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A. Capotondi and W. R. Holland

thermohaline boundary conditions known as “mixed boundary conditions” (the surface ocean temperature is restored toward a prescribed temperature field, while the surface boundary condition for salinity is in the form of a prescribed freshwater flux). A steady state is often never reached, and the system evolution may undergo oscillatory phases in the intensity of the thermohaline circulation at a quasi-decadal period. Greatbatch and Zhang (1995) find a sustained oscillation with a period of 32 years in a

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Igor V. Kamenkovich and E. S. Sarachik

and freshwater fluxes nor the current skill of the numerical modeling of the ocean is sufficient for realistic simulations of the temperature and salinity. The ocean owes its stratification in large part to surface processes. Therefore, realistic simulation of sea surface temperature (SST) and sea surface salinity (SSS) is crucial for successful modeling of the ocean state, and a choice of surface boundary conditions is often dictated by the need to keep the values of simulated SST and SSS as

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Martin W. Jury, Andreas F. Prein, Heimo Truhetz, and Andreas Gobiet

2010 ). Thereby, the quality of the lateral boundary conditions (LBCs) from the GCM has a direct effect on the quality of the RCM simulation, which is often referred to as the “garbage in garbage out” problem ( Giorgi and Mearns 1991 ; Wang et al. 2004 ; Diaconescu et al. 2007 ). Frequently, GCM performance is analyzed by evaluating near-surface parameters within the RCM domain ( van Ulden and van Oldenborgh 2006 ; Maxino et al. 2008 ; Pierce et al. 2009 ; Errasti et al. 2011 ). However, since

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Geoffrey Gebbie and Peter Huybers

masses, there are issues that arise due to time variability. We do not expect for the surface boundary conditions, and thus the formation rate of water masses, to be constant in time. It is also unlikely that circulation pathways are steady in time. Evidence for changes in both temperature (e.g., Antonov et al. 2005 ; Gouretski and Koltermann 2007 ) and salinity (e.g., Wong et al. 1999 ; Bindoff and Mcdougall 2000 ; Dickson et al. 2003 ; Curry et al. 2003 ; Boyer et al. 2005 ; Curry and

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Joshua M. Boustead, Barbara E. Mayes, William Gargan, Jared L. Leighton, George Phillips, and Philip N. Schumacher

associated with significant tornadoes near discernible boundaries and in the warm sector to nontornadic boundary and warm sector supercells. Thunderstorms occur on the meso-Γ scale, and forcing for their development generally occurs on the meso- α scale. Nevertheless, synoptic-scale environments can produce favorable conditions for convective initiation, and those times when both the synoptic and mesoscale environments are favorable for tornadoes are generally when the largest outbreaks occur ( Doswell

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Daniel Argüeso, José Manuel Hidalgo-Muñoz, Sonia Raquel Gámiz-Fortis, María Jesús Esteban-Parra, and Yolanda Castro-Díez

climate model (RCM) enables the generation of high-resolution projections of climate change scenarios, and thus overcomes the resolution limitation of GCMs. The technique consists of finding an approximate solution to the equations of the atmosphere at high resolution over a confined region, using the GCMs to specify the boundary conditions. As a consequence, RCMs are able to resolve local-scale circulations that the GCMs cannot be expected to capture, providing added-value information with respect to

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M. Inoue, G. Matheou, and J. Teixeira

over the past decade by LES (e.g., Krueger et al. 1995 ; Wyant et al. 1997 ; Bretherton et al. 1999 ; Sandu and Stevens 2011 ; Chung et al. 2012 ). Past LES investigations of not only the Sc–Cu transition but ABL in general have been often limited to cases where horizontally periodic boundary conditions are applied. Although it is advantageous to retain the periodicity that enables numerically accurate implementations, it potentially poses limitations on the modeling of spatially developing

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Zhongshui Zou, Dongliang Zhao, Jun A. Zhang, Shuiqing Li, Yinhe Cheng, Haibin Lv, and Xin Ma

into this complex problem, most have focused on near-neutral conditions. To the best of our knowledge, only Nilsson et al. (2012) and Sullivan et al. (2014) have investigated the unstable boundary layer in the presence of swell. At low wind speeds, the buoyancy effect is another key factor that influences the ABL. Therefore, the focus of this study was to clarify the differences between the impact of swell on nonneutral and neutral ABLs. To address this issue, a constant flux model based on two

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David L. Williamson and Gerald L. Browning

inconjunction with the NCAR Global Circulation Model is described including deta/ls of the lateral boundary conditions. One set of experiments is described for which a 2- global simulation provides the correct orcontrol data against which 2- LAM forecasts are compared. Three cases are considered in which the LAMinflow boundary values are provided by the 2- global forecast, a 5* global forecast, or are held fixed equalto the initial values. Forecasts produced by the LAM with finer grids (up to [*) are also

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Chungu Lu and Gerald L. Browning

open boundaries in a limited-area model. Previous analyses of applications of the 4DVAR method to numerical weather forecasting have mostly been conducted for a set of ordinary differential equations (e.g., Daley 1991 ; Xu 1996 ; Lu and Browning 1998 ) or a set of partial differential equations with periodic boundary conditions (e.g., Lewis and Derber 1985 ; LeDimet and Talagrand 1986 ; Talagrand and Courtier 1987 ; Lu and Browning 2000 ). When one deals with 4DVAR data assimilations for a

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