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Andrea Molod, Haydee Salmun, and Darryn W. Waugh

atmosphere, the planetary boundary layer (implicitly), the surface layer, and the viscous sublayer, all above the land or ocean surface. The vertical resolution is variable, and there are 8–10 layers inside the PBL, with the thinnest layers near the ground approximately 20–30 m thick. The turbulence parameterization consists of an element that handles the vertical diffusion above the surface layer using a second-order (or 1.5 order) closure scheme ( Helfand and Labraga 1988 ; Helfand et al. 1999 ), and

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Anning Cheng and Kuan-Man Xu

excessive amount of solar radiation reaching the ocean surface. In the past decade, there is an increasing trend to represent low-level clouds as a part of unified parameterizations of the planetary boundary layer (PBL) mixing and stratocumulus and shallow cumulus clouds. This approach is attractive because of the internal consistency on the treatments of the subgrid-scale processes. For example, the eddy diffusion mass flux (EDMF) approach ( Siebesma et al. 2007 ; Neggers et al. 2009 ), unifying the

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Frank O. Bryan, Robert Tomas, John M. Dennis, Dudley B. Chelton, Norman G. Loeb, and Julie L. McClean

Fig. 4 but for the winter season (Nov–Feb) in the Gulf Stream region. Fig . 6. Temporal correlation of high-pass filtered planetary albedo with SST. The correlations were computed using four years of monthly averaged data (48 months). Locations where ice appeared have been masked and stippling indicates statistical significance at the 95% level calculated using a two-sided t test. (a) 1.0° ocean and 0.5° atmosphere (expt 1); (b) 0.1° ocean and 0.5° atmosphere (expt 2); (c) 0.1° ocean and 0

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Kevin E. Trenberth and David P. Stepaniak

among components within the atmosphere. Of course, changes in planetary waves and storm tracks make an enormous difference to the climate locally, so this conclusion is not intended to diminish the vital role of atmospheric dynamics. But it does mean that there are important constraints, as noted by Stone (1978) , which helps provide some justification for simpler “energy balance” models of the climate system. Acknowledgments This research was sponsored by grants from the NOAA Office of Global

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Matthias Münnich, Mojib Latif, Stephan Venzke, and Ernst Maier-Reimer

evidence that the last phase shift from a warm to a cold North Pacific was caused by a change in tropical Pacific SST that introduced a change in the strength of the Aleutian low via established teleconnections. Furthermore, Trenberth and Hurrel (1994) also emphasize the role of the positive feedback mechanisms between the ocean and the atmosphere in the North Pacific itself. These feedback mechanisms were originally hypothesized by Namias (1959 , 1969) and Bjerknes (1964) : an anomalously warm

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Yun Qian, Huiping Yan, Larry K. Berg, Samson Hagos, Zhe Feng, Ben Yang, and Maoyi Huang

1. Introduction While numerical models resolve the large-scale flow, parameterizations are required for representing the effect of subgrid processes in the atmosphere such as radiation, convection, and turbulence that cannot be explicitly resolved by a numerical gridpoint model. While all physical parameterization packages play different roles in simulating the atmospheric processes, the turbulence parameterization is especially important for accurate representation of the planetary boundary

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Sun-Hee Shin and Kyung-Ja Ha

1. Introduction The height of the planetary boundary layer (PBL) is an important depth scale in atmospheric models for describing vertical mixing by turbulence and penetrating cumulus convection. Many large-scale numerical models use a vertical diffusion scheme to describe this turbulent mixing. Such vertical diffusion in unstable conditions depends strongly on the PBL height. The presence of large coherent structures, such as convective thermals, can produce turbulent transport from the

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Augustus F. Fanning and Andrew J. Weaver

of their mean and deviations from the mean, (7) becomes Here, μ " denotes a deviation from the time mean, μ ∗ denotes a deviation from the zonal mean, and μ ′ denotes a deviation from the vertical mean. The terms in (10) can be identified as the time variant (or eddy), barotropic gyre, baroclinic overturning, baroclinic gyre, and diffusive transport, respectively. The time-variant transport is obtained from We also define the time mean planetary (ocean plus atmosphere) heat transport ( T

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Doug M. Smith, Nick J. Dunstone, Adam A. Scaife, Emma K. Fiedler, Dan Copsey, and Steven C. Hardiman

; Petoukhov and Semenov 2010 ; Peings and Magnusdottir 2014 ; Sun et al. 2015 ; Pedersen et al. 2016 ). In contrast, the atmospheric response to Antarctic sea ice has received less attention ( Simmonds and Budd 1991 ; Simmonds and Wu 1993 ; Menéndez et al. 1999 ; Kidston et al. 2011 ; Bader et al. 2013 ). Recent studies have highlighted the importance of ocean–atmosphere coupling for simulating the response to sea ice ( Deser et al. 2015 , 2016 ; Tomas et al. 2016 ). However, the response to

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Michael Winton

-based model atmosphere overcompensated for the reduction in OHT across 40°S and 40°N so that the total energy transport into these regions was increased with decreasing ocean circulation. The low-latitude atmospheric heat transports were more responsive in the AM2 case. The models have similar responses of SST gradients, atmospheric stability, and relative humidity to ocean circulation strength, but their different physical formulations result in different low cloud, planetary albedo, and global

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