea ice extent and compare it to that of atmospheric heat transport (AHT), an idealized, zonally averaged energy balance model (EBM) is developed. This is distinguished from previous EBM work by coupling a diffusive mixed layer OHT and a prescribed OHT contribution, with an atmospheric EBM and a reduced-complexity sea ice model. The ice-edge latitude is roughly linearly related to the convergence of each heat transport component, with different sensitivities depending on whether the ice cover is perennial or seasonal. In both regimes, Bjerknes compensation (BC) occurs such that the response of AHT partially offsets the impact of changing OHT. As a result, the effective sensitivity of ice-edge retreat to increasing OHT is only ~2/3 of the actual sensitivity (i.e., eliminating the BC effect). In the perennial regime, the sensitivity of the ice edge to OHT is about twice that to AHT, while in the seasonal regime they are similar. The ratio of sensitivities is, to leading order, determined by atmospheric longwave feedback parameters in the perennial regime. Here, there is no parameter range in which the ice edge is more sensitive to AHT than OHT.
Highlights
Sea ice is a major component of the climate system, influencing it through its enhanced surface reflectivity compared to the ocean, insulation of the oceans, and role in the thermohaline circulation (e.g., Barry et al 1993)
We develop a minimum-complexity, idealized climate model describing the dynamical processes controlling the latitude of the sea ice edge to explore the impacts of atmospheric heat transport (AHT) and ocean heat transport (OHT)
We focus on the parameters Ko, Ka, and Fbp, which allow us to determine the sensitivities of the ice edge to OHT and AHT
Summary
Sea ice is a major component of the climate system, influencing it through its enhanced surface reflectivity compared to the ocean, insulation of the oceans, and role in the thermohaline circulation (e.g., Barry et al 1993). Comprehensive general circulation models (GCMs) exhibit large intermodel spread in projections of sea ice extent in simulations of past, present, and future climate (Marzocchi and Jansen 2017; Turner et al 2013; Massonnet et al 2012), persisting across phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP) (Stroeve et al 2012) This leads to large uncertainties in the estimation of, for instance, when the Arctic may become seasonally ice free under various warming scenarios. We seek to understand which processes control the sensitivity of the sea ice cover to OHT on climatic scales, in comparison to that of the AHT, identifying mechanisms and parameters that set the relative sensitivities These insights are a step toward understanding the potential role of heat transport biases in the spread of sea ice extent in CMIP models, by providing a theoretical framework to interpret model.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
