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 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 Intermodel Variability and Mechanism Attribution of Central and Southeastern U.S. Anomalous Cooling in the Twentieth Century as Simulated by CMIP5 Models

2013 ◽  
Vol 26 (17) ◽  
pp. 6215-6237 ◽  
Author(s):  
Zaitao Pan ◽  
Xiaodong Liu ◽  
Sanjiv Kumar ◽  
Zhiqiu Gao ◽  
James Kinter
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Land Surface ◽  
Regional Scale ◽  
Coupled Model ◽  
The United States ◽  
Cmip5 Models ◽  
Model Intercomparison ◽  
Central United States ◽  
Intercomparison Project

Abstract Some parts of the United States, especially the southeastern and central portion, cooled by up to 2°C during the twentieth century, while the global mean temperature rose by 0.6°C (0.76°C from 1901 to 2006). Studies have suggested that the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO) may be responsible for this cooling, termed the “warming hole” (WH), while other works reported that regional-scale processes such as the low-level jet and evapotranspiration contribute to the abnormity. In phase 3 of the Coupled Model Intercomparison Project (CMIP3), only a few of the 53 simulations could reproduce the cooling. This study analyzes newly available simulations in experiments from phase 5 of the Coupled Model Intercomparison Project (CMIP5) from 28 models, totaling 175 ensemble members. It was found that 1) only 19 out of 100 all-forcing historical ensemble members simulated negative temperature trend (cooling) over the southeast United States, with 99 members underpredicting the cooling rate in the region; 2) the missing of cooling in the models is likely due to the poor performance in simulating the spatial pattern of the cooling rather than the temporal variation, as indicated by a larger temporal correlation coefficient than spatial one between the observation and simulations; 3) the simulations with greenhouse gas (GHG) forcing only produced strong warming in the central United States that may have compensated the cooling; and 4) the all-forcing historical experiment compared with the natural-forcing-only experiment showed a well-defined WH in the central United States, suggesting that land surface processes, among others, could have contributed to the cooling in the twentieth century.

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 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.

Evaluation of the tail of the probability distribution of daily and sub-daily precipitation in CMIP6 models

2021 ◽  
pp. 1-61
Author(s):  
Jesse Norris ◽  
Alex Hall ◽  
J. David Neelin ◽  
Chad W. Thackeray ◽  
Di Chen
Keyword(s):  
General Circulation ◽  
Daily Precipitation ◽  
Precipitation Amount ◽  
Coupled Model ◽  
Lower Troposphere ◽  
General Circulation Models ◽  
Intercomparison Project ◽  
Cloud Tops ◽  
The Tropics ◽  
Fraction Models

AbstractDaily and sub-daily precipitation extremes in historical Coupled-Model-Intercomparison-Project-Phase-6 (CMIP6) simulations are evaluated against satellite-based observational estimates. Extremes are defined as the precipitation amount exceeded every x years, ranging from 0.01–10, encompassing the rarest events that are detectable in the observational record without noisy results. With increasing temporal resolution there is an increased discrepancy between models and observations: for daily extremes the multi-model median underestimates the highest percentiles by about a third, and for 3-hourly extremes by about 75% in the tropics. The novelty of the current study is that, to understand the model spread, we evaluate the 3-D structure of the atmosphere when extremes occur. In midlatitudes, where extremes are simulated predominantly explicitly, the intuitive relationship exists whereby higher-resolution models produce larger extremes (r=–0.49), via greater vertical velocity. In the tropics, the convective fraction (the fraction of precipitation simulated directly from the convective scheme) is more relevant. For models below 60% convective fraction, precipitation amount decreases with convective fraction (r=–0.63), but above 75% convective fraction, this relationship breaks down. In the lower-convective-fraction models, there is more moisture in the lower troposphere, closer to saturation. In the higher-convective-fraction models, there is deeper convection and higher cloud tops, which appears to be more physical. Thus, the low-convective models are mostly closer to the observations of extreme precipitation in the tropics, but likely for the wrong reasons. These inter-model differences in the environment in which extremes are simulated hold clues into how parameterizations could be modified in general circulation models to produce more credible 21st-Century projections.

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 Summer U.S. Surface Air Temperature Variability: Controlling Factors and AMIP Simulation Biases

2016 ◽  
Vol 29 (14) ◽  
pp. 5123-5139 ◽  
Author(s):  
Anna L. Merrifield ◽  
Shang-Ping Xie
Keyword(s):  
United States ◽  
Heat Flux ◽  
Land Surface ◽  
Sensible Heat Flux ◽  
Surface Air Temperature ◽  
Sensible Heat ◽  
Model Intercomparison ◽  
Central United States ◽  
Intercomparison Project ◽  
Atmosphere Interaction

Abstract This study documents and investigates biases in simulating summer surface air temperature (SAT) variability over the continental United States in the Atmospheric Model Intercomparison Project (AMIP) experiment from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Empirical orthogonal function (EOF) and multivariate regression analyses are used to assess the relative importance of circulation and the land surface feedback at setting summer SAT over a 30-yr period (1979–2008). Regions of high SAT variability are closely associated with midtropospheric highs, subsidence, and radiative heating accompanying clear-sky conditions. The land surface exerts a spatially variable influence on SAT through the sensible heat flux and is a second-order effect in the high-variability centers of action (COAs) in observational estimates. The majority of the AMIP models feature high SAT variability over the central United States, displaced south and/or west of observed COAs. SAT COAs in models tend to be concomitant and strongly coupled with regions of high sensible heat flux variability, suggesting that excessive land–atmosphere interaction in these models modulates U.S. summer SAT. In the central United States, models with climatological warm biases also feature less evapotranspiration than ERA-Interim but reasonably reproduce observed SAT variability in the region. Models that overestimate SAT variability tend to reproduce ERA-Interim SAT and evapotranspiration climatology. In light of potential model biases, this analysis calls for careful evaluation of the land–atmosphere interaction hot spot region identified in the central United States. Additionally, tropical sea surface temperatures play a role in forcing the leading EOF mode for summer SAT in models. This relationship is not apparent in observations.

scholarly journals Climate and African precipitation changes in the mid-Holocene simulated using an Earth System Model MIROC-ESM

2012 ◽  
Vol 8 (4) ◽  
pp. 3277-3343 ◽  
Author(s):  
R. Ohgaito ◽  
T. Sueyoshi ◽  
A. Abe-Ouchi ◽  
T. Hajima ◽  
S. Watanabe ◽  
...  
Keyword(s):  
General Circulation ◽  
Coupled Model ◽  
Circulation Model ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
African Monsoon ◽  
Proxy Records ◽  
Intercomparison Project ◽  
Precipitation Changes

Abstract. The importance of evaluating models using paleoclimate simulations is becoming more recognized in efforts to improve climate projection. To evaluate an integrated Earth System Model, MIROC-ESM, we performed simulations in time-slice experiments for the mid-Holocene (6000 yr before present, 6 ka) and preindustrial (1850 AD) times under the protocol of the Coupled Model Intercomparison Project 5/Paleoclimate Modelling Intercomparison Project 3. We first overview the simulated global climates by comparing with simulations using a previous version of the MIROC model (MIROC3), which is an atmosphere-ocean coupled general circulation model, and then comprehensively discuss various aspects of climate change with 6 ka forcing. We also discuss the 6 ka African monsoon activity. The 6 ka precipitation change over northern Africa according to MIROC-ESM does not differ dramatically from that obtained with MIROC3, which means that newly developed components such as dynamic vegetation and improvements in the atmospheric processes do not have significant impacts on representing the 6 ka monsoon change suggested by proxy records. Although there is no drastic difference in the African monsoon representation between the two models, there are small but significant differences in the precipitation enhancement in MIROC-ESM, which can be related to the representation of the sea surface temperature rather than the vegetation coupling, at least in MIROC-ESM.

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