scholarly journals The low-resolution CCSM2 revisited: new adjustments and a present-day control run

2006 ◽  
Vol 3 (4) ◽  
pp. 1293-1348 ◽  
Author(s):  
M. Prange
Keyword(s):  
Meridional Overturning Circulation ◽  
Climate System ◽  
System Model ◽  
Climate Modelling ◽  
Low Resolution ◽  
Overturning Circulation ◽  
Community Climate System Model ◽  
Climate System Model ◽  
Meridional Overturning ◽  
Community Climate

Abstract. The low-resolution (T31) version of the Community Climate System Model CCSM2.0.1 is revisited and adjusted by deepening the Greenland-Scotland ridge, changing oceanic mixing parameters, and applying a regional freshwater flux adjustment at high northern latitudes. The main purpose of these adjustments is to maintain a robust Atlantic meridional overturning circulation which collapses in the original model release. The paper describes the present-day control run of the adjusted model which is brought into climatic equilibrium by applying a deep-ocean acceleration technique. The accelerated integration is extended by a 100-year synchronous phase. The simulated meridional overturning circulation has a maximum of 14×106 m3 s−1 in the North Atlantic. Most shortcomings found in the control run are identified as "typical problems" in global climate modelling. Given its good simulation skills and its relatively low resource demands, the adjusted low-resolution version of CCSM2.0.1 appears to be a reasonable alternative to the latest low-resolution Community Climate System Model release (CCSM3.0) if runtime is a critical factor.

scholarly journals The low-resolution CCSM2 revisited: new adjustments and a present-day control run

Ocean Science ◽  
2008 ◽  
Vol 4 (2) ◽  
pp. 151-181 ◽  
Author(s):  
M. Prange
Keyword(s):  
North Atlantic ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
System Model ◽  
Low Resolution ◽  
Overturning Circulation ◽  
Community Climate System Model ◽  
Climate System Model ◽  
Meridional Overturning ◽  
Community Climate

Abstract. The low-resolution (T31) version of the Community Climate System Model CCSM2.0.1 is revisited and adjusted by deepening the Greenland-Scotland ridge, changing oceanic mixing parameters, and applying a regional freshwater flux adjustment at high northern latitudes. The main purpose of these adjustments is to maintain a robust Atlantic meridional overturning circulation which collapses in the original model release. The paper describes the present-day control run of the adjusted model (referred to as "CCSM2/T31x3a") which is brought into climatic equilibrium by applying a deep-ocean acceleration technique. The accelerated integration is extended by a 100-year synchronous phase. The simulated meridional overturning circulation has a maximum of 14×106 m3 s−1 in the North Atlantic. The CCSM2/T31x3a control run is evaluated against observations and simulations with other climate models. Most shortcomings found in the CCSM2/T31x3a control run are identified as "typical problems" in global climate modelling. Finally, examples (simulation of North Atlantic hydrography, West African monsoon) are shown in which CCSM2/T31x3a has a better simulation skill than the latest low-resolution Community Climate System Model release, CCSM3/T31.

scholarly journals A Scalable and Adaptable Solution Framework within Components of the Community Climate System Model

2009 ◽  
pp. 332-341 ◽  
Author(s):  
Katherine J. Evans ◽  
Damian W. I. Rouson ◽  
Andrew G. Salinger ◽  
Mark A. Taylor ◽  
Wilbert Weijer ◽  
...  
Keyword(s):  
Climate System ◽  
System Model ◽  
Community Climate System Model ◽  
Climate System Model ◽  
Community Climate

scholarly journals Widely awaited community climate system model to be released soon

Eos ◽  
2002 ◽  
Vol 83 (11) ◽  
pp. 119
Author(s):  
Robert E. Dickinson ◽  
Jeffery Kiehl ◽  
Peter Gent
Keyword(s):  
Climate System ◽  
System Model ◽  
Community Climate System Model ◽  
Climate System Model ◽  
Community Climate

Sensitivity of Tropical Rainfall to Banda Sea Diffusivity in the Community Climate System Model

2008 ◽  
Vol 21 (23) ◽  
pp. 6445-6454 ◽  
Author(s):  
Markus Jochum ◽  
James Potemra
Keyword(s):  
General Circulation ◽  
Thick Layer ◽  
General Circulation Models ◽  
Climate System ◽  
System Model ◽  
Boreal Summer ◽  
Community Climate System Model ◽  
Climate System Model ◽  
Indonesian Seas ◽  
Community Climate

Abstract Several observational studies suggest that the vertical diffusivity in the Indonesian marginal seas is an order of magnitude larger than in the open ocean and what is used in most ocean general circulation models. The experiments described in this paper show that increasing the background diffusivity in the Banda Sea from the commonly used value of 0.1 cm2 s−1 to the observed value of 1 cm2 s−1 improves the watermass properties there by reproducing the observed thick layer of Banda Sea Water. The resulting reduced sea surface temperatures lead to weaker convection and a redistribution of precipitation, away from the Indonesian seas toward the equatorial Indian and Pacific Oceans. In particular, the boreal summer precipitation maximum of the Indonesian seas shifts northward from the Banda Sea toward Borneo, which reduces a longstanding bias in the simulation of the Austral–Asian Monsoon in the Community Climate System Model. Because of the positive feedback mechanisms inherent in tropical atmosphere dynamics, a reduction in Banda Sea heat loss of only 5% leads locally to a reduction in convection of 20%.

Origin of Pacific Multidecadal Variability in Community Climate System Model, Version 3 (CCSM3): A Combined Statistical and Dynamical Assessment

2008 ◽  
Vol 21 (1) ◽  
pp. 114-133 ◽  
Author(s):  
Yafang Zhong ◽  
Zhengyu Liu ◽  
R. Jacob
Keyword(s):  
North Pacific ◽  
Climate System ◽  
System Model ◽  
Community Climate System Model ◽  
Climate System Model ◽  
Multidecadal Variability ◽  
Model Version ◽  
The North ◽  
The North Pacific ◽  
Community Climate

Abstract Observations indicate that Pacific multidecadal variability (PMV) is a basinwide phenomenon with robust tropical–extratropical linkage, though its genesis remains the topic of much debate. In this study, the PMV in the Community Climate System Model, version 3 (CCSM3) is investigated with a combined statistical and dynamical approach. In agreement with observations, the modeled North Pacific climate system undergoes coherent multidecadal atmospheric and oceanic variability of a characteristic quasi-50-yr time scale, with apparent connections to the tropical Indo-Pacific. The statistical assessment based on the CCSM3 control integration cannot exclusively identify the origin of the modeled multidecadal linkage, while confirming the two-way interactions between the tropical and extratropical Pacific. Two sensitivity experiments are performed to further investigate the origin of the PMV. With the atmosphere decoupled from the tropical ocean, multidecadal variability in the North Pacific climate remains outstanding. In contrast, without midlatitude oceanic feedback to atmosphere, an experiment shows much reduced multidecadal power in both extratropical atmosphere and surface ocean; moreover, the tropical multidecadal variability seen in the CCSM3 control run virtually disappears. The combined statistical and dynamical assessment supports a midlatitude coupled origin for the PMV, which can be described as follows: extratropical large-scale air–sea interaction gives rise to multidecadal variability in the North Pacific region; this extratropical signal then imprints itself in the tropical Indo–Pacific climate system, through a robust tropical–extratropical teleconnection. This study highlights a midlatitude origin of multidecadal tropical–extratropical linkage in the Pacific in the CCSM3.

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