scholarly journals Bayesian Design and Analysis for Superensemble-Based Climate Forecasting

2008 ◽  
Vol 21 (9) ◽  
pp. 1891-1910 ◽  
Author(s):  
L. Mark Berliner ◽  
Yongku Kim
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Climate Modeling ◽  
Climate System ◽  
System Model ◽  
Climate System Model ◽  
Bayesian Hierarchical ◽  
Climate Forecasting ◽  
Forecasting Analysis ◽  
States Of Nature

Abstract The authors develop statistical data models to combine ensembles from multiple climate models in a fashion that accounts for uncertainty. This formulation enables treatment of model specific means, biases, and covariance matrices of the ensembles. In addition, the authors model the uncertainty in using computer model results to estimate true states of nature. Based on these models and principles of decision making in the presence of uncertainty, this paper poses the problem of superensemble experimental design in a quantitative fashion. Simple examples of the resulting optimal designs are presented. The authors also provide a Bayesian climate modeling and forecasting analysis. The climate variables of interest are Northern and Southern Hemispheric monthly averaged surface temperatures. A Bayesian hierarchical model for these quantities is constructed, including time-varying parameters that are modeled as random variables with distributions depending in part on atmospheric CO2 levels. This allows the authors to do Bayesian forecasting of temperatures under different Special Report on Emissions Scenarios (SRES). These forecasts are based on Bayesian posterior distributions of the unknowns conditional on observational data for 1882–2001 and climate system model output for 2002–97. The latter dataset is a small superensemble from the Parallel Climate Model (PCM) and the Community Climate System Model (CCSM). After summarizing the results, the paper concludes with discussion of potential generalizations of the authors’ strategies.

scholarly journals Influence of parallel computational uncertainty on simulations of the Coupled General Climate Model

2012 ◽  
Vol 5 (2) ◽  
pp. 313-319 ◽  
Author(s):  
Z. Song ◽  
F. Qiao ◽  
X. Lei ◽  
C. Wang
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Quality Standard ◽  
Ensemble Member ◽  
Climate System ◽  
Climate System Model ◽  
Climate Simulations ◽  
Computational Uncertainty ◽  
The Impact ◽  
General Climate

Abstract. This paper investigates the impact of the parallel computational uncertainty due to the round-off error on climate simulations using the Community Climate System Model Version 3 (CCSM3). A series of sensitivity experiments have been conducted and the analyses are focused on the Global and Nino3.4 average sea surface temperatures (SST). For the monthly time series, it is shown that the amplitude of the deviation induced by the parallel computational uncertainty is the same order as that of the climate system change. However, the ensemble mean method can reduce the influence and the ensemble member number of 15 is enough to ignore the uncertainty. For climatology, the influence can be ignored when the climatological mean is calculated by using more than 30-yr simulations. It is also found that the parallel computational uncertainty has no distinguishable effect on power spectrum analysis of climate variability such as ENSO. Finally, it is suggested that the influence of the parallel computational uncertainty on Coupled General Climate Models (CGCMs) can be a quality standard or a metric for developing CGCMs.

scholarly journals Volcano impacts on climate and biogeochemistry in a coupled carbon-climate model

2012 ◽  
Vol 3 (1) ◽  
pp. 279-323 ◽  
Author(s):  
D. Rothenberg ◽  
N. Mahowald ◽  
K. Lindsay ◽  
S. C. Doney ◽  
J. K. Moore ◽  
...  
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Climate System ◽  
Dynamical Response ◽  
Good Test ◽  
Important Species ◽  
Climate System Model ◽  
Temperature And Precipitation ◽  
Wrong Reason

Abstract. Volcanic eruptions induce a dynamical response in the climate system characterized by short-term, global reductions in both surface temperature and precipitation, as well as a response in biogeochemistry. The available observations of these responses to volcanic eruptions, such as to Pinatubo, provide a valuable method to compare against model simulations. Here, the Community Climate System Model Version 3 (CCSM3) reproduces the physical climate response to volcanic eruptions in a realistic way, as compared to direct observations from the 1991 eruption of Mount Pinatubo. The model biogeochemical response to eruptions is smaller in magnitude than observed, but because of the lack observations, it is not clear why or where the modeled carbon response is not strong enough. Comparison to other models suggests that this model response is much weaker in the tropical land; however the precipitation response in other models is not accurate, suggesting that other models could be getting the right response for the wrong reason. The underestimated carbon response in the model compared to observations could also be due to the ash and lava input of biogeochemical important species to the ocean, which are not included in the simulation. A statistically significant reduction in the simulated carbon dioxide growth rate is seen at the 90% level in the average of 12 large eruptions over the period 1870–2000, and the net uptake of carbon is primarily concentrated in the tropics with large spatial variability. In addition, a method for computing the volcanic response in model output without using a control ensemble is tested against a traditional methodology using two separate ensembles of runs; the method is found to produce similar results. These results suggest that not only is simulating volcanoes a good test of coupled carbon-climate models, but also that this test can be performed without a control simulation in cases where it is not practical to run separate ensembles with and without volcanic eruptions.

scholarly journals Influence of parallel computational uncertainty on simulations of the Coupled General Climate Model

2011 ◽  
Vol 4 (4) ◽  
pp. 3295-3312
Author(s):  
Z. Song ◽  
F. Qiao ◽  
X. Lei ◽  
C. Wang
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Quality Standard ◽  
Ensemble Member ◽  
Climate System ◽  
Climate System Model ◽  
Climate Simulations ◽  
Computational Uncertainty ◽  
The Impact ◽  
General Climate

Abstract. This paper investigates the impact of the parallel computational uncertainty on climate simulations using the Community Climate System Model Version 3 (CCSM3). A series of sensitivity experiments have been conducted and the analyses are focused on the Global and Nino3.4 sea surface temperatures. It is shown that the amplitude of the deviation induced by the parallel computational uncertainty is the same order as that of the climate system change. However, the ensemble mean method can reduce the influence and the ensemble member number of 15 is enough to ignore simulated errors. For climatology, the influence can be ignored when the climatological mean is calculated by using more than 30-yr simulations. It is also found that the parallel computational uncertainty has no effect on the simulated periods of climate variability such as ENSO. Finally, it is suggested that the influence of the parallel computational uncertainty on Coupled General Climate Models (CGCMs) can be a quality standard or a metric for developing CGCMs.

scholarly journals Response to Increasing Southern Hemisphere Winds in CCSM4

2011 ◽  
Vol 24 (19) ◽  
pp. 4992-4998 ◽  
Author(s):  
Peter R. Gent ◽  
Gokhan Danabasoglu
Keyword(s):  
Southern Hemisphere ◽  
Variable Coefficient ◽  
Climate Models ◽  
Climate Model ◽  
System Model ◽  
Climate System Model ◽  
Coarse Resolution ◽  
Ocean Response ◽  
Ocean Models ◽  
Eddy Parameterization

Results from two perturbation experiments using the Community Climate System Model version 4 where the Southern Hemisphere zonal wind stress is increased are described. It is shown that the ocean response is in accord with experiments using much-higher-resolution ocean models that do not use an eddy parameterization. The key to obtaining an appropriate response in the coarse-resolution climate model is to specify a variable coefficient in the Gent and McWilliams eddy parameterization, rather than a constant value. This result contrasts with several recent papers that have suggested that coarse-resolution climate models cannot obtain an appropriate response.

scholarly journals Quantifying Agulhas Leakage in a High-Resolution Climate Model

2016 ◽  
Vol 29 (19) ◽  
pp. 6881-6892 ◽  
Author(s):  
Yu Cheng ◽  
Dian Putrasahan ◽  
Lisa Beal ◽  
Ben Kirtman
Keyword(s):  
Time Scales ◽  
Climate Models ◽  
Climate Model ◽  
Critical Role ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
Climate System Model ◽  
Mean Fields ◽  
Meridional Overturning ◽  
The Indian Ocean

Abstract The leakage of warm and salty water from the Indian Ocean via the Agulhas system into the South Atlantic may play a critical role in climate variability by modulating the buoyancy fluxes associated with the meridional overturning circulation (MOC). New climate models, such as the Community Climate System Model, version 3.5 (CCSM3.5), are now able to resolve the Agulhas retroflection and constrain the inertially choked Agulhas leakage to more realistic values. These ocean-eddy-resolving climate models are poised to bolster understanding of the sensitivity and influence of Agulhas leakage in the coupled climate system. Here, a strategy is devised to quantify Agulhas leakage in CCSM3.5 by applying an offline Lagrangian particle-tracking approach, finding a mean interbasin transport of 11.2 Sv (1 Sv ≡ 106 m3 s−1). It is shown that monthly mean outputs can be used to produce a reliable time series of Agulhas leakage variability on longer-than-seasonal time scales (correlation coefficient r = 0.88; p < 0.01) by comparing to a parallel simulation that archives daily mean fields every 5 days. The results show that Agulhas leakage variability at longer-than-seasonal time scales is less sensitive to the temporal resolution of the velocity fields than is the mean leakage transport.

scholarly journals A regional atmosphere-ocean climate system model (CCLMv5.0clm7-NEMOv3.3-NEMOv3.6) over Europe including three marginal seas: on its stability and performance

2019 ◽  
Author(s):  
Cristina Primo ◽  
Fanni D. Kelemen ◽  
Hendrik Feldmann ◽  
Bodo Ahrens
Keyword(s):  
20Th Century ◽  
Extreme Events ◽  
Climate Models ◽  
Regional Climate ◽  
Coupled System ◽  
Climate System ◽  
Added Value ◽  
System Model ◽  
Climate System Model ◽  
Marginal Seas

Abstract. The frequency of extreme events has changed, having a direct impact on human lives. Regional climate models help us to predict these regional climate changes. This work presents an atmosphere-ocean coupled regional climate system model (RCSM, with the atmospheric component COSMO-CLM and the ocean component NEMO) over the European domain, including three marginal seas: the Mediterranean, the North and the Baltic Seas. To test the model, we evaluate a simulation of more than one hundred years (1900–2009) with a spatial grid resolution of about 25 km. The simulation was nested into a coupled global simulation with the model MPI-ESM, whose ocean temperature and salinity was nudged to an MPI-ESM ocean-ice component forced with the 20th Century Reanalysis (20CR). The evaluation shows the robustness of the RCSM and discusses the added value by the coupled marginal seas over an atmosphere-only simulation. The coupled system runs stable for the complete 20th century and provides a better representation of extreme temperatures compared to the atmosphere-only model. The produced long-term dataset will allow an improved study of extreme events, helping us to better understand the processes leading to meteorological and climate extremes and their prediction.

scholarly journals Volcano impacts on climate and biogeochemistry in a coupled carbon–climate model

2012 ◽  
Vol 3 (2) ◽  
pp. 121-136 ◽  
Author(s):  
D. Rothenberg ◽  
N. Mahowald ◽  
K. Lindsay ◽  
S. C. Doney ◽  
J. K. Moore ◽  
...  
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Climate System ◽  
Dynamical Response ◽  
Good Test ◽  
Important Species ◽  
Climate System Model ◽  
Temperature And Precipitation ◽  
Wrong Reason

Abstract. Volcanic eruptions induce a dynamical response in the climate system characterized by short-term global reductions in both surface temperature and precipitation, as well as a response in biogeochemistry. The available observations of these responses to volcanic eruptions, such as to Pinatubo, provide a valuable method to compare against model simulations. Here, the Community Climate System Model Version 3 (CCSM3) reproduces the physical climate response to volcanic eruptions in a realistic way, as compared to direct observations from the 1991 eruption of Mount Pinatubo. The model's biogeochemical response to eruptions is smaller in magnitude than observed, but because of the lack of observations, it is not clear why or where the modeled carbon response is not strong enough. Comparison to other models suggests that this model response is much weaker over tropical land; however, the precipitation response in other models is not accurate, suggesting that other models could be getting the right response for the wrong reason. The underestimated carbon response in the model compared to observations could also be due to the ash and lava input of biogeochemically important species to the ocean, which are not included in the simulation. A statistically significant reduction in the simulated carbon dioxide growth rate is seen at the 90% level in the average of 12 large eruptions over the period 1870–2000, and the net uptake of carbon is primarily concentrated in the tropics, with large spatial variability. In addition, a method for computing the volcanic response in model output without using a control ensemble is tested against a traditional methodology using two separate ensembles of runs; the method is found to produce similar results in the global average. These results suggest that not only is simulating volcanoes a good test of coupled carbon–climate models, but also that this test can be performed without a control simulation in cases where it is not practical to run separate ensembles with and without volcanic eruptions.

scholarly journals A multivariate comparison of two land-surface models integrated into an Arctic Regional Climate System model

1997 ◽  
Vol 25 ◽  
pp. 127-131
Author(s):  
Amanda Lynch ◽  
David McGinnis ◽  
William L. Chapman ◽  
Jeffrey S. Tilley
Keyword(s):  
Regional Climate Model ◽  
Land Surface ◽  
Climate Model ◽  
Regional Climate ◽  
Climate System ◽  
System Model ◽  
Small Scale ◽  
Land Surface Models ◽  
Climate System Model ◽  
Surface Models

Different vegetation models impact the atmospheric response of a regional climate model in different ways, and hence have an impact upon the ability of that model to match an observed climatology. Using a multivariate principal-component analysis, we investigate the relationships between several land-surface models (BATS, LSM) coupled to a regional climate model, and observed climate parameters over the North Slope of Alaska. In this application, annual cycle simulations at 20 km spatial resolution are compared with European Centre for Medium-Range Weather Forecasts (ECMWF) climatology. Initial results demonstrate broad agreement between all models; however, small-scale regional variations between land-surface models indicate the strengths and weaknesses of the land-surface treatments in a climate system model. Specifically, we found that the greater surface-moisture availability and temperature-dependent albedo formulation of the LSM model allow for a higher proportion of low-level cloud, and a later, more rapid transition from the winter to the summer regime. Crucial to this transition is the seasonal cycle of incoming solar radiation. These preliminary results indicate the importance of the land-surface hydrologic cycle in modelling the seasonal transitions.

scholarly journals A regional atmosphere–ocean climate system model (CCLMv5.0clm7-NEMOv3.3-NEMOv3.6) over Europe including three marginal seas: on its stability and performance

2019 ◽  
Vol 12 (12) ◽  
pp. 5077-5095 ◽  
Author(s):  
Cristina Primo ◽  
Fanni D. Kelemen ◽  
Hendrik Feldmann ◽  
Naveed Akhtar ◽  
Bodo Ahrens
Keyword(s):  
20Th Century ◽  
Climate Models ◽  
Regional Climate ◽  
Climate Extremes ◽  
Coupled System ◽  
Climate System ◽  
Added Value ◽  
System Model ◽  
Climate System Model ◽  
Marginal Seas

Abstract. The frequency of extreme events has changed, having a direct impact on human lives. Regional climate models help us to predict these regional climate changes. This work presents an atmosphere–ocean coupled regional climate system model (RCSM; with the atmospheric component COSMO-CLM and the ocean component NEMO) over the European domain, including three marginal seas: the Mediterranean, North, and Baltic Sea. To test the model, we evaluate a simulation of more than 100 years (1900–2009) with a spatial grid resolution of about 25 km. The simulation was nested into a coupled global simulation with the model MPI-ESM in a low-resolution configuration, whose ocean temperature and salinity were nudged to the ocean–ice component of the MPI-ESM forced with the NOAA 20th Century Reanalysis (20CR). The evaluation shows the robustness of the RCSM and discusses the added value by the coupled marginal seas over an atmosphere-only simulation. The coupled system is stable for the complete 20th century and provides a better representation of extreme temperatures compared to the atmosphere-only model. The produced long-term dataset will help us to better understand the processes leading to meteorological and climate extremes.

scholarly journals A multivariate comparison of two land-surface models integrated into an Arctic Regional Climate System model

1997 ◽  
Vol 25 ◽  
pp. 127-131
Author(s):  
Amanda Lynch ◽  
David McGinnis ◽  
William L. Chapman ◽  
Jeffrey S. Tilley
Keyword(s):  
Regional Climate Model ◽  
Land Surface ◽  
Climate Model ◽  
Regional Climate ◽  
Climate System ◽  
System Model ◽  
Small Scale ◽  
Land Surface Models ◽  
Climate System Model ◽  
Surface Models

Different vegetation models impact the atmospheric response of a regional climate model in different ways, and hence have an impact upon the ability of that model to match an observed climatology. Using a multivariate principal-component analysis, we investigate the relationships between several land-surface models (BATS, LSM) coupled to a regional climate model, and observed climate parameters over the North Slope of Alaska. In this application, annual cycle simulations at 20 km spatial resolution are compared with European Centre for Medium-Range Weather Forecasts (ECMWF) climatology. Initial results demonstrate broad agreement between all models; however, small-scale regional variations between land-surface models indicate the strengths and weaknesses of the land-surface treatments in a climate system model. Specifically, we found that the greater surface-moisture availability and temperature-dependent albedo formulation of the LSM model allow for a higher proportion of low-level cloud, and a later, more rapid transition from the winter to the summer regime. Crucial to this transition is the seasonal cycle of incoming solar radiation. These preliminary results indicate the importance of the land-surface hydrologic cycle in modelling the seasonal transitions.

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