Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM*

Bromwich, David H.; Toracinta, E. Richard; Wei, Helin; Oglesby, Robert J.; Fastook, J. L.; Hughes, Terence J.

doi:10.1175/1520-0442(2004)017<3415:pmsotw>2.0.co;2

Cited by 132 publications

(77 citation statements)

References 62 publications

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“…This points towards a feature caused by changes in atmospheric circulation. Bromwich et al (2004) suggested a split jet stream pattern around the Laurentide Ice Sheet during the LGM. Favourable transport north or south of the Laurentide during different time periods could possibly be an explanation for the feature observed here.…”

Section: Annual Layer Signaturementioning

confidence: 99%

The Greenland Ice Core Chronology 2005, 15–42ka. Part 1: constructing the time scale

Andersen

Svensson

Johnsen

et al. 2006

Quaternary Science Reviews

645

329

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The Greenland Ice Core Chronology 2005, GICC05, is extended back to 42 ka b2k (before 2000 AD), i.e. to the end of Greenland Stadial 11. The chronology is based on independent multi-parameter counting of annual layers using comprehensive high-resolution measurements available from the North Greenland Ice Core Project, NGRIP. These are measurements of visual stratigraphy, conductivity of the solid ice, electrolytical melt water conductivity and the concentration of Na + , Ca 2+ , SO 4 2À , NO 3 À , NH 4 + . An uncertainty estimate of the time scale is obtained from identification of 'uncertain' annual layers, which are counted as 0.570.5 years. The sum of the uncertain annual layers, the so-called maximum counting error of the presented chronology ranges from 4% in the warm interstadial periods to 7% in the cold stadials. The annual accumulation rates of the stadials and interstadials are on average one-third and half of the present day values, respectively, and the onset of the Greenland Interstadials 2, 3, and 8, based on 20 year averaged d 18 O values, are determined as 23,340, 27,780, and 38,220 yr b2k in GICC05. r

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Section: Annual Layer Signaturementioning

confidence: 99%

The Greenland Ice Core Chronology 2005, 15–42ka. Part 1: constructing the time scale

Andersen

Svensson

Johnsen

et al. 2006

Quaternary Science Reviews

645

329

View full text Add to dashboard Cite

show abstract

“…The area of LIS decreased to abut 2.0 × 10 6 km 2 during 6.0-7.0 BP and has remained nearly unchanged since then. Because the LIS can significantly alternate the surface energy balance of the high latitude North America (Bromwich et al 2004), the larger area of North America covered by LIS before 7.0 BP likely over- rode the effect of Atlantic SST, thereby weakening the relationship between the SST and drought.…”

Section: Statistical Relationship Between Atlantic Sst and Persistentmentioning

confidence: 99%

Influence of Atlantic sea surface temperatures on persistent drought in North America

2010

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This study investigates the relationship between North Atlantic sea surface temperatures (SST) and persistent drought in North America using modern observations, proxy paleodata, and simulations from multiple climate models. The observational results show that persistent droughts in the Great Plains and the southwest North America are closely related to multidecadal variations of North Atlantic SST (Atlantic Multidecadal Oscillations, AMO). During the AMO warm (cold) phases, most of North America is dry (wet). This relationship is persistent since at least 1567 AD, as based on proxy SST for the North Atlantic and the reconstructed drought index for North America. On centennial timescales, proxy SST records from the North Atlantic and proxy drought records for North America suggest that major periods of AMO-like warm (cold) SST anomalies during the last 7.0 ka correspond to dry (wet) conditions in the Great Plains. The influence of North Atlantic SST on North American droughts is examined using simulations made by five global climate models. When forced by warm North Atlantic SST anomalies, all models captured significant drying over North America, despite some regional differences. Specifically, dry summers in the Great Plains and the southwest North America are simulated by all models. The precipitation response to a cold North Atlantic is much weaker and contains greater disagreement among the models. Overall, the ensemble of the five models could well reproduce the statistical relationship between the dry/wet fluctuations in the North America and North Atlantic SST anomalies. Our results suggest that North Atlantic SSTs are likely a major driver of decadal and centennial timescale circulation, including droughts, in North America. Possible mechanisms that connect North Atlantic SST with North American drought, as well as interactions between North Atlantic and tropical Pacific SST and their relative roles on drought are also discussed.

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“…LGM cycles in the past 500 kyr are around 100 kyr (Hays et al, 1976;Imbrie and Imbrie, 1980); nevertheless, cycles between 80 and 120 kyr are not unusual (Huybers and Wunsch, 2005). During LGM the North American ice sheet was known to be dry (Bromwich et al, 2004); therefore, a constant LGM climate forcing beginning at an ice-free hemisphere takes longer to establish a fully grown North American ice sheet.…”

Section: Summary and Discussionmentioning

confidence: 99%

An ice sheet model of reduced complexity for paleoclimate studies

2016

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Abstract. IceBern2D is a vertically integrated ice sheet model to investigate the ice distribution on long timescales under different climatic conditions. It is forced by simulated fields of surface temperature and precipitation of the Last Glacial Maximum and present-day climate from a comprehensive climate model. This constant forcing is adjusted to changes in ice elevation. Due to its reduced complexity and computational efficiency, the model is well suited for extensive sensitivity studies and ensemble simulations on extensive temporal and spatial scales. It shows good quantitative agreement with standardized benchmarks on an artificial domain (EISMINT). Present-day and Last Glacial Maximum ice distributions in the Northern Hemisphere are also simulated with good agreement. Glacial ice volume in Eurasia is underestimated due to the lack of ice shelves in our model.The efficiency of the model is utilized by running an ensemble of 400 simulations with perturbed model parameters and two different estimates of the climate at the Last Glacial Maximum. The sensitivity to the imposed climate boundary conditions and the positive degree-day factor β, i.e., the surface mass balance, outweighs the influence of parameters that disturb the flow of ice. This justifies the use of simplified dynamics as a means to achieve computational efficiency for simulations that cover several glacial cycles. Hysteresis simulations over 5 million years illustrate the stability of the simulated ice sheets to variations in surface air temperature.

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Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM*

Cited by 132 publications

References 62 publications

The Greenland Ice Core Chronology 2005, 15–42ka. Part 1: constructing the time scale

The Greenland Ice Core Chronology 2005, 15–42ka. Part 1: constructing the time scale

Influence of Atlantic sea surface temperatures on persistent drought in North America

An ice sheet model of reduced complexity for paleoclimate studies

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