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Guy Plaut and Robert Vautard

periodic components of the atmospheric flow, the multichannel version of the singularspectrum analysis (M-SSA) is developed and applied to an NMC 32-year long set of 700-hPa geopotentialheights. In the same way that principal component analysis identifies the spatial patterns dominating the variability,M-SSA identifies dynamically relevant space-time patterns and provides an adaptive filtering technique.Three major low-frequency oscillations (LFOs) are found, with periods of 70 days, 40-45 days, and 30

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Michael C. Morgan

well forecast by a number of operational models including the NOGAPS model. Errors in the NOGAPS forecast of surface pressure were as large as 18 hPa (refer to Fig. 1c of Langland et al. 1999 ). Knowledge of the three-dimensional forecast error allows for an optimal modification of the initial analysis to be constructed using the pseudoinverse technique described by Gelaro et al. (1998) . The modification is optimal in the sense that its addition to the initial (control) analysis yields a 42-h

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Wojciech W. Grabowski, Xiaoqing Wu, and Mitchell W. Moncrieff

framework is established for the way in which cloud-resolving numerical models are used to investigate the role of precipitating cloud systems in climate and weather forecasting models. Emphasis is on modelswith periodic lateral boundary conditions that eliminate unrealistic numerically generated circulations caused byopen boundary conditions in long-term simulations. Defined in this formalism is the concept of large-scalefoming and the cloud-environment interactions that are consistent with the

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Y. Martinez, G. Brunet, and M. K. Yau

of hurricanes. A better knowledge of the dynamics of hurricane asymmetries is vital to understand inner-core dynamics and ultimately improve hurricane intensity forecasting systems. However, many aspects related with the origin, propagation, space–time structure, and dynamics of the hurricane asymmetries still remain unsolved. The goal of this series of papers is therefore to better understand the kinematics and dynamics of hurricane asymmetries, particularly in the hurricane intensity changes

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Takanobu Yamaguchi, W. Alan Brewer, and Graham Feingold

approximately 1 km. Thus, while choice of resolution is unarguably important, the scales of mesoscale organization suggest that the choice of domain size may be of equal importance. We will test the sensitivity of the simulated turbulence to domain size for the Advanced Research Weather Research and Forecasting Model (ARW) and compare ARW trends to those in the evaluation of modeled turbulence by DDJ04 . Although the community ARW model was not necessarily developed with LES application in mind, it has

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William J. Moroz

. One cell of a symmetric lake breeze has been modelled numerically using the techniques developed byEstoque for the sea breeze with appropriate boundary condition modifications to account for the finiteextent of the water surface. The temperature wave over the land was specified in accordance with observedtemperatures on days when a lake breeze did occur. Results of the numerical forecast after 6 hr and after9 hr of meteorological time are compared with the observed lake breeze at corresponding

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Heini Wernli and Michael Sprenger

identify tilted PV streamers and does not distinguish between streamers and cutoffs. The latter method is computationally expensive and focuses on very thin filaments that are typically not resolved by operational (re)analysis datasets. In this study, an alternative approach will be introduced and applied to the 15-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-15) in the Northern Hemisphere. The method is based mainly upon a contour identification algorithm and can

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King-Sheng Tai and Yoshi Ogura

III-b data provided by the European Centre for Medium-Range Weather Forecasts and theoutgoing longwave radiation data measured by satellites are used to investigate observationally relationshipsbetween deep cloud activity and large-scale meteorological fields during the Northern Hemisphere summer(May-September) of 1979 over the eastern Pacific. Aside from the summer monsoon area over southern andeastern Asia, the eastern Pacific is the area where strong, deep-convection frequently develops in the

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Y. Martinez, G. Brunet, and M. K. Yau

Willoughby et al. (1982) , Willoughby (1990c , a , b ), Black and Willoughby (1992) , and Kossin and Sitkowski (2009) . With the introduction of passive microwave techniques, observations of concentric eyewalls and ERC became more frequent. Hawkins et al. (2006) estimated that about 70% of all the major hurricanes in the Atlantic Ocean have undergone ERC. A better knowledge of concentric eyewall and ERC is vital to understand inner-core dynamics, short-term intensity trends, and upgrading of

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Terence J. O’Kane, James S. Risbey, Christian Franzke, Illia Horenko, and Didier P. Monselesan

analyses and forecasts from the European Centre for Medium-Range Weather Forecasting (ECMWF) operational archives. They found only one preferred region for blocking in the SH, around 180° longitude, corresponding to the Australian blocking region and that blocking in the SH was considerably more difficult to characterize than in the Northern Hemisphere (NH). Pook and Gibson (1999) comprehensively review the development of blocking indices specific to the SH as used in operational weather prediction

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