An Investigation of the Irregularity of El Nino in a Coupled GCM

Yukimoto, Seiji; Kitamura, Yoshiteru

doi:10.2151/jmsj.81.599

Cited by 11 publications

(20 citation statements)

References 49 publications

(49 reference statements)

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“…1 of Yukimoto et al 2001); however, the globally averaged heat-flux adjustment results in a much smaller value than that for MRI2.0. This is because the radiation budget is significantly improved, as described later.…”

Section: Spin-up and Flux Adjustmentmentioning

confidence: 80%

“…The fundamental framework of this version is the same as the previous version MRI-CGCM2.0 (Yukimoto et al 2001;hereafter MRI2.0). The following model description is applicable to both versions, except for the modifications summarized in Table 1.…”

Section: Description Of the Modelmentioning

confidence: 99%

“…The second-generation Coupled General Circulation Model (MRI-CGCM2) was developed at the Meteorological Research Institute (MRI), and released as version MRI-CGCM2.0 (Yukimoto et al 2001). The model was used for climate-change simulations, and some of the results were included in the Third Assessment Report (TAR) of the Intergovermental Panel on Climate Change (IPCC 2001).…”

Section: Introductionmentioning

confidence: 99%

“…MRI-CGCM2.0 has been used in many climate studies (e.g., Yukimoto and Kitamura 2003) since its release, in which several issues concerning the model's performance have been identified. One factor is that the model's climate sensitivity is at a lower boundary among the models used for IPCC TAR assessments, though it is not necessarily incorrect, at least in the present consensus.…”

Section: Introductionmentioning

confidence: 99%

“…Yukimoto et al (2005) imposed historical forcing from natural and anthropogenic sources to simulate the climate change in the twentieth century. They provided simulated climatic trends in the late twentieth century for various fields, including the global surface-air temperature (SAT) and atmospheric circulations, with good agreement with those in observed climate changes.…”

Section: Introductionmentioning

confidence: 99%

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Present-Day Climate and Climate Sensitivity in the Meteorological Research Institute Coupled GCM Version 2.3 (MRI-CGCM2.3)

Yukimoto¹,

Noda²,

Hosaka³

et al. 2006

Journal of the Meteorological Society of Japan

Self Cite

122

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A new version of the Meteorological Research Institute (MRI) coupled general circulation model MRI-CGCM2 (MRI2.3) is developed and compared with the previous version (MRI2.0). The cloud scheme includes diagnostic function for cloud amount separately specified for convective and layer clouds, which is one of the major modifications contributing to the improved model performance. MRI2.3 exhibits better agreement with the observations in many aspects of present-day climate simulations, including the global energy budget, meridional distributions of shortwave and longwave radiation at the top of the atmosphere, and geographical distributions of surface air temperature and precipitation. The effective climate sensitivity of each version is evaluated based on an experiment with a transient (1%/year) increase of carbon dioxide concentration. The effective climate sensitivity of MRI2.3 (2.9 K) is about twice that of MRI2.0 (1.4 K). The change in the cloud-forcing response, particularly for shortwave cloud forcing, is essential for increasing climate sensitivity. A difference in tropical low-level clouds over the subsidence regions contributes significantly to the difference in cloud-forcing changes in response to a climate change. Analyses based on circulation regimes, defined by the vertical velocity at the mid-troposphere, suggest that the cloud-forcing response in the tropics is controlled more by thermodynamic characteristics, such as changes of the stability in the lower troposphere, rather than by large-scale circulation changes, such as a change in the subsidence strength.

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Section: Spin-up and Flux Adjustmentmentioning

confidence: 80%

Section: Description Of the Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Present-Day Climate and Climate Sensitivity in the Meteorological Research Institute Coupled GCM Version 2.3 (MRI-CGCM2.3)

Yukimoto¹,

Noda²,

Hosaka³

et al. 2006

Journal of the Meteorological Society of Japan

Self Cite

122

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Are historical records sufficient to constrain ENSO simulations?

Wittenberg

2009

Geophysical Research Letters

481

389

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[1] A control simulation of the GFDL CM2.1 global coupled GCM, run for 2000 years with its atmospheric composition, solar irradiance, and land cover held fixed at 1860 values, exhibits strong interdecadal and intercentennial modulation of its ENSO behavior. To the extent that such modulation is realistic, it could attach large uncertainties to ENSO metrics diagnosed from centennial and shorter records -with important implications for historical and paleo records, climate projections, and model assessment and intercomparison. Analysis of the wait times between ENSO warm events suggests that such slow modulation need not require multidecadal memory; it can arise simply from Poisson statistics applied to ENSO's interannual time scale and seasonal phase-locking.

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Climate–Carbon Cycle Model Response to Freshwater Discharge into the North Atlantic

Obata¹

2007

Journal of Climate

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The response of a coupled climate-carbon cycle model to discharge of freshwater into the North Atlantic is investigated with regard to cold reversals caused by meltwater from northern continental ice sheets such as the Younger Dryas during the last deglaciation. The extreme case in which the North Atlantic thermohaline circulation ceases in several decades is discussed. In the preindustrial case, northern severe cooling is reproduced by the collapse of the Atlantic northward heat transport, and land carbon decreases because of a decrease in net primary production (NPP) by the cooling or precipitation decrease, resulting in a decrease in global air temperature and an increase in atmospheric carbon dioxide (CO 2 ) concentration. The atmospheric CO 2 increase by the land carbon decrease is consistent with a previous terrestrial vegetation model study and a minimum in ice core ␦ 13 CO 2 during the Younger Dryas. The atmospheric CO 2 increase in this model is less than 10 ppmv, consistent with the paleoclimatic records at the beginning of the Younger Dryas. This small increase results from the compensation between changes in CO 2 sources and sinks of the land and ocean carbon cycles, such as the decrease in both NPP and soil respiration by the cooling. In the postindustrial case with fossil fuel CO 2 emission, the same anomalies as the preindustrial case are found in the climate and the land carbon cycle in comparison with the control experiment without the freshwater discharge. After the termination of the freshwater discharge, the cold anomaly is globally reduced by the intense greenhouse effect of the increasing atmospheric CO 2 on the order of 2000 ppmv, despite the weak thermohaline circulation in the North Atlantic. In contrast to the preindustrial case, the atmospheric CO 2 concentration about 90 ppmv higher than the control experiment is caused mostly by the decrease in the ocean carbon uptake, which results from the decrease in the transport of anthropogenic carbon into the deep ocean by the collapse of the North Atlantic thermohaline circulation. The model results show the fact that there can be a case in the earth system where a decoupling can be seen between two environmental variables, air temperature and atmospheric CO 2 , that normally correlate with each other.

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An Investigation of the Irregularity of El Nino in a Coupled GCM

Cited by 11 publications

References 49 publications

Present-Day Climate and Climate Sensitivity in the Meteorological Research Institute Coupled GCM Version 2.3 (MRI-CGCM2.3)

Present-Day Climate and Climate Sensitivity in the Meteorological Research Institute Coupled GCM Version 2.3 (MRI-CGCM2.3)

Are historical records sufficient to constrain ENSO simulations?

Climate–Carbon Cycle Model Response to Freshwater Discharge into the North Atlantic

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