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

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%.

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

Journal of Climate ◽

10.1175/2007jcli1730.1 ◽

2008 ◽

Vol 21 (1) ◽

pp. 114-133 ◽

Cited By ~ 27

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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Initial-value predictability of Antarctic sea ice in the Community Climate System Model 3

Geophysical Research Letters ◽

10.1002/grl.50410 ◽

2013 ◽

Vol 40 (10) ◽

pp. 2121-2124 ◽

Cited By ~ 47

Author(s):

Marika M. Holland ◽

Edward Blanchard-Wrigglesworth ◽

Jennifer Kay ◽

Steven Vavrus

Keyword(s):

Sea Ice ◽

Climate System ◽

System Model ◽

Initial Value ◽

Community Climate System Model ◽

Climate System Model ◽

Antarctic Sea Ice ◽

Community Climate

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Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100

Journal of Climate ◽

10.1175/jcli-d-11-00256.1 ◽

2012 ◽

Vol 25 (9) ◽

pp. 3071-3095 ◽

Cited By ~ 187

Author(s):

Peter J. Lawrence ◽

Johannes J. Feddema ◽

Gordon B. Bonan ◽

Gerald A. Meehl ◽

Brian C. O’Neill ◽

...

Keyword(s):

Land Cover ◽

Land Cover Change ◽

Climate Impacts ◽

Climate System ◽

System Model ◽

Community Climate System Model ◽

Climate System Model ◽

Model Version ◽

Wood Harvest ◽

Community Climate

To assess the climate impacts of historical and projected land cover change in the Community Climate System Model, version 4 (CCSM4), new time series of transient Community Land Model, version 4 (CLM4) plant functional type (PFT) and wood harvest parameters have been developed. The new parameters capture the dynamics of the Coupled Model Intercomparison Project phase 5 (CMIP5) land cover change and wood harvest trajectories for the historical period from 1850 to 2005 and for the four representative concentration pathway (RCP) scenarios from 2006 to 2100. Analysis of the biogeochemical impacts of land cover change in CCSM4 reveals that the model produced a historical cumulative land use flux of 127.7 PgC from 1850 to 2005, which is in general agreement with other global estimates of 156 PgC for the same period. The biogeophysical impacts of the transient land cover change parameters were cooling of the near-surface atmosphere over land by −0.1°C, through increased surface albedo and reduced shortwave radiation absorption. When combined with other transient climate forcings, the higher albedo from land cover change was counteracted by decreasing snow albedo from black carbon deposition and high-latitude warming. The future CCSM4 RCP simulations showed that the CLM4 transient PFT parameters can be used to represent a wide range of land cover change scenarios. In the reforestation scenario of RCP 4.5, CCSM4 simulated a drawdown of 67.3 PgC from the atmosphere into the terrestrial ecosystem and product pools. By contrast the RCP 8.5 scenario with deforestation and high wood harvest resulted in the release of 30.3 PgC currently stored in the ecosystem.

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