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Günther Heinemann and Thomas Klein

the failure of the model to simulate these shallow clouds are weaknesses in the parameterization of cloud physics, but also too dry initial ECMWF moisture analyses. Although the movement of the MC over the open water is not captured by NORLAM, the successful simulation of the genesis stage of the MC over the ice slopes allows for an investigation of the forcing mechanisms. In order to examine the different contributions to the generation of cyclonic vorticity over the slopes, the vorticity budget

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Changhai Liu and Mitchell W. Moncrieff

and Roebber 2003 ; Done et al. 2004 ; Liu et al. 2006 ; Kain et al. 2006 ; Moncrieff and Liu 2006 ; Trier et al. 2006 ). Cloud microphysical processes play an important direct role in warm-season precipitating systems through direct influences on the cold pool strength (rainfall evaporation) and latent heating (condensation) as well as indirect influences on gravity waves and cloud–radiation interaction. Therefore, microphysical parameterizations could be a principal source of uncertainty in

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Zaviša I. Janjić

addition, the convective forcing, particularly the shallow one, could lead to negativeentropy changes. As the possible causes of the problems, the convection scheme, the processes at the air-water interface, andthe MY level 2 and level 2.5 PBL schemes were reexamined. A major revision of the BM scheme was made, anew marine viscous sublayer scheme was designed, and the MY schemes were retuned. The deep convective regimes are postulated to be characterized by a parameter called "cloud efficiency

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Richard J. Reed and Mark D. Albright

. The rapid intensification' is attributed to strong, deep baroclinic forcing in the presence of small effectivestatic stability. The latter term, as used here, denotes the existence of weak or neutral static stability in theprecipitating cloud mass combined with below normal dry static stability in the environment.1. Introduction On 13 November 1981 an extraordinary case of explosive cyclogenesis occurred in the eastern Pacific atlatitudes of 35--40-N. The central pressure of thestorm fell by

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Bradley F. Murphy

can be seen in Fig. 2a as the pressure maximum before the sudden fall in pressure. The approach of the cyclone brought about this sudden pressure drop and is also responsible for forcing the strong winds that occurred during this event. The warming that occurred before and during the event is also linked to the approach of the cyclone, as the system advects warm air ahead of it from the north to the Antarctic coast. Build up of cloud cover also occurs as the system approaches, as the infrared

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Y. Ruckstuhl and T. Janjić

parameter that addresses both sources of model error. We thereby hope to improve the simulation of convective clouds in the COSMO model, which we verify by comparing the resulting model forecasts to independent visible and near-infrared images of Meteorological Satellite (Meteosat) Spinning Enhanced Visible and Infrared Imager (SEVIRI) observations. In section 2 we introduce the COSMO model and explain the role of the roughness length in the context of the model equations. Then we discuss the

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Roger A. Pielke

layerparameterization scheme has been used to describe the initiation and evolution of sea-breeze convergencepatterns over south Florida as a function of the surface heat and momentum fluxes and of the large-scalesynoptic forcing. A minimum grid spacing of 11 km was used. Model results are presented for several differentinitial conditions and the results, when compared against cumulus cloud and shower patterns, demonstratethat the dry sea-breeze circulations are the dominant control on the locations of thunderstorm

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O. Coindreau, F. Hourdin, M. Haeffelin, A. Mathieu, and C. Rio

Energy and Water Cycle Experiment Cloud System Study. With this approach, it is possible to extract a number of diagnostics from the explicit simulations. It is also easier to identify which component of the parameterization is correct. The disadvantage here is that the explicit simulations are quite computationally demanding and the number of cases limited. A complementary approach consists of comparing continuous simulations of the local meteorology, relying for the large-scale forcing on the

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Ming Xue and William J. Martin

single arrows; the origin is at A1). This strong convergence forces a vertical updraft of nearly 4 m s −1 within the boundary layer, creating a local bump in the q υ contours and producing a cloud in the 3–5-km layer at 1956 ( Fig. 4a ). Such bumps act as obstacles to faster flows above, forcing internal gravity waves that are seen as the periodic patterns in the horizontal moisture convergence fields ( Fig. 4 ). While it is possible that these gravity waves, especially when they amplify, may

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David H. Bromwich, John J. Cassano, Thomas Klein, Gunther Heinemann, Keith M. Hines, Konrad Steffen, and Jason E. Box

examine three of the aircraft flights in more detail. 1) Flight KA3 Flight KA3 was selected for detailed analysis since it represents a case with moderate large-scale forcing for the katabatic wind. In addition, no cloud cover was observed over the ice sheet during the flight, and strong surface winds caused drifting snow near the surface. Figure 7 displays the modeled and observed profiles of potential temperature, wind speed, and wind direction for flight KA3. From the figure it is evident that the

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