scholarly journals Variable resolution general circulation models: Stretched-grid model intercomparison project (SGMIP)

2006 ◽  
Vol 111 (D16) ◽  
Author(s):  
Michael Fox-Rabinovitz ◽  
Jean Côté ◽  
Bernard Dugas ◽  
Michel Déqué ◽  
John L. McGregor
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Model Intercomparison ◽  
Variable Resolution ◽  
Grid Model ◽  
Intercomparison Project

scholarly journals The Tibetan Plateau Summer Monsoon in the CMIP5 Simulations

2013 ◽  
Vol 26 (19) ◽  
pp. 7747-7766 ◽  
Author(s):  
Anmin Duan ◽  
Jun Hu ◽  
Zhixiang Xiao
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
General Circulation ◽  
General Circulation Models ◽  
Surface Heat ◽  
The Tibetan Plateau ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
Asian Summer ◽  
Heat Low

Abstract Temporal variability within the Tibetan Plateau summer monsoon (TPSM) is closely linked to both the East and South Asian summer monsoons over several time scales but has received much less attention than these other systems. In this study, extensive integrations under phase 5 of the Coupled Model Intercomparison Project (CMIP5) historical scenarios from 15 coupled general circulation models (CGCMs) and Atmospheric Model Intercomparison Project (AMIP) runs from eight atmospheric general circulation models (AGCMs) are used to evaluate the performance of these GCMs. Results indicate that all GCMs are able to simulate the climate mean TPSM circulation system. However, the large bias associated with precipitation intensity and patterns remains, despite the higher resolution and inclusion of the indirect effects of sulfate aerosol that have helped to improve the skill of the models to simulate the annual cycle of precipitation in both AGCMs and CGCMs. The interannual variability of the surface heat low and the Tibetan high in most of the AGCMs resembles the observation reasonably because of the prescribed forcing fields. However, only a few models were able to reproduce the observed seesaw pattern associated with the interannual variability of the TPSM and the East Asian summer monsoon (EASM). Regarding long-term trends, most models overestimated the amplitude of the tropospheric warming and the declining trend in the surface heat low between 1979 and 2005. In addition, the observed cooling trend in the upper troposphere and the decline of the Tibetan high were not reproduced by most models. Therefore, there is still significant scope for improving GCM simulations of regional climate change, especially in regions near extensive mountain ranges.

scholarly journals Bias-corrected climate projections for South Asia from Coupled Model Intercomparison Project-6

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Vimal Mishra ◽  
Udit Bhatia ◽  
Amar Deep Tiwari
Keyword(s):  
Climate Change ◽  
Impact Assessment ◽  
South Asia ◽  
General Circulation ◽  
Coupled Model ◽  
General Circulation Models ◽  
River Basins ◽  
Climate Projections ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract Climate change is likely to pose enormous challenges for agriculture, water resources, infrastructure, and livelihood of millions of people living in South Asia. Here, we develop daily bias-corrected data of precipitation, maximum and minimum temperatures at 0.25° spatial resolution for South Asia (India, Pakistan, Bangladesh, Nepal, Bhutan, and Sri Lanka) and 18 river basins located in the Indian sub-continent. The bias-corrected dataset is developed using Empirical Quantile Mapping (EQM) for the historic (1951–2014) and projected (2015–2100) climate for the four scenarios (SSP126, SSP245, SSP370, SSP585) using output from 13 General Circulation Models (GCMs) from Coupled Model Intercomparison Project-6 (CMIP6). The bias-corrected dataset was evaluated against the observations for both mean and extremes of precipitation, maximum and minimum temperatures. Bias corrected projections from 13 CMIP6-GCMs project a warmer (3–5°C) and wetter (13–30%) climate in South Asia in the 21st century. The bias-corrected projections from CMIP6-GCMs can be used for climate change impact assessment in South Asia and hydrologic impact assessment in the sub-continental river basins.

scholarly journals Modifying emissions scenario projections to account for the effects of COVID-19: protocol for CovidMIP

2021 ◽  
Vol 14 (6) ◽  
pp. 3683-3695
Author(s):  
Robin D. Lamboll ◽  
Chris D. Jones ◽  
Ragnhild B. Skeie ◽  
Stephanie Fiedler ◽  
Bjørn H. Samset ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
General Circulation ◽  
General Circulation Models ◽  
Activity Levels ◽  
Model Intercomparison ◽  
Country Level ◽  
Detection And Attribution ◽  
Intercomparison Project ◽  
Level Scale ◽  
The Impact

Abstract. Lockdowns to avoid the spread of COVID-19 have created an unprecedented reduction in human emissions. While the country-level scale of emissions changes can be estimated in near real time, the more detailed, gridded emissions estimates that are required to run general circulation models (GCMs) of the climate will take longer to collect. In this paper we use recorded and projected country-and-sector activity levels to modify gridded predictions from the MESSAGE-GLOBIOM SSP2-4.5 scenario. We provide updated projections for concentrations of greenhouse gases, emissions fields for aerosols, and precursors and the ozone and optical properties that result from this. The code base to perform similar modifications to other scenarios is also provided. We outline the means by which these results may be used in a model intercomparison project (CovidMIP) to investigate the impact of national lockdown measures on climate, including regional temperature, precipitation, and circulation changes. This includes three strands: an assessment of short-term effects (5-year period) and of longer-term effects (30 years) and an investigation into the separate effects of changes in emissions of greenhouse gases and aerosols. This last strand supports the possible attribution of observed changes in the climate system; hence these simulations will also form part of the Detection and Attribution Model Intercomparison Project (DAMIP).

scholarly journals Radiative-Convective Equilibrium Model Intercomparison Project

2017 ◽  
Author(s):  
Allison A. Wing ◽  
Kevin A. Reed ◽  
Masaki Satoh ◽  
Bjorn Stevens ◽  
Sandrine Bony ◽  
...  
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Cloud Fraction ◽  
Model Intercomparison ◽  
Tropical Circulation ◽  
Cloud Feedbacks ◽  
Single Column ◽  
Intercomparison Project ◽  
Self Aggregation

Abstract. RCEMIP, an intercomparison of multiple types of models configured in radiative-convective equilibrium (RCE), is proposed. RCE is an idealization of the climate system in which there is a balance between radiative cooling of the atmosphere and heating by convection. The scientific objectives of RCEMIP are three-fold. First, clouds and climate sensitivity will be investigated in the RCE setting. This includes determining how cloud fraction changes with warming and the role of self-aggregation of convection. Second, RCEMIP will quantify the dependence of the degree of convective aggregation and tropical circulation regimes on temperature. Finally, by providing a common baseline, RCEMIP will allow the robustness of the RCE state, cloud feedbacks, and convective aggregation across the spectrum of models to be assessed. A novel aspect and major advantage of RCEMIP is the accessibility of the RCE framework to a variety of models, including cloud-resolving models, general circulation models, global cloud-resolving models, and single column models.

scholarly journals An Assessment of Future Southern Hemisphere Blocking Using CMIP5 Projections from Four GCMs

2016 ◽  
Vol 29 (21) ◽  
pp. 7599-7611 ◽  
Author(s):  
Simon Parsons ◽  
James A. Renwick ◽  
Adrian J. McDonald
Keyword(s):  
Southern Hemisphere ◽  
General Circulation ◽  
Coupled Model ◽  
General Circulation Models ◽  
Southern Annular Mode ◽  
Model Intercomparison ◽  
Future Projections ◽  
South Pacific Ocean ◽  
Blocking Activity ◽  
Intercomparison Project

AbstractThis study is concerned with blocking events (BEs) in the Southern Hemisphere (SH), their past variability, and future projections. ERA-Interim (ERA-I) is used to compare the historical output from four general circulation models (GCMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5); the output of the representative concentration pathway 4.5 and 8.5 (RCP4.5 and RCP8.5) projections are also examined. ERA-I shows that the higher latitudes of the South Pacific Ocean (SPO) are the main blocking region, with blocking occurring predominantly in winter. The CMIP5 historical simulations also agree well with ERA-I for annual and seasonal BE locations and frequencies. A reduction in BEs is observed in the SPO in the 2071–2100 period in the RCP4.5 projections, and this is more pronounced for the RCP8.5 projections and occurs predominantly during the spring and summer seasons. Preliminary investigations imply that the southern annular mode (SAM) is negatively correlated with blocking activity in the SPO in all seasons in the reanalysis. This negative correlation is also observed in the GCM historical output. However, in the RCP projections this correlation is reduced in three of the four models during summer, suggesting that SAM may be less influential in summertime blocking in the future.

scholarly journals GCM Simulations of the Climate in the Central United States

2005 ◽  
Vol 18 (7) ◽  
pp. 1016-1031 ◽  
Author(s):  
Kenneth E. Kunkel ◽  
Xin-Zhong Liang
Keyword(s):  
United States ◽  
General Circulation ◽  
Coupled Model ◽  
Scalar Fields ◽  
General Circulation Models ◽  
Atmospheric Model ◽  
Model Intercomparison ◽  
Central United States ◽  
Intercomparison Project ◽  
Precipitation Changes

Abstract A diagnostic analysis of relationships between central U.S. climate characteristics and various flow and scalar fields was used to evaluate nine global coupled ocean–atmosphere general circulation models (CGCMs) participating in the Coupled Model Intercomparison Project (CMIP). To facilitate identification of physical mechanisms causing biases, data from 21 models participating in the Atmospheric Model Intercomparison Project (AMIP) were also used for certain key analyses. Most models reproduce basic features of the circulation, temperature, and precipitation patterns in the central United States, although no model exhibits small differences from the observationally based data for all characteristics in all seasons. Model ensemble means generally produce better agreement with the observationally based data than any single model. A fall precipitation deficiency, found in all AMIP and CMIP models except the third-generation Hadley Centre CGCM (HadCM3), appears to be related in part to slight biases in the flow on the western flank of the Atlantic subtropical ridge. In the model mean, the ridge at 850 hPa is displaced slightly to the north and to the west, resulting in weaker southerly flow into the central United States. The CMIP doubled-CO2 transient runs show warming (1°–5°C) for all models and seasons and variable precipitation changes over the central United States. Temperature (precipitation) changes are larger (mostly less) than the variations that are observed in the twentieth century and the model variations in the control simulations.

scholarly journals Evaluating and improving the treatment of gases in radiation schemes: the Correlated K-Distribution Model Intercomparison Project (CKDMIP)

2020 ◽  
Author(s):  
Robin J. Hogan ◽  
Marco Matricardi
Keyword(s):  
General Circulation ◽  
Computational Cost ◽  
General Circulation Models ◽  
Gas Absorption ◽  
Distribution Model ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Climate Modelling ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract. Most radiation schemes in weather and climate models use the 'correlated k-distribution' (CKD) method to treat gas absorption, which approximates a broadband spectral integration by N pseudo-monochromatic calculations. Larger N means more accuracy and a wider range of gas concentrations can be simulated, but at greater computational cost. Unfortunately, the tools to perform this efficiency-accuracy trade-off (e.g., to generate separate CKD models for applications such as short-range weather forecasting to climate modelling) are unavailable to the vast majority of users of radiation schemes. This paper describes the experimental protocol for the Correlated K-Distribution Model Intercomparison Project (CKDMIP), whose purpose is to use benchmark line-by-line calculations: (1) to evaluate the accuracy of existing CKD models, (2) to explore how accuracy varies with N for CKD models submitted by CKDMIP participants, (3) to understand how different choices in way that CKD models are generated affects their accuracy for the same N, and (4) to generate freely available datasets and software facilitating the development of new gas-optics tools. The datasets consist of the high-resolution longwave and shortwave absorption spectra of nine gases for a range of atmospheric conditions, realistic and idealized. Thirty-four concentration scenarios for the well-mixed greenhouse gases are proposed to test CKD models from palaeo- to future-climate conditions. We demonstrate the strengths of the protocol in this paper by using it to evaluate the widely-used Rapid Radiative Transfer Model for General Circulation Models (RRTMG).

scholarly journals A Canadian Contribution to the Paleoclimate Model Intercomparison Project (PMIP)

2007 ◽  
Vol 49 (1) ◽  
pp. 4-12 ◽  
Author(s):  
Hélène Jetté
Keyword(s):  
General Circulation ◽  
Scientific Community ◽  
General Circulation Models ◽  
Climatic Conditions ◽  
Sea Surface ◽  
Laurentide Ice Sheet ◽  
Model Intercomparison ◽  
Wide Range ◽  
Intercomparison Project ◽  
Study Sites

ABSTRACT PMIP (Paleoclimate Model lntercomparison Project) is designed to compare and improve the ability of General Circulation Models (GCMs) to simulate a wide range of climatic conditions including known features of past climatic states that are significantly different from present conditions. One of the first simulations of past climate conducted under this project targets the 6000 yr BP period for the following reasons: 1) deglaciation was complete and the last remnants of the Laurentide Ice Sheet had essentially disappeared by this time, 2) sea surface temperatures approached modern values, 3) the orbital insolation regime was the only major boundary condition significantly different from present, and 4) a number of study sites can already be used to provide preliminary paleoenvironmental reconstructions for this period. Contributions from the Canadian scientific community towards this experiment are presented, following a brief overview of Canadian modern environmental conditions which places the regional contributions into a broader perspective.

scholarly journals Tropical Biases in CMIP5 Multimodel Ensemble: The Excessive Equatorial Pacific Cold Tongue and Double ITCZ Problems*

2014 ◽  
Vol 27 (4) ◽  
pp. 1765-1780 ◽  
Author(s):  
Gen Li ◽  
Shang-Ping Xie
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Atmospheric Model ◽  
Equatorial Pacific ◽  
Cold Tongue ◽  
Model Intercomparison ◽  
Tropical Ocean ◽  
Easterly Wind ◽  
Double Itcz ◽  
Intercomparison Project

Abstract Errors of coupled general circulation models (CGCMs) limit their utility for climate prediction and projection. Origins of and feedback for tropical biases are investigated in the historical climate simulations of 18 CGCMs from phase 5 of the Coupled Model Intercomparison Project (CMIP5), together with the available Atmospheric Model Intercomparison Project (AMIP) simulations. Based on an intermodel empirical orthogonal function (EOF) analysis of tropical Pacific precipitation, the excessive equatorial Pacific cold tongue and double intertropical convergence zone (ITCZ) stand out as the most prominent errors of the current generation of CGCMs. The comparison of CMIP–AMIP pairs enables us to identify whether a given type of errors originates from atmospheric models. The equatorial Pacific cold tongue bias is associated with deficient precipitation and surface easterly wind biases in the western half of the basin in CGCMs, but these errors are absent in atmosphere-only models, indicating that the errors arise from the interaction with the ocean via Bjerknes feedback. For the double ITCZ problem, excessive precipitation south of the equator correlates well with excessive downward solar radiation in the Southern Hemisphere (SH) midlatitudes, an error traced back to atmospheric model simulations of cloud during austral spring and summer. This extratropical forcing of the ITCZ displacements is mediated by tropical ocean–atmosphere interaction and is consistent with recent studies of ocean–atmospheric energy transport balance.

scholarly journals Applicability of GCMs for evaluation of agro-climatic properties of local territories

2021 ◽  
pp. 23-30
Author(s):  
N.A. Lemeshko ◽  
◽  
V.P. Evstigneev ◽  
A.P. Morozov ◽  
V.A. Rusakov ◽  
...  
Keyword(s):  
General Circulation ◽  
Coupled Model ◽  
General Circulation Models ◽  
Climatic Conditions ◽  
European Part ◽  
Model Intercomparison ◽  
Ocean Atmosphere ◽  
European Part Of Russia ◽  
Intercomparison Project ◽  
Statistical Criteria

The analysis of reliability and accuracy reproduction of air temperature, precipitation, and relative humidity of the air by 18 ocean-atmosphere general circulation models (GCMs) included in CMIP6 (Coupled Model Intercomparison Project) is performed. Based on statistical criteria, the best models that most accurately reproduce empirical data are selected. On the basis of these models, an ensemble of models is compiled. The calculation of several agro-climatic indicators for the European part of Russia is performed using an ensemble approach. The comparison of agro-climatic indicators calculated on the basis of the ensemble of models and observational data is carried out for the territory of the Upper Volga including Yaroslavl, Kostroma, Vologda, Novgorod and Tver regions. The feasibility of using the ensemble of models to assess agro-climatic conditions of the region is shown.

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