• Ocean and Polar Research
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• v.26 no.3
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• pp.501-506
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• 2004

The observational proxy estimates suggest that the North Atlantic overturning stream function associated with the North Atlantic Deep Water (NADW) production and outflow was substantially weaker during the last glacial maximum (LGM) than that observed under present conditions. The impact of the changes in overturning circulation on the glacial carbon budget is investigated using a box model. The carbon box model reveals that the atmospheric $CO_2$ concentration is more sensitive to change in the overturning circulation of the North Atlantic than that of the Southern Ocean, especially when North Atlantic overturning becomes weaker. For example, when the strength of the North Atlantic overturning circulation is halved, the atmospheric $CO_2$ concentration is reduced by 50ppm of that associated with the accumulation of $CO_2$ in the deep ocean. This result implies that a weaker North Atlantic overturning circulation may play an important role in the lowering of LGM atmospheric $CO_2$ concentration.

• Journal of the Korean Geophysical Society
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• v.9 no.2
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• pp.135-145
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• 2006

The surface temperature and hydrological budget for the last glacial maximum (LGM) is simulatedwith an atmospheric general circulation model of NCAR CCM3 at spectral truncation of T170, corespondingto a grid cel size of roughly 75 km. LGM simulations were forced with the reconstructed CLIMAP sea surface temperatures, sea ice distribution, ice sheet topography, reduced CO2, and orbital parameters.oC in winter, 5.6oC in sumer,and 6oC annual-mean. The decrease of surface temperature leads to a weakening of the hydrologicalcycle. Global-mean precipitation decreases by about 14% in winter, 17% in summer, and 13% annually.However, some regions such as the U.S., southern Europe, northern and eastern Africa, and the SouthAmerica appear to be weter in the LGM winter and Canada and the Midle East are weter in sumer. model captures detailed climate features over land.

• The Korean Journal of Quaternary Research
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• v.20 no.1 s.26
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• pp.51-66
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• 2006

The climate of the last glacial maximum (LGM) in northeast Asia is simulated with an atmospheric general circulation model of NCAR CCM3 at spectral truncation of T170, corresponding to a grid cell size of roughly 75 km. Modern climate is simulated by a prescribed sea surface temperature and sea ice provided from NCAR, and contemporary atmospheric CO2, topography, and orbital parameters, while LGM simulation was forced with the reconstructed CLIMAP sea surface temperatures, sea ice distribution, ice sheet topography, reduced $CO_2$, and orbital parameters. Under LGM conditions, surface temperature is markedly reduced in winter by more than $18^{\circ}C$ in the Korean west sea and continental margin of the Korean east sea, where the ocean exposed to land in the LGM, whereas in these areas surface temperature is warmer than present in summer by up to $2^{\circ}C$. This is due to the difference in heat capacity between ocean and land. Overall, in the LGM surface is cooled by $4{\sim}6^{\circ}C$ in northeast Asia land and by $7.1^{\circ}C$ in the entire area. An analysis of surface heat fluxes show that the surface cooling is due to the increase in outgoing longwave radiation associated with the reduced $CO_2$ concentration. The reduction in surface temperature leads to a weakening of the hydrological cycle. In winter, precipitation decreases largely in the southeastern part of Asia by about $1{\sim}4\;mm/day$, while in summer a larger reduction is found over China. Overall, annual-mean precipitation decreases by about 50% in the LGM. In northeast Asia, evaporation is also overall reduced in the LGM, but the reduction of precipitation is larger, eventually leading to a drier climate. The drier LGM climate simulated in this study is consistent with proxy evidence compiled in other areas. Overall, the high-resolution model captures the climate features reasonably well under global domain.

• Journal of Climate Change Research
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• v.1 no.1
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• pp.31-50
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• 2010

The Arctic climate change for the Last Glacial Maximum(LGM) occurred at 21,000 years ago (21ka) was investigated using simulation results of atmosphere-ocean coupled models from the second phase of the Paleoclimate Modelling Intercomparison Program(PMIP2). In the analysis, we used seven models, the NCAR CCSM of USA, ECHAM3-MPIOM of German Max-Planxk Institute, HadCM3M2 of UK Met Office, IPSL-CM4 of France Laplace Institute, CNRM-CM3 of France Meteorological Institute, MIROC3.2 of Japan CCSR at University of Tokyo, and FGOALS of China Institute of Atmospheric Physics. All the seven models reproduces the Arctic climate features found in the present climate at 0ka(pre-industrial time) in a reasonable degree in comparison to observations. During the LGM, the atmospheric $CO_2$ concentration and other greenhouse gases were reduced, the ice sheets were expanded over North America and northern Europe, the sea level was lowered by about 120m, and orbital parameters were slightly different. These boundary conditions were implemented to simulated LGM climate. With the implemented LGM conditions, the biggest temperature reduction by more than $24^{\circ}C$ is found over North America and northern Europe owing to ice albedo feedback and the change in lapse rate by high elevation. Besides, the expansion of ice sheets leads to the marked temperature reduction by more then $10^{\circ}C$ over the Arctic Ocean. The temperature reduction in northern winter is larger than in summer around the Arctic and the annual mean temperature is reduced by about $14^{\circ}C$. Compared to low mid-latitudes, the temperature reduction is much larger in high northern altitudes in the LGM. This results mirror the larger warming around the Artic in recent century. We could draw some information for the future under global warming from the knowledge of the LGM.