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Masahiro Watanabe, Fei-fei Jin, and Lin Pan

is reasonable to speculate that the convergence of the AIM solution will be slower (faster) for weaker (stronger) intrinsic diffusion of the dynamical operator. This is verified by evaluating ε in the T21 barotropic model used in Fig. 1 but with the e -folding decay time scale of the horizontal diffusion altered from 1 day to either half a day or 2 days. In both cases the AIM solution successfully converged with the best choice of γ , which varies from the original value. The resultant

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Liping Luo, Ming Xue, Kefeng Zhu, and Bowen Zhou

the three-moment Milbrandt and Yau (MY) scheme in a mesoscale NWP model. Comparisons with radar observations indicated that the typical supercell structures such as the hook echo, mesocyclone, and suspended overhang region were well reproduced, although the simulated maximum hail size on the ground was underpredicted. Snook et al. (2016) is a more recent example, which evaluated short-term ensemble forecasting of hail for a supercell storm over central Oklahoma using a two-moment MP scheme. They

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Tatsuya Seiki and Woosub Roh

-resolution GCMs because their computational cost is too expensive to perform evaluation experiments comprehensively. The ongoing CMIP6 is organizing an intercomparison of high-resolution GCMs, named HighResMIP ( Haarsma et al. 2016 ; Roberts et al. 2018 ). The GCM community expects cloud processes to be improved by increasing model resolutions up to 25 km, which is comparable to the one used in Morrison and Pinto (2005) . However, most GCMs in the HighResMIP still use conventional cloud microphysics with

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Grant J. Firl and David A. Randall

to compare the best-fit PDFs from one through four Gaussian clusters. The LES data are generated from the System for Atmospheric Modeling (SAM) ( Khairoutdinov and Randall 2003 ) using well-known test cases of a variety of cloud regimes, from shallow cumulus, to stratocumulus, to deep convection. The deep convection case is particularly interesting because of its “giga-LES” design. In all cases and for all numbers of Gaussian clusters, the PDFs are evaluated using their diagnosed statistical

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Xiping Zeng, Wei-Kuo Tao, Toshihisa Matsui, Shaocheng Xie, Stephen Lang, Minghua Zhang, David O’C Starr, and Xiaowen Li

observations over the past decades to test the model’s performance (e.g., Johnson et al. 2002 ; Tao et al. 2003 ; Lang et al. 2007 ; Zeng et al. 2008 , 2009b ). All of the numerical experiments in this study follow the model setup used in previous studies (e.g., Johnson et al. 2002 ; Xie et al. 2005 ; Xu et al. 2005 ; Blossey et al. 2007 ; Zeng et al. 2007 ), which simulated clouds with prescribed large-scale forcing derived from field observations. The experiments are 3D, using a 1-km horizontal

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M. Oltmanns, F. Straneo, H. Seo, and G. W. K. Moore

dynamical differences both between different resolution domains and between the smoothed and regular topography simulations. We will investigate these differences in the next section. b. Momentum balance To study the dynamical differences, we evaluate each term in the momentum balance for the downslope flow and investigate how it is affected by model resolution. To a good approximation, the atmospheric lapse rate is linear between 2500- and 6000-m heights. Below about 2000 m, the temperature gradient is

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B. B. Goswami, B. Khouider, R. Phani, P. Mukhopadhyay, and A. J. Majda

convection scheme as a control run. As an observational benchmark, we used outgoing longwave radiation (OLR) from NOAA (2.5° × 2.5°; daily; Liebmann and Smith 1996 ) and the thermodynamical and dynamical parameters from NCEP reanalysis (2.5° × 2.5°; daily; Kalnay et al. 1996 ) to evaluate the model-simulated climate using either SMCM or SAS. For both CFSsmcm and CFSv2 simulations, we used a horizontal resolution of T126, 64 vertical levels, and a time step of 10 min. We have extensively used the

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Melissa kazemirad and Mark A. Miller

Research and Forecasting (WRF) Model are used to produce a Lagrangian time series of the MBL cloud evolution in two postfrontal cases over periods of several tens of hours. Remote and in situ data from the ENA site are used to evaluate the results of these simulations. The goal of this study is to improve understanding of the decoupling process and its impact on MBL cloud morphology in summertime post-cold-frontal air masses traversing the eastern North Atlantic and beyond. Another goal is to determine

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Weiye Yao and Christiane Jablonowski

1. Introduction Modeling the quasi-biennial oscillation (QBO) in atmospheric general circulation models (GCMs) and understanding the QBO forcing mechanisms has been a challenge for decades. The QBO is a phenomenon in the equatorial stratosphere that occupies the region between 100 and 1 hPa. This region is characterized by a downward-propagating zonal wind regime that periodically changes from westerlies to easterlies. On average, the observed QBO period is 28 months, but it can vary

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Annelize van Niekerk, John F. Scinocca, and Theodore G. Shepherd

found from laboratory experiments ( Vosper 2000 ) and is used in other models. The sensitivity of its impact to the presence of low-level wave breaking is evaluated by switching the downslope drag enhancement on and off in the SM00 scheme. This leads to the set of six model configurations listed in Table 1 , which were executed at both 1×CO2 and 2×CO2. Taken together, the set of six SM00 configurations may additionally be viewed as systematically increasing the total low-level drag, and they

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