Impact of ocean model resolution on CCSM climate simulations

Kirtman, Ben P.; Bitz, Cecilia M.; Bryan, Frank O.; Collins, William D.; Dennis, John M.; Hearn, N.; Kinter, James L.; Loft, Richard; Rousset, Clément; Siqueira, Léo; Stan, Cristiana; Tomas, Robert A.; Vertenstein, Mariana

doi:10.1007/s00382-012-1500-3

Cited by 218 publications

(285 citation statements)

References 54 publications

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“…In contrast, when the ocean model uses a coarse grid (1.0° or coarser), the opposite is found (Kirtman et al 2012). These results point to the high possibility that frontal-and mesoscale air-sea interactions are poorly represented in CMIP5 models, consistent with the CMIP3 analysis by Maloney and Chelton (2006), with potential consequences for the fidelity of simulations of the hydrological cycle.…”

Section: The Global Hydrological Cyclementioning

confidence: 63%

The Benefits of Global High Resolution for Climate Simulation: Process Understanding and the Enabling of Stakeholder Decisions at the Regional Scale

Roberts

Vidale

Senior

et al. 2018

Bulletin of the American Meteorological Society

128

107

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The time scales of the Paris Climate Agreement indicate urgent action is required on climate policies over the next few decades, in order to avoid the worst risks posed by climate change. On these relatively short time scales the combined effect of climate variability and change are both key drivers of extreme events, with decadal time scales also important for infrastructure planning. Hence, in order to assess climate risk on such time scales, we require climate models to be able to represent key aspects of both internally driven climate variability and the response to changing forcings. In this paper we argue that we now have the modeling capability to address these requirements—specifically with global models having horizontal resolutions considerably enhanced from those typically used in previous Intergovernmental Panel on Climate Change (IPCC) and Coupled Model Intercomparison Project (CMIP) exercises. The improved representation of weather and climate processes in such models underpins our enhanced confidence in predictions and projections, as well as providing improved forcing to regional models, which are better able to represent local-scale extremes (such as convective precipitation). We choose the global water cycle as an illustrative example because it is governed by a chain of processes for which there is growing evidence of the benefits of higher resolution. At the same time it comprises key processes involved in many of the expected future climate extremes (e.g., flooding, drought, tropical and midlatitude storms).

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Section: The Global Hydrological Cyclementioning

confidence: 63%

The Benefits of Global High Resolution for Climate Simulation: Process Understanding and the Enabling of Stakeholder Decisions at the Regional Scale

Roberts

Vidale

Senior

et al. 2018

Bulletin of the American Meteorological Society

128

107

View full text Add to dashboard Cite

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“…S2). Kirtman et al (22) showed that the Arctic warming is associated with significant losses of sea ice in the simulation with high resolution of sea ice and ocean model components using CCSM3.5 (the forerunner to CCSM4). DeWeaver and Bitz (23) suggested the simulation of Arctic sea ice and surface winds changes significantly when the resolution of the atmospheric model component is increased.…”

Section: Methods and Resultsmentioning

confidence: 99%

Reducing spread in climate model projections of a September ice-free Arctic

Liu

Song

Horton

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

159

120

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This paper addresses the specter of a September ice-free Arctic in the 21st century using newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). We find that large spread in the projected timing of the September ice-free Arctic in 30 CMIP5 models is associated at least as much with different atmospheric model components as with initial conditions. Here we reduce the spread in the timing of an ice-free state using two different approaches for the 30 CMIP5 models: (i) model selection based on the ability to reproduce the observed sea ice climatology and variability since 1979 and (ii) constrained estimation based on the strong and persistent relationship between present and future sea ice conditions. Results from the two approaches show good agreement. Under a high-emission scenario both approaches project that September ice extent will drop to ∼1.7 million km 2 in the mid 2040s and reach the ice-free state (defined as 1 million km 2 ) in 2054-2058. Under a medium-mitigation scenario, both approaches project a decrease to ∼1.7 million km 2 in the early 2060s, followed by a leveling off in the ice extent.A rctic sea ice has undergone dramatic decline in recent years (1). The minimum sea ice extent set on September 16, 2012 (3.41 million km 2 , ref.2) was 48.5% below the long-term mean and broke the previous record minimum set on September 18, 2007. The last six years (2007)(2008)(2009)(2010)(2011)(2012) have featured the lowest September ice extents during the satellite era. This decline raises the specter of a September ice-free Arctic in the coming decades, which would have significant impacts on Arctic maritime activities and ecosystems, biogeochemical feedbacks, and extreme weather and climate in mid and high latitudes (3, 4).The Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) concluded that "Arctic sea ice responds sensitively to warming, . . . late-summer sea ice is projected to disappear almost completely towards the end of the 21st century under the A2 scenario in some models" (5). Subsequent research suggested the ice-free Arctic might occur from as early as the late 2030s to the end of the 21st century under the Special Report on Emissions Scenarios (SRES) A1B and A2 scenarios based on the IPCC AR4 model simulations (also referred to as the CMIP3). An abrupt reduction in sea ice cover (i.e., 2-6 million km 2 within a decade) during the 21st century seems to be a common feature in a number of climate projections by the IPCC AR4 models. This could result in ice-free September conditions (less than ∼1.5 million km 2 ) by 2040 according to one simulation from the Community Climate System Model (CCSM) (6). Using the observed September sea ice extent in 2007 as a starting point, together with the projections of a subset of the IPCC AR4 models that better reproduce the observed climatological September ice extent, one study suggested the Arctic could be ice-free in September (less than 1 million km 2 ) in the late 2030s (with a large uncertainty...

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“…especially in controlling the heat transport of boundary currents. For example, moving from 1° to 0.25° (eddy-permitting) resolution in the modern-day climate results in an enhanced western boundary current heat transport (Delworth et al, 2012), and this effect can cause substantially lower Arctic sea ice coverage (Hutchinson et al, 2015;Kirtman et al, 2012). Moving from 3° to 1° ocean resolution, while still not permitting eddies, would improve the representation of boundary currents and their associated 5 impacts on gateway transitions.…”

Section: Hypotheses 15mentioning

confidence: 99%