Evaluation of the sea ice simulation in a new coupled atmosphere‐ocean climate model (HadGEM1)

McLaren, A. J.; Banks, Helene T.; Durman, C. F.; Gregory, Jonathan M.; Johns, T. C.; Keen, Ann; Ridley, Jeff; Roberts, Malcolm; Lipscomb, William H.; Connolley, William M.; Laxon, Seymour W.

doi:10.1029/2005jc003033

Cited by 76 publications

(60 citation statements)

References 48 publications

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“…Investigation of the seasonal biases in West Antarctic climate of some of the bestperforming and worst-performing models was consistent with this. However, the realistic simulation of the seasonal cycle of sea ice presents a number of problems for climate models besides the correct representation of the atmosphere component, namely the correct representation of ocean currents and the complicated thermodynamical and dynamical processes within the ice pack (e.g., McLaren et al 2006). Turner et al (2013a) showed that the majority of the CMIP5 models have a seasonal cycle of sea ice extent that differs markedly from the observations, whereas Zunz et al (2012) showed that the CMIP5 multimodel mean underestimates (overestimates) the SIE in the ABS and Ross Sea sectors over the period from 1979 to 2005 in February (September), which are the months where the sea ice cover reaches its minimum (maximum).…”

Section: Discussionmentioning

confidence: 99%

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

et al. 2013

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In contrast to earlier studies, the authors describe the climatological deep low pressure system that exists over the South Pacific sector of the Southern Ocean, referred to as the Amundsen-Bellingshausen Seas low (ABSL), in terms of its relative (rather than actual) central pressure by removing the background areaaveraged mean sea level pressure (MSLP). Doing so removes much of the influence of large-scale variability across the ABSL sector region (e.g., due to the southern annular mode), allowing a clearer understanding of ABSL variability and its effect on the regional climate of West Antarctica. Using ECMWF Interim ReAnalysis (ERA-Interim) fields, the annual cycle of the relative central pressure of the ABSL for the period from 1979 to 2011 shows a minimum (maximum) during winter (summer), differing considerably from the earlier studies based on actual central pressure, which suggests a semiannual oscillation. The annual cycle of the longitudinal position of the ABSL is insensitive to the background pressure, and shows it shifting westward from ;2508 to ;2208E between summer and winter, in agreement with earlier studies. The authors demonstrate that ABSL variability, and in particular its longitudinal position, play an important role in controlling the surface climate of West Antarctica and the surrounding ocean by quantifying its influence on key meteorological parameters. Examination of the ABSL annual cycle in 17 CMIP5 climate models run with historical forcing shows that the majority of them have definite biases, especially in terms of longitudinal position, and a correspondingly poor representation of West Antarctic climate.

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Section: Discussionmentioning

confidence: 99%

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

et al. 2013

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“…As melting 1 m of sea ice will reduce pCO 2 levels by 14 µatm in a 20 m water column according to the calculations above, ∼4 m of sea ice would need to melt locally to explain the low pCO 2 concentrations in the water column. In polynya areas the sea ice production is usually much greater than indicated by the annual sea ice thickness due to the continued production of ice (McLaren, 2006). The local ice production at POLY I is thus likely responsible for much more larger ice growth than the April-May ice thickness of 1.4-1.6 m usually observed at ICE I .…”

Section: Role Of Ikaite In Seawater Co 2 System and Gas Exchangementioning

confidence: 96%

Ikaite crystal distribution in winter sea ice and implications for CO<sub>2</sub> system dynamics

et al. 2013

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Abstract. The precipitation of ikaite (CaCO 3 ·6H 2 O) in polar sea ice is critical to the efficiency of the sea ice-driven carbon pump and potentially important to the global carbon cycle, yet the spatial and temporal occurrence of ikaite within the ice is poorly known. We report unique observations of ikaite in unmelted ice and vertical profiles of ikaite abundance and concentration in sea ice for the crucial season of winter. Ice was examined from two locations: a 1 m thick land-fast ice site and a 0.3 m thick polynya site, both in the Young Sound area (74 • N, 20 • W) of NE Greenland. Ikaite crystals, ranging in size from a few µm to 700 µm, were observed to concentrate in the interstices between the ice platelets in both granular and columnar sea ice. In vertical sea ice profiles from both locations, ikaite concentration determined from image analysis, decreased with depth from surface-ice values of 700-900 µmol kg −1 ice (∼25 × 10 6 crystals kg −1 ) to values of 100-200 µmol kg −1 ice (1-7 × 10 6 crystals kg −1 ) near the sea ice-water interface, all of which are much higher (4-10 times) than those reported in the few previous studies. Direct measurements of total alkalinity (TA) in surface layers fell within the same range as ikaite concentration, whereas TA concentrations in the lower half of the sea ice were twice as high. This depth-related discrepancy suggests interior ice processes where ikaite crystals form in surface sea ice layers and partly dissolve in layers below. Melting of sea ice and dissolution of observed concentrations of ikaite would result in meltwater with a pCO 2 of <15 µatm. This value is far below atmospheric values of 390 µatm and surface water concentrations of 315 µatm. Hence, the meltwater increases the potential for seawater uptake of CO 2 .

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“…The atmosphere has 38 vertical levels with a model top at 39 km. Detailed description of the model formulation can be found in Shaffrey et al (2009, Martin et al (2006), McLaren et al (2006) and references therein.…”

Section: Higem Climate Modelmentioning

confidence: 99%

Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

et al. 2016

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exhibit biases in cloud structure, with more clouds at lower altitudes than those observed in ISCCP in the warm conveyor belt region. As a result, latent heat release in ERAI is concentrated at lower altitudes. CloudSat indicates that much precipitation may be produced at too low an altitude in both HiGEM and ERAI, particularly ERAI, and neither capture observed variability in precipitation intensity. The potential vorticity structure in composite extratropical cyclones in HiGEM and ERAI is also compared. A more pronounced tropopause ridge evolves in HiGEM on the leading edge of the composite as compared to ERAI. One future area of research to be addressed is what impact these biases in the representation of latent heating have on climate projections produced by HiGEM. The biases found in ERAI indicate caution is required when using reanalyses to study cloud features and precipitation processes in extratropical cyclones or using reanalysis to evaluate climate models' ability to represent their structure.

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Evaluation of the sea ice simulation in a new coupled atmosphere‐ocean climate model (HadGEM1)

Cited by 76 publications

References 48 publications

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

Ikaite crystal distribution in winter sea ice and implications for CO<sub>2</sub> system dynamics

Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

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Evaluation of the sea ice simulation in a new coupled atmosphere‐ocean climate model (HadGEM1)

Cited by 76 publications

References 48 publications

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

The Influence of the Amundsen–Bellingshausen Seas Low on the Climate of West Antarctica and Its Representation in Coupled Climate Model Simulations

Ikaite crystal distribution in winter sea ice and implications for CO&lt;sub&gt;2&lt;/sub&gt; system dynamics

Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

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Ikaite crystal distribution in winter sea ice and implications for CO<sub>2</sub> system dynamics