scholarly journals PlioMIP2 simulations using the MIROC4m climate model

2020 ◽  
Author(s):  
Wing-Le Chan ◽  
Ayako Abe-Ouchi
Keyword(s):  
Boundary Conditions ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Second Phase ◽  
Climate Modelling ◽  
Model Intercomparison ◽  
Model Data

Abstract. The second phase of the Pliocene Model Intercomparison Project (PlioMIP2) has attracted many climate modelling groups in its continuing efforts to better understand the climate of the mid-Piacenzian warm period (mPWP) when atmospheric CO2 was last closest to present day levels. Like the first phase, PlioMIP1, it is an internationally coordinated initiative that allows for a systematic comparison of various models in a similar manner to PMIP. Model intercomparison and model-data comparison now focus specifically on the interglacial at marine isotope stage KM5c (3.205 Ma) and experimental design is not only based on new boundary conditions but includes various sensitivity experiments. In this study, we present results from long-term model integrations using the MIROC4m atmosphere-ocean coupled general circulation model, developed at the institutes CCSR/NIES/FRCGC in Japan. The core experiment, with CO2 levels set to 400 ppm, shows a warming of 3.1 °C compared to the Pre-Industrial, with two-thirds of the warming being contributed by the increase in CO2. Although this level of warming is less than that in the equivalent PlioMIP1 experiment, there is a slightly better agreement with proxy sea surface temperature (SST) data at PRISM3 locations, especially in the northern North Atlantic where there were large model-data discrepancies in PlioMIP1. Similar changes in precipitation and sea ice are seen and the Arctic remains ice-free in the summer. However, unlike PlioMIP1, the Atlantic Meridional Overturning Circulation (AMOC) is now stronger than that of the Pre-Industrial, even though increasing CO2 tends to weaken it. This stronger AMOC is a consequence of a closed Bering Strait in the PlioMIP2 paleogeography. Also, when present day boundary conditions are replaced by those of the Pliocene, the dependency of the AMOC strength on CO2 is significantly weakened. Sensitivity tests show that lower values of CO2 give a global SST which is overall more consistent with the PRISM3 SST field presented in PlioMIP1. Inclusion of dynamical vegetation and the effects of all realistic orbital configurations should be considered in future experiments using MIROC4m for the mPWP.

scholarly journals Pliocene Model Intercomparison Project (PlioMIP2) simulations using the Model for Interdisciplinary Research on Climate (MIROC4m)

2020 ◽  
Vol 16 (4) ◽  
pp. 1523-1545 ◽  
Author(s):  
Wing-Le Chan ◽  
Ayako Abe-Ouchi
Keyword(s):  
Boundary Conditions ◽  
Interdisciplinary Research ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Second Phase ◽  
Model Intercomparison ◽  
Model Data ◽  
Proxy Data ◽  
The Core ◽  
Intercomparison Project

Abstract. The second phase of the Pliocene Model Intercomparison Project (PlioMIP2) has attracted many climate modelling groups in its continuing efforts to better understand the climate of the mid-Piacenzian warm period (mPWP) when atmospheric CO2 was last closest to present-day levels. Like the first phase, PlioMIP1, it is an internationally coordinated initiative that allows for a systematic comparison of various models in a similar manner to the Paleoclimate Modelling Intercomparison Project (PMIP). Model intercomparison and model–data comparison now focus specifically on the interglacial at marine isotope stage KM5c (3.205 Ma), and experimental design is not only based on new boundary conditions but includes various sensitivity experiments. In this study, we present results from long-term model integrations using the MIROC4m (Model for Interdisciplinary Research on Climate) atmosphere–ocean coupled general circulation model, developed at the institutes CCSR, NIES and FRCGC in Japan. The core experiment, with CO2 levels set to 400 ppm, shows a warming of 3.1 ∘C compared to the pre-industrial period, with two-thirds of the warming being attributed to the increase in CO2. Although this level of warming is less than that in the equivalent PlioMIP1 experiment, there is slightly better agreement with proxy sea surface temperature (SST) data at PRISM3 (PRISM – Pliocene Research Interpretation and Synoptic Mapping) locations, especially in the northern North Atlantic where there were large model–data discrepancies in PlioMIP1. Similar spatial changes in precipitation and sea ice are seen and the Arctic remains ice-free in the summer in the core experiments of both phases. Comparisons with both the proxy SST data and proxy surface air temperature data from paleobotanical sites indicate a weaker polar amplification in model results. Unlike PlioMIP1, the Atlantic Meridional Overturning Circulation (AMOC) is now stronger than that of the pre-industrial period, even though increasing CO2 tends to weaken it. This stronger AMOC is a consequence of a closed Bering Strait in the PlioMIP2 paleogeography. Also, when present-day boundary conditions are replaced by those of the Pliocene, the dependency of the AMOC strength on CO2 is significantly weakened. Sensitivity tests show that lower values of CO2 give a global SST which is overall more consistent with the PRISM3 SST field presented in PlioMIP1, while SSTs at many of the PRISM4 sites are still too high to be reconciled with any of the model results. On the other hand, tropical Pacific SST in the core experiment agrees well with more recent proxy data, which suggested that PRISM3 SST there was overestimated. Future availability of climate reconstructions from proxy data will continue to help evaluate model results. The inclusion of dynamical vegetation and the effects of all possible extreme orbital configurations outside KM5c should be considered in future experiments using MIROC4m for the mPWP.

scholarly journals The FAMOUS climate model (versions XFXWB and XFHCC): description update to version XDBUA

2011 ◽  
Vol 4 (4) ◽  
pp. 3047-3065
Author(s):  
R. S. Smith
Keyword(s):  
Water Budget ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Model Description ◽  
Model Intercomparison ◽  
Ocean Atmosphere ◽  
Atmosphere General Circulation Model ◽  
Intercomparison Project ◽  
The Uk

Abstract. FAMOUS is an ocean-atmosphere general circulation model of low resolution, based on version 4.5 of the UK MetOffice Unified Model. Here we update the model description to account for changes in the model as it is used in the CMIP5 EMIC model intercomparison project (EMICmip) and a number of other studies. Most of these changes correct errors found in the code. The EMICmip version of the model (XFXWB) has a better-conserved water budget and additional cooling in some high latitude areas, but otherwise has a similar climatology to previous versions of FAMOUS. A variant of XFXWB is also described, with changes to the dynamics at the top of the model which improve the model climatology (XFHCC).

scholarly journals Simulating the mid-Pliocene climate with the MIROC general circulation model: experimental design and initial results

2011 ◽  
Vol 4 (4) ◽  
pp. 1035-1049 ◽  
Author(s):  
W.-L. Chan ◽  
A. Abe-Ouchi ◽  
R. Ohgaito
Keyword(s):  
Experimental Design ◽  
Boundary Conditions ◽  
General Circulation Model ◽  
General Circulation ◽  
Climate Models ◽  
Circulation Model ◽  
Sea Surface ◽  
Future Climate Change ◽  
Model Intercomparison ◽  
Initial Results

Abstract. Recently, PlioMIP (Pliocene Model Intercomparison Project) was established to assess the ability of various climate models to simulate the mid-Pliocene warm period (mPWP), 3.3–3.0 million years ago. We use MIROC4m, a fully coupled atmosphere-ocean general circulation model (AOGCM), and its atmospheric component alone to simulate the mPWP, utilizing up-to-date data sets designated in PlioMIP as boundary conditions and adhering to the protocols outlined. In this paper, a brief description of the model is given, followed by an explanation of the experimental design and implementation of the boundary conditions, such as topography and sea surface temperature. Initial results show increases of approximately 10°C in the zonal mean surface air temperature at high latitudes accompanied by a decrease in the equator-to-pole temperature gradient. Temperatures in the tropical regions increase more in the AOGCM. However, warming of the AOGCM sea surface in parts of the northern North Atlantic Ocean and Nordic Seas is less than that suggested by proxy data. An investigation of the model-data discrepancies and further model intercomparison studies can lead to a better understanding of the mid-Pliocene climate and of its role in assessing future climate change.

scholarly journals Tracking Scheme Dependence of Simulated Tropical Cyclone Response to Idealized Climate Simulations

2014 ◽  
Vol 27 (24) ◽  
pp. 9197-9213 ◽  
Author(s):  
Michael Horn ◽  
Kevin Walsh ◽  
Ming Zhao ◽  
Suzana J. Camargo ◽  
Enrico Scoccimarro ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
General Circulation Models ◽  
Tropical Cyclone Activity ◽  
Model Data ◽  
Cyclone Activity ◽  
Sensitivity Testing

Abstract Future tropical cyclone activity is a topic of great scientific and societal interest. In the absence of a climate theory of tropical cyclogenesis, general circulation models are the primary tool available for investigating the issue. However, the identification of tropical cyclones in model data at moderate resolution is complex, and numerous schemes have been developed for their detection. The influence of different tracking schemes on detected tropical cyclone activity and responses in the Hurricane Working Group experiments is examined herein. These are idealized atmospheric general circulation model experiments aimed at determining and distinguishing the effects of increased sea surface temperature and other increased CO2 effects on tropical cyclone activity. Two tracking schemes are applied to these data and the tracks provided by each modeling group are analyzed. The results herein indicate moderate agreement between the different tracking methods, with some models and experiments showing better agreement across schemes than others. When comparing responses between experiments, it is found that much of the disagreement between schemes is due to differences in duration, wind speed, and formation-latitude thresholds. After homogenization in these thresholds, agreement between different tracking methods is improved. However, much disagreement remains, accountable for by more fundamental differences between the tracking schemes. The results indicate that sensitivity testing and selection of objective thresholds are the key factors in obtaining meaningful, reproducible results when tracking tropical cyclones in climate model data at these resolutions, but that more fundamental differences between tracking methods can also have a significant impact on the responses in activity detected.

Changes in the Extratropical Storm Tracks in Response to Changes in SST in an AGCM

2012 ◽  
Vol 25 (6) ◽  
pp. 1854-1870 ◽  
Author(s):  
Lise Seland Graff ◽  
J. H. LaCasce
Keyword(s):  
Boundary Conditions ◽  
General Circulation ◽  
Lower Boundary ◽  
Storm Track ◽  
Circulation Model ◽  
Hadley Circulation ◽  
Meridional Overturning Circulation ◽  
Storm Tracks ◽  
Poleward Shift ◽  
The Mean

Abstract A poleward shift in the extratropical storm tracks has been identified in observational and climate simulations. The authors examine the role of altered sea surface temperatures (SSTs) on the storm-track position and intensity in an atmospheric general circulation model (AGCM) using realistic lower boundary conditions. A set of experiments was conducted in which the SSTs where changed by 2 K in specified latitude bands. The primary profile was inspired by the observed trend in ocean temperatures, with the largest warming occurring at low latitudes. The response to several other heating patterns was also investigated, to examine the effect of imposed gradients and low- versus high-latitude heating. The focus is on the Northern Hemisphere (NH) winter, averaged over a 20-yr period. Results show that the storm tracks respond to changes in both the mean SST and SST gradients, consistent with previous studies employing aquaplanet (water only) boundary conditions. Increasing the mean SST strengthens the Hadley circulation and the subtropical jets, causing the storm tracks to intensify and shift poleward. Increasing the SST gradient at midlatitudes similarly causes an intensification and a poleward shift of the storm tracks. Increasing the gradient in the tropics, on the other hand, causes the Hadley cells to contract and the storm tracks to shift equatorward. Consistent shifts are seen in the mean zonal velocity, the atmospheric baroclinicity, the eddy heat and momentum fluxes, and the atmospheric meridional overturning circulation. The results support the idea that oceanic heating could be a contributing factor to the observed shift in the storm tracks.

scholarly journals Applying an isotope-enabled regional climate model over the Greenland ice sheet: effect of spatial resolution on model bias

2021 ◽  
Vol 17 (4) ◽  
pp. 1685-1699
Author(s):  
Marcus Breil ◽  
Emanuel Christner ◽  
Alexandre Cauquoin ◽  
Martin Werner ◽  
Melanie Karremann ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
General Circulation ◽  
Climate Model ◽  
Regional Climate ◽  
Circulation Model ◽  
Ice Cores ◽  
Arctic Region ◽  
The Arctic ◽  
Simulation Results ◽  
The Arctic Region

Abstract. In order to investigate the impact of spatial resolution on the discrepancy between simulated δ18O and observed δ18O in Greenland ice cores, regional climate simulations are performed with the isotope-enabled regional climate model (RCM) COSMO_iso. For this purpose, isotope-enabled general circulation model (GCM) simulations with the ECHAM5-wiso general circulation model (GCM) under present-day conditions and the MPI-ESM-wiso GCM under mid-Holocene conditions are dynamically downscaled with COSMO_iso for the Arctic region. The capability of COSMO_iso to reproduce observed isotopic ratios in Greenland ice cores for these two periods is investigated by comparing the simulation results to measured δ18O ratios from snow pit samples, Global Network of Isotopes in Precipitation (GNIP) stations and ice cores. To our knowledge, this is the first time that a mid-Holocene isotope-enabled RCM simulation is performed for the Arctic region. Under present-day conditions, a dynamical downscaling of ECHAM5-wiso (1.1∘×1.1∘) with COSMO_iso to a spatial resolution of 50 km improves the agreement with the measured δ18O ratios for 14 of 19 observational data sets. A further increase in the spatial resolution to 7 km does not yield substantial improvements except for the coastal areas with its complex terrain. For the mid-Holocene, a fully coupled MPI-ESM-wiso time slice simulation is downscaled with COSMO_iso to a spatial resolution of 50 km. In the mid-Holocene, MPI-ESM-wiso already agrees well with observations in Greenland and a downscaling with COSMO_iso does not further improve the model–data agreement. Despite this lack of improvement in model biases, the study shows that in both periods, observed δ18O values at measurement sites constitute isotope ratios which are mainly within the subgrid-scale variability of the global ECHAM5-wiso and MPI-ESM-wiso simulation results. The correct δ18O ratios are consequently not resolved in the GCM simulation results and need to be extracted by a refinement with an RCM. In this context, the RCM simulations provide a spatial δ18O distribution by which the effects of local uncertainties can be taken into account in the comparison between point measurements and model outputs. Thus, an isotope-enabled GCM–RCM model chain with realistically implemented fractionating processes constitutes a useful supplement to reconstruct regional paleo-climate conditions during the mid-Holocene in Greenland. Such model chains might also be applied to reveal the full potential of GCMs in other regions and climate periods, in which large deviations relative to observed isotope ratios are simulated.

scholarly journals Modelling the impacts of climate change on tropospheric ozone over three centuries

2011 ◽  
Vol 11 (2) ◽  
pp. 6805-6843 ◽  
Author(s):  
G. B. Hedegaard ◽  
A. Gross ◽  
J. H. Christensen ◽  
W. May ◽  
H. Skov ◽  
...  
Keyword(s):  
Climate Change ◽  
Ozone Concentration ◽  
General Circulation ◽  
Climate Model ◽  
Transport Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
The Arctic

Abstract. The ozone chemistry over three centuries has been simulated based on climate prediction from a global climate model and constant anthropogenic emissions in order to separate out the effects on air pollution from climate change. Four decades in different centuries has been simulated using the chemistry version of the atmospheric long-range transport model; the Danish Eulerian Hemispheric Model (DEHM) forced with meteorology predicted by the ECHAM5/MPI-OM coupled Atmosphere-Ocean General Circulation Model. The largest changes in both meteorology, ozone and its precursors is found in the 21st century, however, also significant changes are found in the 22nd century. At surface level the ozone concentration is predicted to increase due to climate change in the areas where substantial amounts of ozone precursors are emitted. Elsewhere a significant decrease is predicted at the surface. In the free troposphere a general increase is found in the entire Northern Hemisphere except in the tropics, where the ozone concentration is decreasing. In the Arctic the ozone concentration will increase in the entire air column, which most likely is due to changes in transport. The change in temperature, humidity and the naturally emitted Volatile Organic Compounds (VOCs) are governing with respect to changes in ozone both in the past, present and future century.

scholarly journals A hybrid GCM paleo ice-sheet model, ANICE2.1 – [email protected]: set up and benchmark experiments

2018 ◽  
Author(s):  
Constantijn J. Berends ◽  
Bas de Boer ◽  
Roderik S. W. van de Wal
Keyword(s):  
Sea Level ◽  
General Circulation ◽  
Climate Model ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Circulation Model ◽  
Climate Modelling ◽  
Last Glacial ◽  
Model Set ◽  
Set Up

Abstract. Fully coupled ice-sheet-climate modelling over 10,000–100,000-year time scales on high spatial and temporal resolution remains beyond the capability of current computational systems. Hybrid GCM-ice-sheet modelling offers a middle ground, balancing the need to accurately capture both long-term processes, in particular circulation driven changes in precipitation, and processes requiring a high spatial resolution like ablation. Here, we present and evaluate a model set-up that forces the ANICE 3D thermodynamic ice-sheet-shelf model calculating all ice on Earth, with pre-calculated output from several steady-state simulations with the HadCM3 general circulation model (GCM), using a so-called matrix method of coupling both components, where simulations with various levels of pCO2 and ice-sheet configuration are combined to form a time-continuous transient climate forcing consistent with the modelled ice-sheets. We address the difficulties in downscaling low-resolution GCM output to the higher-resolution grid of an ice-sheet model, and account for differences between GCM and ice-sheet model surface topography ranging from interglacial to glacial conditions. As a benchmark experiment to assess the validity of this model set-up, we perform a simulation of the entire last glacial cycle, from 120 kyr ago to present-day. The simulated eustatic sea-level drop at the Last Glacial maximum (LGM) for the combined Antarctic, Greenland, Eurasian and North-American ice-sheets amounts to 100 m, in line with many other studies. The simulated ice-sheets at LGM agree well with the ICE-5G reconstruction and the more recent DATED-1 reconstruction in terms of total volume and geographical location of the ice sheets. Moreover, modelled benthic oxygen isotope abundance and the relative contributions from global ice volume and deep-water temperature agree well with available data, as do surface temperature histories for the Greenland and Antarctic ice-sheets. This model strategy can be used to create time-continuous ice-sheet distribution and sea-level reconstructions for geological periods up to several millions of years in duration, capturing climate model driven variations in the mass balance of the ice sheet.

scholarly journals Relations between Northward Ocean and Atmosphere Energy Transports in a Coupled Climate Model

2008 ◽  
Vol 21 (3) ◽  
pp. 561-575 ◽  
Author(s):  
Michael Vellinga ◽  
Peili Wu
Keyword(s):  
Heat Transport ◽  
General Circulation ◽  
Energy Transport ◽  
Climate Model ◽  
Atmospheric Transport ◽  
Circulation Model ◽  
Meridional Overturning Circulation ◽  
Ocean Heat Transport ◽  
Poleward Heat Transport ◽  
Low Latitudes

Abstract The Third Hadley Centre Coupled Ocean–Atmosphere General Circulation Model (HadCM3) is used to analyze the relation between northward energy transports in the ocean and atmosphere at centennial time scales. In a transient water-hosing experiment, where suppressing the Atlantic meridional overturning circulation (MOC) causes a reduction in northward ocean heat transport of up to 0.75 PW (i.e., 75%), the atmosphere compensates by increasing its northward transport of moist static energy. This compensation is very efficient at low latitudes and near complete at the equator throughout the experiment, but is incomplete farther north across the northern midlatitude storm tracks. The change in atmosphere energy transport enables the model to find a new global-mean radiative equilibrium after 240 yr. In a perturbed physics ensemble of HadCM3 it was found that time-averaged meridional energy transports in ocean and atmosphere can act opposingly. Where model formulation causes an unbalanced mean climate state, for example, an excessive top-of-the-atmosphere radiative surplus at low latitudes, the atmosphere increases its poleward energy transport to disperse this excess. MOC and ocean poleward heat transport tend to be reduced in such model versions, and this offsets the increased poleward atmospheric transport of the low-latitude energy surplus. Model versions that are close to net radiative equilibrium also have ocean heat transport and MOC close to observed values.

scholarly journals Sensitivity of Pliocene climate simulations in MRI-CGCM2.3 to respective boundary conditions

2016 ◽  
Vol 12 (8) ◽  
pp. 1619-1634 ◽  
Author(s):  
Youichi Kamae ◽  
Kohei Yoshida ◽  
Hiroaki Ueda
Keyword(s):  
Boundary Conditions ◽  
General Circulation ◽  
Model Comparison ◽  
Climate Model ◽  
Phase 1 ◽  
Regional Climate ◽  
Circulation Model ◽  
Poleward Heat Transport ◽  
Climate Simulations ◽  
Intercomparison Project

Abstract. Accumulations of global proxy data are essential steps for improving reliability of climate model simulations for the Pliocene warming climate. In the Pliocene Model Intercomparison Project phase 2 (PlioMIP2), a part project of the Paleoclimate Modelling Intercomparison Project phase 4, boundary forcing data have been updated from the PlioMIP phase 1 due to recent advances in understanding of oceanic, terrestrial and cryospheric aspects of the Pliocene palaeoenvironment. In this study, sensitivities of Pliocene climate simulations to the newly archived boundary conditions are evaluated by a set of simulations using an atmosphere–ocean coupled general circulation model, MRI-CGCM2.3. The simulated Pliocene climate is warmer than pre-industrial conditions for 2.4 °C in global mean, corresponding to 0.6 °C warmer than the PlioMIP1 simulation by the identical climate model. Revised orography, lakes, and shrunk ice sheets compared with the PlioMIP1 lead to local and remote influences including snow and sea ice albedo feedback, and poleward heat transport due to the atmosphere and ocean that result in additional warming over middle and high latitudes. The amplified higher-latitude warming is supported qualitatively by the proxy evidences, but is still underestimated quantitatively. Physical processes responsible for the global and regional climate changes should be further addressed in future studies under systematic intermodel and data–model comparison frameworks.

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